Use static import of Assert in tests (#10126)

Also removes dependency on junit.framework.TestCase .

170 files changed, 2211 insertions, 2046 deletions

diff --git a/server/src/test/java/com/vaadin/data/BeanBinderTest.java b/server/src/test/java/com/vaadin/data/BeanBinderTest.java
index 35722405f7..45610754d5 100644
--- a/server/src/test/java/com/vaadin/data/BeanBinderTest.java
+++ b/server/src/test/java/com/vaadin/data/BeanBinderTest.java
@@ -1,7 +1,9 @@
 package com.vaadin.data;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
 
 import java.io.Serializable;
 import java.time.LocalDate;
@@ -14,7 +16,6 @@ import javax.validation.constraints.NotNull;
 import javax.validation.constraints.Size;
 
 import org.hibernate.validator.constraints.NotEmpty;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -410,7 +411,7 @@ public class BeanBinderTest
         binder.bind(field, "firstname");
         binder.setBean(bean);
 
-        Assert.assertTrue(field.isRequiredIndicatorVisible());
+        assertTrue(field.isRequiredIndicatorVisible());
         testSerialization(binder);
     }
 
@@ -424,7 +425,7 @@ public class BeanBinderTest
         binder.bind(field, "age");
         binder.setBean(bean);
 
-        Assert.assertTrue(field.isRequiredIndicatorVisible());
+        assertTrue(field.isRequiredIndicatorVisible());
         testSerialization(binder);
     }
 
@@ -438,7 +439,7 @@ public class BeanBinderTest
         binder.bind(field, "lastname");
         binder.setBean(bean);
 
-        Assert.assertTrue(field.isRequiredIndicatorVisible());
+        assertTrue(field.isRequiredIndicatorVisible());
         testSerialization(binder);
     }
 
@@ -453,7 +454,7 @@ public class BeanBinderTest
         binder.bind(field, "subfield.name");
         binder.setBean(bean);
 
-        Assert.assertTrue(field.isRequiredIndicatorVisible());
+        assertTrue(field.isRequiredIndicatorVisible());
         testSerialization(binder);
     }
 
@@ -470,7 +471,7 @@ public class BeanBinderTest
         binder.bind(field, "subfield.subsub.value");
         binder.setBean(bean);
 
-        Assert.assertTrue(field.isRequiredIndicatorVisible());
+        assertTrue(field.isRequiredIndicatorVisible());
         testSerialization(binder);
     }
 
@@ -484,9 +485,9 @@ public class BeanBinderTest
         RequiredConstraints bean = new RequiredConstraints();
         bean.setSubfield(new SubConstraint());
         binder.setBean(bean);
-        Assert.assertFalse(binder.validate().isOk());
+        assertFalse(binder.validate().isOk());
         field.setValue("overfive");
-        Assert.assertTrue(binder.validate().isOk());
+        assertTrue(binder.validate().isOk());
     }
 
     @Test
@@ -502,9 +503,9 @@ public class BeanBinderTest
         subfield.setSubsub(new SubSubConstraint());
         binder.setBean(bean);
 
-        Assert.assertFalse(binder.validate().isOk());
+        assertFalse(binder.validate().isOk());
         field.setValue("overtencharacters");
-        Assert.assertTrue(binder.validate().isOk());
+        assertTrue(binder.validate().isOk());
     }
 
     private void assertInvalid(HasValue<?> field, String message) {
diff --git a/server/src/test/java/com/vaadin/data/BeanPropertySetTest.java b/server/src/test/java/com/vaadin/data/BeanPropertySetTest.java
index c577db6067..7b492ad012 100644
--- a/server/src/test/java/com/vaadin/data/BeanPropertySetTest.java
+++ b/server/src/test/java/com/vaadin/data/BeanPropertySetTest.java
@@ -15,6 +15,10 @@
  */
 package com.vaadin.data;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotSame;
+import static org.junit.Assert.assertSame;
+
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.ObjectInputStream;
@@ -26,7 +30,6 @@ import java.util.Map;
 import java.util.Set;
 import java.util.stream.Collectors;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.data.provider.bov.Person;
@@ -45,8 +48,7 @@ public class BeanPropertySetTest {
         PropertySet<Person> deserializedPropertySet = ClassesSerializableTest
                 .serializeAndDeserialize(originalPropertySet);
 
-        Assert.assertSame(
-                "Deserialized instance should be the same as the original",
+        assertSame("Deserialized instance should be the same as the original",
                 originalPropertySet, deserializedPropertySet);
     }
 
@@ -74,10 +76,9 @@ public class BeanPropertySetTest {
         PropertySet<Person> deserializedPropertySet = (PropertySet<Person>) in
                 .readObject();
 
-        Assert.assertSame(
-                "Deserialized instance should be the same as in the cache",
+        assertSame("Deserialized instance should be the same as in the cache",
                 BeanPropertySet.get(Person.class), deserializedPropertySet);
-        Assert.assertNotSame(
+        assertNotSame(
                 "Deserialized instance should not be the same as the original",
                 originalPropertySet, deserializedPropertySet);
     }
@@ -95,11 +96,10 @@ public class BeanPropertySetTest {
         Person person = new Person("Milennial", 2000);
         Integer age = (Integer) getter.apply(person);
 
-        Assert.assertEquals("Deserialized definition should be functional",
+        assertEquals("Deserialized definition should be functional",
                 Integer.valueOf(2000), age);
 
-        Assert.assertSame(
-                "Deserialized instance should be the same as in the cache",
+        assertSame("Deserialized instance should be the same as in the cache",
                 BeanPropertySet.get(Person.class).getProperty("born")
                         .orElseThrow(RuntimeException::new),
                 deserializedDefinition);
@@ -125,11 +125,10 @@ public class BeanPropertySetTest {
 
         Integer postalCode = (Integer) getter.apply(person);
 
-        Assert.assertEquals("Deserialized definition should be functional",
+        assertEquals("Deserialized definition should be functional",
                 address.getPostalCode(), postalCode);
 
-        Assert.assertSame(
-                "Deserialized instance should be the same as in the cache",
+        assertSame("Deserialized instance should be the same as in the cache",
                 BeanPropertySet.get(com.vaadin.tests.data.bean.Person.class)
                         .getProperty("address.postalCode").orElseThrow(
                                 RuntimeException::new),
@@ -153,7 +152,7 @@ public class BeanPropertySetTest {
 
         String firstName = (String) getter.apply(son);
 
-        Assert.assertEquals(grandFather.getFirstName(), firstName);
+        assertEquals(grandFather.getFirstName(), firstName);
     }
 
     @Test(expected = NullPointerException.class)
@@ -188,7 +187,7 @@ public class BeanPropertySetTest {
         Set<String> propertyNames = propertySet.getProperties()
                 .map(PropertyDefinition::getName).collect(Collectors.toSet());
 
-        Assert.assertEquals(new HashSet<>(Arrays.asList("name", "born")),
+        assertEquals(new HashSet<>(Arrays.asList("name", "born")),
                 propertyNames);
     }
 }
diff --git a/server/src/test/java/com/vaadin/data/BinderBookOfVaadinTest.java b/server/src/test/java/com/vaadin/data/BinderBookOfVaadinTest.java
index 89987d5f62..2d7c6631b0 100644
--- a/server/src/test/java/com/vaadin/data/BinderBookOfVaadinTest.java
+++ b/server/src/test/java/com/vaadin/data/BinderBookOfVaadinTest.java
@@ -15,6 +15,12 @@
  */
 package com.vaadin.data;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+
 import java.time.LocalDate;
 import java.util.List;
 import java.util.Locale;
@@ -22,7 +28,6 @@ import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.stream.Collectors;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -186,16 +191,16 @@ public class BinderBookOfVaadinTest {
 
         field.setValue("not-email");
         BinderValidationStatus<?> status = binder.validate();
-        Assert.assertEquals(1, status.getFieldValidationErrors().size());
-        Assert.assertEquals("This doesn't look like a valid email address",
+        assertEquals(1, status.getFieldValidationErrors().size());
+        assertEquals("This doesn't look like a valid email address",
                 status.getFieldValidationErrors().get(0).getMessage().get());
-        Assert.assertEquals("This doesn't look like a valid email address",
+        assertEquals("This doesn't look like a valid email address",
                 ((AbstractErrorMessage) field.getErrorMessage()).getMessage());
 
         field.setValue("abc@vaadin.com");
         status = binder.validate();
-        Assert.assertEquals(0, status.getBeanValidationErrors().size());
-        Assert.assertNull(field.getErrorMessage());
+        assertEquals(0, status.getBeanValidationErrors().size());
+        assertNull(field.getErrorMessage());
     }
 
     @Test
@@ -208,16 +213,16 @@ public class BinderBookOfVaadinTest {
 
         field.setValue("a");
         BinderValidationStatus<?> status = binder.validate();
-        Assert.assertEquals(1, status.getFieldValidationErrors().size());
-        Assert.assertEquals("Last name must contain at least three characters",
+        assertEquals(1, status.getFieldValidationErrors().size());
+        assertEquals("Last name must contain at least three characters",
                 status.getFieldValidationErrors().get(0).getMessage().get());
-        Assert.assertEquals("Last name must contain at least three characters",
+        assertEquals("Last name must contain at least three characters",
                 ((AbstractErrorMessage) field.getErrorMessage()).getMessage());
 
         field.setValue("long last name");
         status = binder.validate();
-        Assert.assertEquals(0, status.getFieldValidationErrors().size());
-        Assert.assertNull(field.getErrorMessage());
+        assertEquals(0, status.getFieldValidationErrors().size());
+        assertNull(field.getErrorMessage());
     }
 
     @Test
@@ -233,24 +238,24 @@ public class BinderBookOfVaadinTest {
         field.setValue("not-email");
         BinderValidationStatus<?> status = binder.validate();
         // Only one error per field should be reported
-        Assert.assertEquals(1, status.getFieldValidationErrors().size());
-        Assert.assertEquals("This doesn't look like a valid email address",
+        assertEquals(1, status.getFieldValidationErrors().size());
+        assertEquals("This doesn't look like a valid email address",
                 status.getFieldValidationErrors().get(0).getMessage().get());
-        Assert.assertEquals("This doesn't look like a valid email address",
+        assertEquals("This doesn't look like a valid email address",
                 ((AbstractErrorMessage) field.getErrorMessage()).getMessage());
 
         field.setValue("abc@vaadin.com");
         status = binder.validate();
-        Assert.assertEquals(1, status.getFieldValidationErrors().size());
-        Assert.assertEquals("Only acme.com email addresses are allowed",
+        assertEquals(1, status.getFieldValidationErrors().size());
+        assertEquals("Only acme.com email addresses are allowed",
                 status.getFieldValidationErrors().get(0).getMessage().get());
-        Assert.assertEquals("Only acme.com email addresses are allowed",
+        assertEquals("Only acme.com email addresses are allowed",
                 ((AbstractErrorMessage) field.getErrorMessage()).getMessage());
 
         field.setValue("abc@acme.com");
         status = binder.validate();
-        Assert.assertEquals(0, status.getFieldValidationErrors().size());
-        Assert.assertNull(field.getErrorMessage());
+        assertEquals(0, status.getFieldValidationErrors().size());
+        assertNull(field.getErrorMessage());
     }
 
     @Test
@@ -276,20 +281,20 @@ public class BinderBookOfVaadinTest {
         // Test that the book code works
         BookPerson bookPerson = new BookPerson(1972, 4);
         binder.setBean(bookPerson);
-        Assert.assertEquals(4.0, salaryLevelField.getValue().doubleValue(), 0);
-        Assert.assertEquals("1,972", yearOfBirthField.getValue());
+        assertEquals(4.0, salaryLevelField.getValue().doubleValue(), 0);
+        assertEquals("1,972", yearOfBirthField.getValue());
 
         bookPerson.setSalaryLevel(8);
         binder.readBean(bookPerson);
-        Assert.assertEquals(8.0, salaryLevelField.getValue().doubleValue(), 0);
+        assertEquals(8.0, salaryLevelField.getValue().doubleValue(), 0);
         bookPerson.setYearOfBirth(123);
         binder.readBean(bookPerson);
-        Assert.assertEquals("123", yearOfBirthField.getValue());
+        assertEquals("123", yearOfBirthField.getValue());
 
         yearOfBirthField.setValue("2016");
         salaryLevelField.setValue(1.0);
-        Assert.assertEquals(2016, bookPerson.getYearOfBirth());
-        Assert.assertEquals(1, bookPerson.getSalaryLevel());
+        assertEquals(2016, bookPerson.getYearOfBirth());
+        assertEquals(1, bookPerson.getSalaryLevel());
     }
 
     @Test
@@ -306,7 +311,7 @@ public class BinderBookOfVaadinTest {
         binder.setBean(new BookPerson(1900, 5));
         yearOfBirthField.setValue("abc");
         binder.validate();
-        Assert.assertEquals("Please&#32;enter&#32;a&#32;number",
+        assertEquals("Please&#32;enter&#32;a&#32;number",
                 yearOfBirthField.getComponentError().getFormattedHtmlMessage());
     }
 
@@ -333,33 +338,33 @@ public class BinderBookOfVaadinTest {
         returning.setValue(after);
 
         BinderValidationStatus<Trip> status = binder.validate();
-        Assert.assertTrue(status.getBeanValidationErrors().isEmpty());
-        Assert.assertNull(departing.getComponentError());
-        Assert.assertNull(returning.getComponentError());
+        assertTrue(status.getBeanValidationErrors().isEmpty());
+        assertNull(departing.getComponentError());
+        assertNull(returning.getComponentError());
 
         // update returning => validation is done against this field
         returning.setValue(past);
         status = binder.validate();
 
-        Assert.assertFalse(status.getFieldValidationErrors().isEmpty());
-        Assert.assertNotNull(returning.getComponentError());
-        Assert.assertNull(departing.getComponentError());
+        assertFalse(status.getFieldValidationErrors().isEmpty());
+        assertNotNull(returning.getComponentError());
+        assertNull(departing.getComponentError());
 
         // set correct value back
         returning.setValue(before);
         status = binder.validate();
 
-        Assert.assertTrue(status.getFieldValidationErrors().isEmpty());
-        Assert.assertNull(departing.getComponentError());
-        Assert.assertNull(returning.getComponentError());
+        assertTrue(status.getFieldValidationErrors().isEmpty());
+        assertNull(departing.getComponentError());
+        assertNull(returning.getComponentError());
 
         // update departing => validation is done because of listener added
         departing.setValue(after);
         status = binder.validate();
 
-        Assert.assertFalse(status.getFieldValidationErrors().isEmpty());
-        Assert.assertNotNull(returning.getComponentError());
-        Assert.assertNull(departing.getComponentError());
+        assertFalse(status.getFieldValidationErrors().isEmpty());
+        assertNotNull(returning.getComponentError());
+        assertNull(departing.getComponentError());
 
     }
 
@@ -386,29 +391,29 @@ public class BinderBookOfVaadinTest {
         returning.setValue(after);
 
         BindingValidationStatus<LocalDate> result = returnBinding.validate();
-        Assert.assertFalse(result.isError());
-        Assert.assertNull(departing.getComponentError());
+        assertFalse(result.isError());
+        assertNull(departing.getComponentError());
 
         // update returning => validation is done against this field
         returning.setValue(past);
         result = returnBinding.validate();
 
-        Assert.assertTrue(result.isError());
-        Assert.assertNotNull(returning.getComponentError());
+        assertTrue(result.isError());
+        assertNotNull(returning.getComponentError());
 
         // set correct value back
         returning.setValue(before);
         result = returnBinding.validate();
 
-        Assert.assertFalse(result.isError());
-        Assert.assertNull(departing.getComponentError());
+        assertFalse(result.isError());
+        assertNull(departing.getComponentError());
 
         // update departing => validation is done because of listener added
         departing.setValue(after);
         result = returnBinding.validate();
 
-        Assert.assertTrue(result.isError());
-        Assert.assertNotNull(returning.getComponentError());
+        assertTrue(result.isError());
+        assertNotNull(returning.getComponentError());
     }
 
     @Test
@@ -423,14 +428,14 @@ public class BinderBookOfVaadinTest {
         field.setValue("foo");
         binder.validate();
 
-        Assert.assertTrue(emailStatus.isVisible());
-        Assert.assertEquals(msg, emailStatus.getValue());
+        assertTrue(emailStatus.isVisible());
+        assertEquals(msg, emailStatus.getValue());
 
         field.setValue("foo@vaadin.com");
         binder.validate();
 
-        Assert.assertFalse(emailStatus.isVisible());
-        Assert.assertEquals("", emailStatus.getValue());
+        assertFalse(emailStatus.isVisible());
+        assertEquals("", emailStatus.getValue());
     }
 
     @Test
@@ -451,24 +456,24 @@ public class BinderBookOfVaadinTest {
         field.setValue("aa");
         binder.validate();
 
-        Assert.assertTrue(nameStatus.isVisible());
-        Assert.assertEquals(msg, nameStatus.getValue());
-        Assert.assertNotNull(statusCapture.get());
+        assertTrue(nameStatus.isVisible());
+        assertEquals(msg, nameStatus.getValue());
+        assertNotNull(statusCapture.get());
         BindingValidationStatus<?> status = statusCapture.get();
-        Assert.assertEquals(Status.ERROR, status.getStatus());
-        Assert.assertEquals(msg, status.getMessage().get());
-        Assert.assertEquals(field, status.getField());
+        assertEquals(Status.ERROR, status.getStatus());
+        assertEquals(msg, status.getMessage().get());
+        assertEquals(field, status.getField());
 
         field.setValue("foo");
         binder.validate();
 
-        Assert.assertFalse(nameStatus.isVisible());
-        Assert.assertEquals("", nameStatus.getValue());
-        Assert.assertNotNull(statusCapture.get());
+        assertFalse(nameStatus.isVisible());
+        assertEquals("", nameStatus.getValue());
+        assertNotNull(statusCapture.get());
         status = statusCapture.get();
-        Assert.assertEquals(Status.OK, status.getStatus());
-        Assert.assertFalse(status.getMessage().isPresent());
-        Assert.assertEquals(field, status.getField());
+        assertEquals(Status.OK, status.getStatus());
+        assertFalse(status.getMessage().isPresent());
+        assertEquals(field, status.getField());
     }
 
     @Test
@@ -501,14 +506,14 @@ public class BinderBookOfVaadinTest {
         });
 
         emailField.setValue("foo@bar.com");
-        Assert.assertTrue(binder.writeBeanIfValid(person));
+        assertTrue(binder.writeBeanIfValid(person));
         // Person updated
-        Assert.assertEquals("foo@bar.com", person.getEmail());
+        assertEquals("foo@bar.com", person.getEmail());
 
         emailField.setValue("");
-        Assert.assertFalse(binder.writeBeanIfValid(person));
+        assertFalse(binder.writeBeanIfValid(person));
         // Person updated because phone and email are both empty
-        Assert.assertEquals("foo@bar.com", person.getEmail());
+        assertEquals("foo@bar.com", person.getEmail());
     }
 
     @Test
@@ -527,21 +532,21 @@ public class BinderBookOfVaadinTest {
                 .bind(BookPerson::getYearOfBirth, BookPerson::setYearOfBirth);
 
         yearOfBirthField.setValue("abc");
-        Assert.assertEquals("Doesn't look like a year", binder.validate()
+        assertEquals("Doesn't look like a year", binder.validate()
                 .getFieldValidationErrors().get(0).getMessage().get());
         yearOfBirthField.setValue("abcd");
-        Assert.assertEquals("Must enter a number", binder.validate()
+        assertEquals("Must enter a number", binder.validate()
                 .getFieldValidationErrors().get(0).getMessage().get());
         yearOfBirthField.setValue("1200");
-        Assert.assertEquals("Person must be born in the 20th century",
+        assertEquals("Person must be born in the 20th century",
                 binder.validate().getFieldValidationErrors().get(0).getMessage()
                         .get());
 
         yearOfBirthField.setValue("1950");
-        Assert.assertFalse(binder.validate().hasErrors());
+        assertFalse(binder.validate().hasErrors());
         BookPerson person = new BookPerson(1500, 12);
         binder.writeBean(person);
-        Assert.assertEquals(1950, person.getYearOfBirth());
+        assertEquals(1950, person.getYearOfBirth());
     }
 
     class MyConverter implements Converter<String, Integer> {
@@ -580,17 +585,17 @@ public class BinderBookOfVaadinTest {
         binder.setBean(p);
 
         yearOfBirthField.setValue("abc");
-        Assert.assertTrue(binder.validate().hasErrors());
-        Assert.assertEquals("Please enter a number", binder.validate()
+        assertTrue(binder.validate().hasErrors());
+        assertEquals("Please enter a number", binder.validate()
                 .getFieldValidationErrors().get(0).getMessage().get());
 
         yearOfBirthField.setValue("123");
-        Assert.assertTrue(binder.validate().isOk());
+        assertTrue(binder.validate().isOk());
 
         p.setYearOfBirth(12500);
         binder.readBean(p);
-        Assert.assertEquals("12500", yearOfBirthField.getValue());
-        Assert.assertTrue(binder.validate().isOk());
+        assertEquals("12500", yearOfBirthField.getValue());
+        assertTrue(binder.validate().isOk());
     }
 
     @Test
@@ -617,31 +622,31 @@ public class BinderBookOfVaadinTest {
         yearOfBirth.setValue("2001");
 
         BinderValidationStatus<?> status = binder.validate();
-        Assert.assertEquals(0, status.getFieldValidationErrors().size());
-        Assert.assertEquals(1, status.getBeanValidationErrors().size());
-        Assert.assertEquals(message,
+        assertEquals(0, status.getFieldValidationErrors().size());
+        assertEquals(1, status.getBeanValidationErrors().size());
+        assertEquals(message,
                 status.getBeanValidationErrors().get(0).getErrorMessage());
 
-        Assert.assertEquals(message, formStatusLabel.getValue());
+        assertEquals(message, formStatusLabel.getValue());
 
         // value is correct, status label is cleared
         yearOfBirth.setValue("1999");
 
         status = binder.validate();
-        Assert.assertFalse(status.hasErrors());
+        assertFalse(status.hasErrors());
 
-        Assert.assertEquals("", formStatusLabel.getValue());
+        assertEquals("", formStatusLabel.getValue());
 
         // both bean validators fail, should be two error messages chained
         yearOfBirth.setValue("2000");
 
         status = binder.validate();
-        Assert.assertEquals(2, status.getBeanValidationResults().size());
-        Assert.assertEquals(0, status.getFieldValidationErrors().size());
-        Assert.assertEquals(2, status.getBeanValidationErrors().size());
+        assertEquals(2, status.getBeanValidationResults().size());
+        assertEquals(0, status.getFieldValidationErrors().size());
+        assertEquals(2, status.getBeanValidationErrors().size());
 
         // only first error is shown
-        Assert.assertEquals(message, formStatusLabel.getValue());
+        assertEquals(message, formStatusLabel.getValue());
     }
 
     @Test
@@ -682,43 +687,42 @@ public class BinderBookOfVaadinTest {
         // first binding validation fails, no bean level validation is done
         yearOfBirth.setValue("2001");
         BinderValidationStatus<?> status = binder.validate();
-        Assert.assertEquals(1, status.getFieldValidationErrors().size());
-        Assert.assertEquals(bindingMessage,
+        assertEquals(1, status.getFieldValidationErrors().size());
+        assertEquals(bindingMessage,
                 status.getFieldValidationErrors().get(0).getMessage().get());
 
-        Assert.assertEquals("", formStatusLabel.getValue());
+        assertEquals("", formStatusLabel.getValue());
 
         // first bean validator fails and passes error message to status label
         yearOfBirth.setValue("2002");
 
         status = binder.validate();
-        Assert.assertEquals(0, status.getFieldValidationErrors().size());
-        Assert.assertEquals(1, status.getBeanValidationErrors().size());
-        Assert.assertEquals(message,
+        assertEquals(0, status.getFieldValidationErrors().size());
+        assertEquals(1, status.getBeanValidationErrors().size());
+        assertEquals(message,
                 status.getBeanValidationErrors().get(0).getErrorMessage());
 
-        Assert.assertEquals(message, formStatusLabel.getValue());
+        assertEquals(message, formStatusLabel.getValue());
 
         // value is correct, status label is cleared
         yearOfBirth.setValue("1998");
 
         status = binder.validate();
-        Assert.assertTrue(status.isOk());
-        Assert.assertFalse(status.hasErrors());
-        Assert.assertEquals(0, status.getFieldValidationErrors().size());
-        Assert.assertEquals(0, status.getBeanValidationErrors().size());
+        assertTrue(status.isOk());
+        assertFalse(status.hasErrors());
+        assertEquals(0, status.getFieldValidationErrors().size());
+        assertEquals(0, status.getBeanValidationErrors().size());
 
-        Assert.assertEquals("", formStatusLabel.getValue());
+        assertEquals("", formStatusLabel.getValue());
 
         // both bean validators fail, should be two error messages chained
         yearOfBirth.setValue("2000");
 
         status = binder.validate();
-        Assert.assertEquals(0, status.getFieldValidationErrors().size());
-        Assert.assertEquals(2, status.getBeanValidationErrors().size());
+        assertEquals(0, status.getFieldValidationErrors().size());
+        assertEquals(2, status.getBeanValidationErrors().size());
 
-        Assert.assertEquals(message + "\n" + message2,
-                formStatusLabel.getValue());
+        assertEquals(message + "\n" + message2, formStatusLabel.getValue());
 
     }
 
@@ -741,43 +745,43 @@ public class BinderBookOfVaadinTest {
                 .withValidator(new StringLengthValidator("", 1, 3))
                 .bind(BookPerson::getLastName, BookPerson::setLastName);
         // no changes
-        Assert.assertFalse(saveButton.isEnabled());
-        Assert.assertFalse(resetButton.isEnabled());
+        assertFalse(saveButton.isEnabled());
+        assertFalse(resetButton.isEnabled());
         verifyEventIsFired(eventIsFired);
 
         BookPerson person = new BookPerson(2000, 1);
         binder.readBean(person);
         // no changes
-        Assert.assertFalse(saveButton.isEnabled());
-        Assert.assertFalse(resetButton.isEnabled());
+        assertFalse(saveButton.isEnabled());
+        assertFalse(resetButton.isEnabled());
         verifyEventIsFired(eventIsFired);
 
         field.setValue("a");
         // binder is not bound, no event fired
         // no changes: see #375. There should be a change and enabled state
-        Assert.assertTrue(saveButton.isEnabled());
-        Assert.assertTrue(resetButton.isEnabled());
-        Assert.assertTrue(eventIsFired.get());
+        assertTrue(saveButton.isEnabled());
+        assertTrue(resetButton.isEnabled());
+        assertTrue(eventIsFired.get());
 
         binder.writeBeanIfValid(person);
         // no changes
-        Assert.assertFalse(saveButton.isEnabled());
-        Assert.assertFalse(resetButton.isEnabled());
+        assertFalse(saveButton.isEnabled());
+        assertFalse(resetButton.isEnabled());
         verifyEventIsFired(eventIsFired);
 
         binder.validate();
         // no changes
-        Assert.assertFalse(saveButton.isEnabled());
-        Assert.assertFalse(resetButton.isEnabled());
+        assertFalse(saveButton.isEnabled());
+        assertFalse(resetButton.isEnabled());
         verifyEventIsFired(eventIsFired);
 
         field.setValue("");
         // binder is not bound, no event fired
         // no changes: see #375. There should be a change and disabled state for
         // save button because of failed validation
-        Assert.assertFalse(saveButton.isEnabled());
-        Assert.assertTrue(resetButton.isEnabled());
-        Assert.assertTrue(eventIsFired.get());
+        assertFalse(saveButton.isEnabled());
+        assertTrue(resetButton.isEnabled());
+        assertTrue(eventIsFired.get());
     }
 
     @Test
@@ -799,15 +803,15 @@ public class BinderBookOfVaadinTest {
                 .withValidator(new StringLengthValidator("", 1, 3))
                 .bind(BookPerson::getLastName, BookPerson::setLastName);
         // no changes
-        Assert.assertFalse(saveButton.isEnabled());
-        Assert.assertFalse(resetButton.isEnabled());
+        assertFalse(saveButton.isEnabled());
+        assertFalse(resetButton.isEnabled());
         verifyEventIsFired(eventIsFired);
 
         BookPerson person = new BookPerson(2000, 1);
         binder.setBean(person);
         // no changes
-        Assert.assertFalse(saveButton.isEnabled());
-        Assert.assertFalse(resetButton.isEnabled());
+        assertFalse(saveButton.isEnabled());
+        assertFalse(resetButton.isEnabled());
         verifyEventIsFired(eventIsFired);
 
         field.setValue("a");
@@ -816,8 +820,8 @@ public class BinderBookOfVaadinTest {
 
         field.setValue("");
         // there are invalid changes
-        Assert.assertFalse(saveButton.isEnabled());
-        Assert.assertTrue(resetButton.isEnabled());
+        assertFalse(saveButton.isEnabled());
+        assertTrue(resetButton.isEnabled());
         verifyEventIsFired(eventIsFired);
 
         // set valid value
@@ -825,8 +829,8 @@ public class BinderBookOfVaadinTest {
         verifyEventIsFired(eventIsFired);
         binder.writeBeanIfValid(person);
         // there are no changes.
-        Assert.assertFalse(saveButton.isEnabled());
-        Assert.assertFalse(resetButton.isEnabled());
+        assertFalse(saveButton.isEnabled());
+        assertFalse(resetButton.isEnabled());
         verifyEventIsFired(eventIsFired);
     }
 
@@ -846,13 +850,13 @@ public class BinderBookOfVaadinTest {
         binder.forField(emailField).asRequired("").bind(BookPerson::getEmail,
                 BookPerson::setEmail);
 
-        Assert.assertFalse(saveButton.isEnabled());
+        assertFalse(saveButton.isEnabled());
         field.setValue("not empty");
-        Assert.assertFalse(saveButton.isEnabled());
+        assertFalse(saveButton.isEnabled());
         emailField.setValue("not empty");
-        Assert.assertTrue(saveButton.isEnabled());
+        assertTrue(saveButton.isEnabled());
         field.clear();
-        Assert.assertFalse(saveButton.isEnabled());
+        assertFalse(saveButton.isEnabled());
     }
 
     @Test
@@ -881,7 +885,7 @@ public class BinderBookOfVaadinTest {
     }
 
     private void verifyEventIsFired(AtomicBoolean flag) {
-        Assert.assertTrue(flag.get());
+        assertTrue(flag.get());
         flag.set(false);
     }
 }
diff --git a/server/src/test/java/com/vaadin/data/BinderComponentTest.java b/server/src/test/java/com/vaadin/data/BinderComponentTest.java
index bf3d1a5074..776816be5e 100644
--- a/server/src/test/java/com/vaadin/data/BinderComponentTest.java
+++ b/server/src/test/java/com/vaadin/data/BinderComponentTest.java
@@ -1,8 +1,9 @@
 package com.vaadin.data;
 
+import static org.junit.Assert.assertEquals;
+
 import java.util.Collections;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -66,14 +67,14 @@ public class BinderComponentTest
     private <T> void testFieldNullRepresentation(T initialValue,
             HasValue<T> field) {
         binder.bind(field, t -> null, (str, val) -> {
-            Assert.assertEquals("Value update with initial value failed.",
+            assertEquals("Value update with initial value failed.",
                     initialValue, field.getValue());
         });
         field.setValue(initialValue);
-        Assert.assertEquals("Initial value of field unexpected", initialValue,
+        assertEquals("Initial value of field unexpected", initialValue,
                 field.getValue());
         binder.setBean(item);
-        Assert.assertEquals("Null representation for field failed",
+        assertEquals("Null representation for field failed",
                 field.getEmptyValue(), field.getValue());
         field.setValue(initialValue);
     }
diff --git a/server/src/test/java/com/vaadin/data/BinderConverterValidatorTest.java b/server/src/test/java/com/vaadin/data/BinderConverterValidatorTest.java
index 3ab4e962a0..4915bc9a5b 100644
--- a/server/src/test/java/com/vaadin/data/BinderConverterValidatorTest.java
+++ b/server/src/test/java/com/vaadin/data/BinderConverterValidatorTest.java
@@ -20,12 +20,12 @@ import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
 
 import java.io.Serializable;
 import java.util.List;
 import java.util.concurrent.atomic.AtomicBoolean;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -445,7 +445,7 @@ public class BinderConverterValidatorTest
             binder.writeBean(person);
         } finally {
             // Bean should not have been updated
-            Assert.assertEquals(firstName, person.getFirstName());
+            assertEquals(firstName, person.getFirstName());
         }
     }
 
@@ -463,7 +463,7 @@ public class BinderConverterValidatorTest
             binder.writeBean(person);
         } finally {
             // Bean should have been updated for item validation but reverted
-            Assert.assertNull(person.getFirstName());
+            assertNull(person.getFirstName());
         }
     }
 
@@ -479,8 +479,8 @@ public class BinderConverterValidatorTest
         person.setLastName("bar");
         nameField.setValue("foo");
         binder.writeBean(person);
-        Assert.assertEquals(nameField.getValue(), person.getFirstName());
-        Assert.assertEquals("bar", person.getLastName());
+        assertEquals(nameField.getValue(), person.getFirstName());
+        assertEquals("bar", person.getLastName());
     }
 
     @Test
@@ -492,8 +492,8 @@ public class BinderConverterValidatorTest
         Person person = new Person();
         person.setFirstName("foo");
         nameField.setValue("");
-        Assert.assertFalse(binder.writeBeanIfValid(person));
-        Assert.assertEquals("foo", person.getFirstName());
+        assertFalse(binder.writeBeanIfValid(person));
+        assertEquals("foo", person.getFirstName());
     }
 
     @Test
@@ -506,8 +506,8 @@ public class BinderConverterValidatorTest
         person.setFirstName("foo");
         nameField.setValue("bar");
 
-        Assert.assertTrue(binder.writeBeanIfValid(person));
-        Assert.assertEquals("bar", person.getFirstName());
+        assertTrue(binder.writeBeanIfValid(person));
+        assertEquals("bar", person.getFirstName());
     }
 
     @Test
@@ -524,9 +524,9 @@ public class BinderConverterValidatorTest
         Person person = new Person();
         person.setFirstName("foo");
         nameField.setValue("");
-        Assert.assertFalse(binder.writeBeanIfValid(person));
+        assertFalse(binder.writeBeanIfValid(person));
 
-        Assert.assertEquals("foo", person.getFirstName());
+        assertEquals("foo", person.getFirstName());
     }
 
     @Test
@@ -549,7 +549,7 @@ public class BinderConverterValidatorTest
 
         binder.writeBean(person);
 
-        Assert.assertNull(person.getFirstName());
+        assertNull(person.getFirstName());
     }
 
     @Test
@@ -569,19 +569,18 @@ public class BinderConverterValidatorTest
         ageField.setValue("-1");
         try {
             binder.writeBean(person);
-            Assert.fail();
+            fail();
         } catch (ValidationException exception) {
             List<BindingValidationStatus<?>> validationErrors = exception
                     .getFieldValidationErrors();
-            Assert.assertEquals(2, validationErrors.size());
+            assertEquals(2, validationErrors.size());
             BindingValidationStatus<?> error = validationErrors.get(0);
-            Assert.assertEquals(nameField, error.getField());
-            Assert.assertEquals(msg, error.getMessage().get());
+            assertEquals(nameField, error.getField());
+            assertEquals(msg, error.getMessage().get());
 
             error = validationErrors.get(1);
-            Assert.assertEquals(ageField, error.getField());
-            Assert.assertEquals(NEGATIVE_ERROR_MESSAGE,
-                    error.getMessage().get());
+            assertEquals(ageField, error.getField());
+            assertEquals(NEGATIVE_ERROR_MESSAGE, error.getMessage().get());
         }
     }
 
@@ -597,28 +596,28 @@ public class BinderConverterValidatorTest
         binder.setBean(person);
 
         // initial value is invalid but no error
-        Assert.assertNull(nameField.getComponentError());
+        assertNull(nameField.getComponentError());
 
         // make error show
         nameField.setValue("foo");
         nameField.setValue("");
-        Assert.assertNotNull(nameField.getComponentError());
+        assertNotNull(nameField.getComponentError());
 
         // bind to another person to see that error is cleared
         person = new Person();
         person.setFirstName("");
         binder.setBean(person);
         // error has been cleared
-        Assert.assertNull(nameField.getComponentError());
+        assertNull(nameField.getComponentError());
 
         // make show error
         nameField.setValue("foo");
         nameField.setValue("");
-        Assert.assertNotNull(nameField.getComponentError());
+        assertNotNull(nameField.getComponentError());
 
         // load should also clear error
         binder.readBean(person);
-        Assert.assertNull(nameField.getComponentError());
+        assertNull(nameField.getComponentError());
 
         // bind a new field that has invalid value in bean
         TextField lastNameField = new TextField();
@@ -628,7 +627,7 @@ public class BinderConverterValidatorTest
         binding2.bind(Person::getLastName, Person::setLastName);
 
         // should not have error shown
-        Assert.assertNull(lastNameField.getComponentError());
+        assertNull(lastNameField.getComponentError());
 
         // add status label to show bean level error
         Label statusLabel = new Label();
@@ -636,27 +635,27 @@ public class BinderConverterValidatorTest
         nameField.setValue("error");
 
         // no error shown yet because second field validation doesn't pass
-        Assert.assertEquals("", statusLabel.getValue());
+        assertEquals("", statusLabel.getValue());
 
         // make second field validation pass to get bean validation error
         lastNameField.setValue("foo");
-        Assert.assertEquals("error", statusLabel.getValue());
+        assertEquals("error", statusLabel.getValue());
 
         // reload bean to clear error
         binder.readBean(person);
-        Assert.assertEquals("", statusLabel.getValue());
+        assertEquals("", statusLabel.getValue());
 
         // reset() should clear all errors and status label
         nameField.setValue("");
         lastNameField.setValue("");
-        Assert.assertNotNull(nameField.getComponentError());
-        Assert.assertNotNull(lastNameField.getComponentError());
+        assertNotNull(nameField.getComponentError());
+        assertNotNull(lastNameField.getComponentError());
         statusLabel.setComponentError(new UserError("ERROR"));
 
         binder.removeBean();
-        Assert.assertNull(nameField.getComponentError());
-        Assert.assertNull(lastNameField.getComponentError());
-        Assert.assertEquals("", statusLabel.getValue());
+        assertNull(nameField.getComponentError());
+        assertNull(lastNameField.getComponentError());
+        assertEquals("", statusLabel.getValue());
     }
 
     @Test
@@ -682,18 +681,18 @@ public class BinderConverterValidatorTest
         Person person = new Person();
         binder.setBean(person);
 
-        Assert.assertNull(nameField.getComponentError());
-        Assert.assertNull(lastNameField.getComponentError());
+        assertNull(nameField.getComponentError());
+        assertNull(lastNameField.getComponentError());
 
         nameField.setValue("x");
 
-        Assert.assertNotNull(nameField.getComponentError());
-        Assert.assertNotNull(lastNameField.getComponentError());
+        assertNotNull(nameField.getComponentError());
+        assertNotNull(lastNameField.getComponentError());
 
         binder.setBean(person);
 
-        Assert.assertNull(nameField.getComponentError());
-        Assert.assertNull(lastNameField.getComponentError());
+        assertNull(nameField.getComponentError());
+        assertNull(lastNameField.getComponentError());
     }
 
     protected void bindName() {
@@ -724,7 +723,7 @@ public class BinderConverterValidatorTest
             binder.writeBean(person);
         } finally {
             // Bean should have been updated for item validation but reverted
-            Assert.assertEquals(0, person.getAge());
+            assertEquals(0, person.getAge());
         }
     }
 }
diff --git a/server/src/test/java/com/vaadin/data/BinderCustomPropertySetTest.java b/server/src/test/java/com/vaadin/data/BinderCustomPropertySetTest.java
index f9609aa47a..31c48447a6 100644
--- a/server/src/test/java/com/vaadin/data/BinderCustomPropertySetTest.java
+++ b/server/src/test/java/com/vaadin/data/BinderCustomPropertySetTest.java
@@ -15,13 +15,16 @@
  */
 package com.vaadin.data;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
 import java.util.HashMap;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Optional;
 import java.util.stream.Stream;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.server.Setter;
@@ -59,8 +62,8 @@ public class BinderCustomPropertySetTest {
         public Class<String> getType() {
             return String.class;
         }
-        
-        public Class<?> getPropertyHolderType(){
+
+        public Class<?> getPropertyHolderType() {
             return Map.class;
         }
 
@@ -116,7 +119,7 @@ public class BinderCustomPropertySetTest {
         binder.setBean(map);
 
         field.setValue("value");
-        Assert.assertEquals(
+        assertEquals(
                 "Field value should propagate to the corresponding key in the map",
                 "value", map.get("key"));
     }
@@ -130,17 +133,17 @@ public class BinderCustomPropertySetTest {
 
         binder.bindInstanceFields(instanceFields);
 
-        Assert.assertNotNull(
+        assertNotNull(
                 "Field corresponding to supported property name should be bound",
                 instanceFields.one);
-        Assert.assertNull(
+        assertNull(
                 "Field corresponding to unsupported property name should be ignored",
                 instanceFields.another);
 
         binder.setBean(map);
 
         instanceFields.one.setValue("value");
-        Assert.assertEquals(
+        assertEquals(
                 "Field value should propagate to the corresponding key in the map",
                 "value", map.get("one"));
     }
diff --git a/server/src/test/java/com/vaadin/data/BinderInstanceFieldTest.java b/server/src/test/java/com/vaadin/data/BinderInstanceFieldTest.java
index 5b2e0a2490..a05f2eaae4 100644
--- a/server/src/test/java/com/vaadin/data/BinderInstanceFieldTest.java
+++ b/server/src/test/java/com/vaadin/data/BinderInstanceFieldTest.java
@@ -15,9 +15,12 @@
  */
 package com.vaadin.data;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+
 import java.time.LocalDate;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.annotations.PropertyId;
@@ -147,14 +150,14 @@ public class BinderInstanceFieldTest {
 
         binder.setBean(person);
 
-        Assert.assertEquals(person.getFirstName(), form.firstName.getValue());
-        Assert.assertEquals(person.getBirthDate(), form.birthDate.getValue());
+        assertEquals(person.getFirstName(), form.firstName.getValue());
+        assertEquals(person.getBirthDate(), form.birthDate.getValue());
 
         form.firstName.setValue("bar");
         form.birthDate.setValue(person.getBirthDate().plusDays(345));
 
-        Assert.assertEquals(form.firstName.getValue(), person.getFirstName());
-        Assert.assertEquals(form.birthDate.getValue(), person.getBirthDate());
+        assertEquals(form.firstName.getValue(), person.getFirstName());
+        assertEquals(form.birthDate.getValue(), person.getBirthDate());
     }
 
     @Test(expected = IllegalStateException.class)
@@ -175,13 +178,13 @@ public class BinderInstanceFieldTest {
 
         binder.setBean(person);
 
-        Assert.assertEquals(person.getFirstName(), form.firstName.getValue());
+        assertEquals(person.getFirstName(), form.firstName.getValue());
 
-        Assert.assertNull(form.noFieldInPerson);
+        assertNull(form.noFieldInPerson);
 
         form.firstName.setValue("bar");
 
-        Assert.assertEquals(form.firstName.getValue(), person.getFirstName());
+        assertEquals(form.firstName.getValue(), person.getFirstName());
     }
 
     @Test
@@ -195,7 +198,7 @@ public class BinderInstanceFieldTest {
 
         binder.setBean(person);
 
-        Assert.assertNull(form.firstName);
+        assertNull(form.firstName);
     }
 
     @Test
@@ -209,11 +212,11 @@ public class BinderInstanceFieldTest {
 
         binder.setBean(person);
 
-        Assert.assertEquals(person.getFirstName(), form.firstName.getValue());
+        assertEquals(person.getFirstName(), form.firstName.getValue());
 
         form.firstName.setValue("bar");
 
-        Assert.assertEquals(form.firstName.getValue(), person.getFirstName());
+        assertEquals(form.firstName.getValue(), person.getFirstName());
     }
 
     @Test(expected = IllegalStateException.class)
@@ -269,11 +272,11 @@ public class BinderInstanceFieldTest {
 
         binder.setBean(person);
 
-        Assert.assertEquals(person.getFirstName(), form.firstName.getValue());
+        assertEquals(person.getFirstName(), form.firstName.getValue());
 
         form.firstName.setValue("bar");
 
-        Assert.assertEquals(form.firstName.getValue(), person.getFirstName());
+        assertEquals(form.firstName.getValue(), person.getFirstName());
     }
 
     @Test
@@ -289,7 +292,7 @@ public class BinderInstanceFieldTest {
 
         binder.setBean(person);
 
-        Assert.assertEquals(name, form.firstName);
+        assertEquals(name, form.firstName);
     }
 
     @Test
@@ -304,16 +307,14 @@ public class BinderInstanceFieldTest {
 
         binder.setBean(person);
 
-        Assert.assertEquals(person.getFirstName(), form.nameField.getValue());
-        Assert.assertEquals(person.getBirthDate(),
-                form.birthDateField.getValue());
+        assertEquals(person.getFirstName(), form.nameField.getValue());
+        assertEquals(person.getBirthDate(), form.birthDateField.getValue());
 
         form.nameField.setValue("bar");
         form.birthDateField.setValue(person.getBirthDate().plusDays(345));
 
-        Assert.assertEquals(form.nameField.getValue(), person.getFirstName());
-        Assert.assertEquals(form.birthDateField.getValue(),
-                person.getBirthDate());
+        assertEquals(form.nameField.getValue(), person.getFirstName());
+        assertEquals(form.birthDateField.getValue(), person.getBirthDate());
     }
 
     @Test
@@ -337,20 +338,20 @@ public class BinderInstanceFieldTest {
 
         binder.setBean(person);
 
-        Assert.assertEquals(person.getFirstName(), form.firstName.getValue());
-        Assert.assertEquals(person.getBirthDate(), form.birthDate.getValue());
+        assertEquals(person.getFirstName(), form.firstName.getValue());
+        assertEquals(person.getBirthDate(), form.birthDate.getValue());
         // the instance is not overridden
-        Assert.assertEquals(name, form.firstName);
+        assertEquals(name, form.firstName);
 
         // Test automatic binding
         form.birthDate.setValue(person.getBirthDate().plusDays(345));
-        Assert.assertEquals(form.birthDate.getValue(), person.getBirthDate());
+        assertEquals(form.birthDate.getValue(), person.getBirthDate());
 
         // Test custom binding
         form.firstName.setValue("aa");
-        Assert.assertEquals(personName, person.getFirstName());
+        assertEquals(personName, person.getFirstName());
 
-        Assert.assertFalse(binder.validate().isOk());
+        assertFalse(binder.validate().isOk());
     }
 
     @Test
@@ -380,24 +381,24 @@ public class BinderInstanceFieldTest {
 
         binder.setBean(person);
 
-        Assert.assertEquals(person.getFirstName(), form.firstName.getValue());
-        Assert.assertEquals(String.valueOf(person.getAge()),
+        assertEquals(person.getFirstName(), form.firstName.getValue());
+        assertEquals(String.valueOf(person.getAge()),
                 form.noFieldInPerson.getValue());
         // the instances are not overridden
-        Assert.assertEquals(name, form.firstName);
-        Assert.assertEquals(ageField, form.noFieldInPerson);
+        assertEquals(name, form.firstName);
+        assertEquals(ageField, form.noFieldInPerson);
 
         // Test correct age
         age += 56;
         form.noFieldInPerson.setValue(String.valueOf(age));
-        Assert.assertEquals(form.noFieldInPerson.getValue(),
+        assertEquals(form.noFieldInPerson.getValue(),
                 String.valueOf(person.getAge()));
 
         // Test incorrect name
         form.firstName.setValue("aa");
-        Assert.assertEquals(personName, person.getFirstName());
+        assertEquals(personName, person.getFirstName());
 
-        Assert.assertFalse(binder.validate().isOk());
+        assertFalse(binder.validate().isOk());
     }
 
     @Test
@@ -415,7 +416,7 @@ public class BinderInstanceFieldTest {
         person.setFirstName("first");
         person.setAge(45);
         binder.setBean(person);
-        Assert.assertEquals("90", form.age.getValue());
+        assertEquals("90", form.age.getValue());
     }
 
     @Test
diff --git a/server/src/test/java/com/vaadin/data/BinderStatusChangeTest.java b/server/src/test/java/com/vaadin/data/BinderStatusChangeTest.java
index 1ab39ee46f..f2cb147e70 100644
--- a/server/src/test/java/com/vaadin/data/BinderStatusChangeTest.java
+++ b/server/src/test/java/com/vaadin/data/BinderStatusChangeTest.java
@@ -15,9 +15,12 @@
  */
 package com.vaadin.data;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
 import java.util.concurrent.atomic.AtomicReference;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -49,7 +52,7 @@ public class BinderStatusChangeTest
         BindingBuilder<Person, String> binding = binder.forField(nameField);
 
         nameField.setValue("");
-        Assert.assertNull(event.get());
+        assertNull(event.get());
 
         binding.bind(Person::getFirstName, Person::setFirstName);
         verifyEvent();
@@ -59,7 +62,7 @@ public class BinderStatusChangeTest
     public void bindBinder_unbound_singleEventWhenBound() {
         binder.addStatusChangeListener(this::statusChanged);
 
-        Assert.assertNull(event.get());
+        assertNull(event.get());
 
         binder.setBean(item);
 
@@ -72,7 +75,7 @@ public class BinderStatusChangeTest
 
         binder.addStatusChangeListener(this::statusChanged);
 
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         binder.removeBean();
         verifyEvent();
     }
@@ -81,9 +84,9 @@ public class BinderStatusChangeTest
     public void removeBean_unbound_noEventWhenUnBound() {
         binder.addStatusChangeListener(this::statusChanged);
 
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         binder.removeBean();
-        Assert.assertNull(event.get());
+        assertNull(event.get());
     }
 
     @Test
@@ -94,7 +97,7 @@ public class BinderStatusChangeTest
 
         binder.addStatusChangeListener(this::statusChanged);
 
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         nameField.setValue("foo");
         verifyEvent();
     }
@@ -110,7 +113,7 @@ public class BinderStatusChangeTest
 
         binder.addStatusChangeListener(this::statusChanged);
 
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         nameField.setValue("foo");
         verifyEvent();
     }
@@ -123,7 +126,7 @@ public class BinderStatusChangeTest
 
         binder.addStatusChangeListener(this::statusChanged);
 
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         nameField.setValue("foo");
         verifyEvent(true);
     }
@@ -138,7 +141,7 @@ public class BinderStatusChangeTest
 
         binder.addStatusChangeListener(this::statusChanged);
 
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         nameField.setValue("foo");
         verifyEvent(true);
     }
@@ -148,7 +151,7 @@ public class BinderStatusChangeTest
         binder.forField(nameField).bind(Person::getFirstName,
                 Person::setFirstName);
         binder.addStatusChangeListener(this::statusChanged);
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         binder.readBean(item);
         verifyEvent();
     }
@@ -161,7 +164,7 @@ public class BinderStatusChangeTest
                 .withConverter(new StringToIntegerConverter(""))
                 .bind(Person::getAge, Person::setAge);
         binder.addStatusChangeListener(this::statusChanged);
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         binder.readBean(item);
         verifyEvent();
     }
@@ -169,7 +172,7 @@ public class BinderStatusChangeTest
     @Test
     public void readBean_hasNoBindings_singleEvent() {
         binder.addStatusChangeListener(this::statusChanged);
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         binder.readBean(item);
         verifyEvent();
     }
@@ -178,7 +181,7 @@ public class BinderStatusChangeTest
     public void writeBean_hasNoBindings_singleEvent()
             throws ValidationException {
         binder.addStatusChangeListener(this::statusChanged);
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         binder.writeBean(item);
         verifyEvent();
     }
@@ -186,7 +189,7 @@ public class BinderStatusChangeTest
     @Test
     public void writeBeanIfValid_hasNoBindings_singleEvent() {
         binder.addStatusChangeListener(this::statusChanged);
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         binder.writeBeanIfValid(item);
         verifyEvent();
     }
@@ -198,7 +201,7 @@ public class BinderStatusChangeTest
         binder.readBean(item);
 
         binder.addStatusChangeListener(this::statusChanged);
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         binder.writeBean(item);
         verifyEvent();
     }
@@ -214,7 +217,7 @@ public class BinderStatusChangeTest
         binder.readBean(item);
 
         binder.addStatusChangeListener(this::statusChanged);
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         binder.writeBean(item);
         verifyEvent();
     }
@@ -226,7 +229,7 @@ public class BinderStatusChangeTest
         binder.readBean(item);
 
         binder.addStatusChangeListener(this::statusChanged);
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         binder.writeBeanIfValid(item);
         verifyEvent();
     }
@@ -241,7 +244,7 @@ public class BinderStatusChangeTest
         binder.readBean(item);
 
         binder.addStatusChangeListener(this::statusChanged);
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         binder.writeBeanIfValid(item);
         verifyEvent();
     }
@@ -253,7 +256,7 @@ public class BinderStatusChangeTest
         binder.readBean(item);
 
         binder.addStatusChangeListener(this::statusChanged);
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         try {
             binder.writeBean(item);
         } catch (ValidationException ignore) {
@@ -268,7 +271,7 @@ public class BinderStatusChangeTest
         binder.readBean(item);
 
         binder.addStatusChangeListener(this::statusChanged);
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         binder.writeBeanIfValid(item);
         verifyEvent(true);
     }
@@ -283,7 +286,7 @@ public class BinderStatusChangeTest
         binder.readBean(item);
 
         binder.addStatusChangeListener(this::statusChanged);
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         binder.writeBeanIfValid(item);
         verifyEvent(true);
     }
@@ -296,7 +299,7 @@ public class BinderStatusChangeTest
         binder.withValidator(Validator.from(person -> false, ""));
 
         binder.addStatusChangeListener(this::statusChanged);
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         try {
             binder.writeBean(item);
         } catch (ValidationException ignore) {
@@ -312,7 +315,7 @@ public class BinderStatusChangeTest
         binder.withValidator(Validator.from(person -> false, ""));
 
         binder.addStatusChangeListener(this::statusChanged);
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         binder.writeBeanIfValid(item);
         verifyEvent(true);
     }
@@ -326,7 +329,7 @@ public class BinderStatusChangeTest
         binder.withValidator(Validator.from(person -> true, ""));
 
         binder.addStatusChangeListener(this::statusChanged);
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         binder.writeBean(item);
         verifyEvent();
     }
@@ -339,7 +342,7 @@ public class BinderStatusChangeTest
         binder.withValidator(Validator.from(person -> true, ""));
 
         binder.addStatusChangeListener(this::statusChanged);
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         binder.writeBeanIfValid(item);
         verifyEvent();
     }
@@ -354,7 +357,7 @@ public class BinderStatusChangeTest
         binder.setBean(item);
 
         binder.addStatusChangeListener(this::statusChanged);
-        Assert.assertNull(event.get());
+        assertNull(event.get());
 
         binder.validate();
         verifyEvent();
@@ -370,7 +373,7 @@ public class BinderStatusChangeTest
         binder.setBean(item);
 
         binder.addStatusChangeListener(this::statusChanged);
-        Assert.assertNull(event.get());
+        assertNull(event.get());
 
         binder.validate();
         verifyEvent(true);
@@ -386,7 +389,7 @@ public class BinderStatusChangeTest
         binder.setBean(item);
 
         binder.addStatusChangeListener(this::statusChanged);
-        Assert.assertNull(event.get());
+        assertNull(event.get());
 
         binding.validate();
         verifyEvent();
@@ -403,7 +406,7 @@ public class BinderStatusChangeTest
         binder.setBean(item);
 
         binder.addStatusChangeListener(this::statusChanged);
-        Assert.assertNull(event.get());
+        assertNull(event.get());
 
         binding.validate();
         verifyEvent(true);
@@ -415,15 +418,14 @@ public class BinderStatusChangeTest
 
     private void verifyEvent(boolean validationErrors) {
         StatusChangeEvent statusChangeEvent = event.get();
-        Assert.assertNotNull(statusChangeEvent);
-        Assert.assertEquals(binder, statusChangeEvent.getBinder());
-        Assert.assertEquals(binder, statusChangeEvent.getSource());
-        Assert.assertEquals(validationErrors,
-                statusChangeEvent.hasValidationErrors());
+        assertNotNull(statusChangeEvent);
+        assertEquals(binder, statusChangeEvent.getBinder());
+        assertEquals(binder, statusChangeEvent.getSource());
+        assertEquals(validationErrors, statusChangeEvent.hasValidationErrors());
     }
 
     private void statusChanged(StatusChangeEvent evt) {
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         event.set(evt);
     }
 }
diff --git a/server/src/test/java/com/vaadin/data/BinderTest.java b/server/src/test/java/com/vaadin/data/BinderTest.java
index 36d1692fcb..1169eb8a5d 100644
--- a/server/src/test/java/com/vaadin/data/BinderTest.java
+++ b/server/src/test/java/com/vaadin/data/BinderTest.java
@@ -1,7 +1,9 @@
 package com.vaadin.data;
 
+import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertSame;
@@ -12,7 +14,6 @@ import java.util.Objects;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.stream.Stream;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -232,7 +233,7 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
 
         binder.writeBean(person);
 
-        Assert.assertEquals(age, person.getAge());
+        assertEquals(age, person.getAge());
     }
 
     @Test
@@ -249,7 +250,7 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
 
         binder.writeBean(person);
 
-        Assert.assertEquals(fieldValue, person.getFirstName());
+        assertEquals(fieldValue, person.getFirstName());
     }
 
     @Test
@@ -262,7 +263,7 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
         person.setFirstName(name);
         binder.readBean(person);
 
-        Assert.assertEquals(name, nameField.getValue());
+        assertEquals(name, nameField.getValue());
     }
 
     @Test
@@ -275,7 +276,7 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
         person.setFirstName(name);
         binder.readBean(person);
 
-        Assert.assertEquals("", nameField.getValue());
+        assertEquals("", nameField.getValue());
     }
 
     protected void bindName() {
@@ -296,19 +297,19 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
         // Bind a person with null value and check that null representation is
         // used
         binder.setBean(namelessPerson);
-        Assert.assertEquals(
+        assertEquals(
                 "Null value from bean was not converted to explicit null representation",
                 nullRepresentation, nameField.getValue());
 
         // Verify that changes are applied to bean
         nameField.setValue(realName);
-        Assert.assertEquals(
+        assertEquals(
                 "Bean was not correctly updated from a change in the field",
                 realName, namelessPerson.getFirstName());
 
         // Verify conversion back to null
         nameField.setValue(nullRepresentation);
-        Assert.assertEquals(
+        assertEquals(
                 "Two-way null representation did not change value back to null",
                 null, namelessPerson.getFirstName());
     }
@@ -328,19 +329,19 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
         binder.setBean(namelessPerson);
 
         assertTrue(nullTextField.isEmpty());
-        Assert.assertEquals(null, namelessPerson.getFirstName());
+        assertEquals(null, namelessPerson.getFirstName());
 
         // Change value, see that textfield is not empty and bean is updated.
         nullTextField.setValue("");
         assertFalse(nullTextField.isEmpty());
-        Assert.assertEquals("First name of person was not properly updated", "",
+        assertEquals("First name of person was not properly updated", "",
                 namelessPerson.getFirstName());
 
         // Verify that default null representation does not map back to null
         nullTextField.setValue("null");
         assertTrue(nullTextField.isEmpty());
-        Assert.assertEquals("Default one-way null representation failed.",
-                "null", namelessPerson.getFirstName());
+        assertEquals("Default one-way null representation failed.", "null",
+                namelessPerson.getFirstName());
     }
 
     @Test
@@ -354,8 +355,8 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
                 Objects.isNull(item.getFirstName()));
         binder.setBean(item);
 
-        Assert.assertEquals("Field value was not set correctly",
-                item.getFirstName(), nameField.getValue());
+        assertEquals("Field value was not set correctly", item.getFirstName(),
+                nameField.getValue());
     }
 
     @Test
@@ -368,12 +369,11 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
                 .bind(Person::getSalary, Person::setSalary);
         binder.setBean(item);
 
-        Assert.assertEquals(customNullConverter.toString(),
-                ageField.getValue());
+        assertEquals(customNullConverter.toString(), ageField.getValue());
 
         Integer salary = 11;
         ageField.setValue(salary.toString());
-        Assert.assertEquals(11, salary.intValue());
+        assertEquals(11, salary.intValue());
     }
 
     @Test
@@ -384,7 +384,7 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
         Person person = new Person();
         binder.setBean(person);
 
-        Assert.assertEquals("", nameField.getValue());
+        assertEquals("", nameField.getValue());
     }
 
     @Test
@@ -392,15 +392,15 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
         String customNullPointerRepresentation = "foo";
         Binder<Person> binder = new Binder<>(Person.class);
         binder.forField(nameField)
-                .withConverter(value -> value, value -> value == null
-                        ? customNullPointerRepresentation : value)
+                .withConverter(value -> value,
+                        value -> value == null ? customNullPointerRepresentation
+                                : value)
                 .bind("firstName");
 
         Person person = new Person();
         binder.setBean(person);
 
-        Assert.assertEquals(customNullPointerRepresentation,
-                nameField.getValue());
+        assertEquals(customNullPointerRepresentation, nameField.getValue());
     }
 
     @Test
@@ -412,11 +412,11 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
         item.setFirstName(null);
         binder.setBean(item);
 
-        Assert.assertEquals(nullRepresentation, nameField.getValue());
+        assertEquals(nullRepresentation, nameField.getValue());
 
         String newValue = "bar";
         nameField.setValue(newValue);
-        Assert.assertEquals(newValue, item.getFirstName());
+        assertEquals(newValue, item.getFirstName());
     }
 
     @Test
@@ -432,15 +432,15 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
 
         binding.bind(Person::getFirstName, Person::setFirstName);
         binder.setBean(item);
-        Assert.assertNull(textField.getErrorMessage());
+        assertNull(textField.getErrorMessage());
 
         textField.setValue(textField.getEmptyValue());
         ErrorMessage errorMessage = textField.getErrorMessage();
-        Assert.assertNotNull(errorMessage);
-        Assert.assertEquals("foobar", errorMessage.getFormattedHtmlMessage());
+        assertNotNull(errorMessage);
+        assertEquals("foobar", errorMessage.getFormattedHtmlMessage());
 
         textField.setValue("value");
-        Assert.assertNull(textField.getErrorMessage());
+        assertNull(textField.getErrorMessage());
         assertTrue(textField.isRequiredIndicatorVisible());
     }
 
@@ -449,19 +449,19 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
         TextField textField = new TextField();
         binder.forField(textField).asRequired("foobar")
                 .bind(Person::getFirstName, Person::setFirstName);
-        Assert.assertTrue(textField.isRequiredIndicatorVisible());
-        Assert.assertNull(textField.getErrorMessage());
+        assertTrue(textField.isRequiredIndicatorVisible());
+        assertNull(textField.getErrorMessage());
 
         binder.readBean(item);
-        Assert.assertNull(textField.getErrorMessage());
+        assertNull(textField.getErrorMessage());
 
         textField.setValue(textField.getEmptyValue());
-        Assert.assertTrue(textField.isRequiredIndicatorVisible());
-        Assert.assertNotNull(textField.getErrorMessage());
+        assertTrue(textField.isRequiredIndicatorVisible());
+        assertNotNull(textField.getErrorMessage());
 
         binder.readBean(null);
         assertTrue(textField.isRequiredIndicatorVisible());
-        Assert.assertNull(textField.getErrorMessage());
+        assertNull(textField.getErrorMessage());
     }
 
     @Test
@@ -476,25 +476,25 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
 
         binding.asRequired(context -> {
             invokes.incrementAndGet();
-            Assert.assertSame(Locale.CANADA, context.getLocale().get());
+            assertSame(Locale.CANADA, context.getLocale().get());
             return "foobar";
         });
         assertTrue(textField.isRequiredIndicatorVisible());
 
         binding.bind(Person::getFirstName, Person::setFirstName);
         binder.setBean(item);
-        Assert.assertNull(textField.getErrorMessage());
-        Assert.assertEquals(0, invokes.get());
+        assertNull(textField.getErrorMessage());
+        assertEquals(0, invokes.get());
 
         textField.setValue(textField.getEmptyValue());
         ErrorMessage errorMessage = textField.getErrorMessage();
-        Assert.assertNotNull(errorMessage);
-        Assert.assertEquals("foobar", errorMessage.getFormattedHtmlMessage());
+        assertNotNull(errorMessage);
+        assertEquals("foobar", errorMessage.getFormattedHtmlMessage());
         // validation is done for the whole bean at once.
-        Assert.assertEquals(1, invokes.get());
+        assertEquals(1, invokes.get());
 
         textField.setValue("value");
-        Assert.assertNull(textField.getErrorMessage());
+        assertNull(textField.getErrorMessage());
         assertTrue(textField.isRequiredIndicatorVisible());
     }
 
@@ -516,13 +516,13 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
 
         binder.setBean(item);
         // setting the bean causes 2:
-        Assert.assertEquals(2, invokes.get());
+        assertEquals(2, invokes.get());
 
         lastNameField.setValue("");
-        Assert.assertEquals(2, invokes.get());
+        assertEquals(2, invokes.get());
 
         firstNameField.setValue("");
-        Assert.assertEquals(3, invokes.get());
+        assertEquals(3, invokes.get());
 
         binder.removeBean();
         Person person = new Person();
@@ -530,13 +530,13 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
         person.setLastName("a");
         binder.readBean(person);
         // reading from a bean causes 2:
-        Assert.assertEquals(5, invokes.get());
+        assertEquals(5, invokes.get());
 
         lastNameField.setValue("");
-        Assert.assertEquals(5, invokes.get());
+        assertEquals(5, invokes.get());
 
         firstNameField.setValue("");
-        Assert.assertEquals(6, invokes.get());
+        assertEquals(6, invokes.get());
     }
 
     @Test(expected = IllegalStateException.class)
@@ -619,16 +619,16 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
 
         binder.setBean(item);
 
-        Assert.assertTrue(binder.isValid());
+        assertTrue(binder.isValid());
 
         nameField.setValue("fail field validation");
-        Assert.assertFalse(binder.isValid());
+        assertFalse(binder.isValid());
 
         nameField.setValue("");
-        Assert.assertTrue(binder.isValid());
+        assertTrue(binder.isValid());
 
         nameField.setValue("fail bean validation");
-        Assert.assertFalse(binder.isValid());
+        assertFalse(binder.isValid());
     }
 
     @Test
@@ -638,13 +638,13 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
                         name -> !name.equals("fail field validation"), ""))
                 .bind(Person::getFirstName, Person::setFirstName);
 
-        Assert.assertTrue(binder.isValid());
+        assertTrue(binder.isValid());
 
         nameField.setValue("fail field validation");
-        Assert.assertFalse(binder.isValid());
+        assertFalse(binder.isValid());
 
         nameField.setValue("");
-        Assert.assertTrue(binder.isValid());
+        assertTrue(binder.isValid());
     }
 
     @Test(expected = IllegalStateException.class)
@@ -659,7 +659,7 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
 
     @Test
     public void getFields_returnsFields() {
-        Assert.assertEquals(0, binder.getFields().count());
+        assertEquals(0, binder.getFields().count());
         binder.forField(nameField).bind(Person::getFirstName,
                 Person::setFirstName);
         assertStreamEquals(Stream.of(nameField), binder.getFields());
@@ -670,7 +670,7 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
     }
 
     private void assertStreamEquals(Stream<?> s1, Stream<?> s2) {
-        Assert.assertArrayEquals(s1.toArray(), s2.toArray());
+        assertArrayEquals(s1.toArray(), s2.toArray());
     }
 
     @Test
@@ -691,23 +691,23 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
 
         ageField.setValue("123123");
         validation = bind.validate();
-        Assert.assertTrue(validation.isError());
-        Assert.assertEquals(stringLength, validation.getMessage().get());
+        assertTrue(validation.isError());
+        assertEquals(stringLength, validation.getMessage().get());
 
         ageField.setValue("age");
         validation = bind.validate();
-        Assert.assertTrue(validation.isError());
-        Assert.assertEquals(conversion, validation.getMessage().get());
+        assertTrue(validation.isError());
+        assertEquals(conversion, validation.getMessage().get());
 
         ageField.setValue("256");
         validation = bind.validate();
-        Assert.assertTrue(validation.isError());
-        Assert.assertEquals(ageLimit, validation.getMessage().get());
+        assertTrue(validation.isError());
+        assertEquals(ageLimit, validation.getMessage().get());
 
         ageField.setValue("30");
         validation = bind.validate();
-        Assert.assertFalse(validation.isError());
-        Assert.assertEquals(30, item.getAge());
+        assertFalse(validation.isError());
+        assertEquals(30, item.getAge());
     }
 
     @Test
@@ -717,19 +717,19 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
                 .bind(Person::getAge, Person::setAge);
 
         // Test that the binding does work
-        Assert.assertTrue("Field not initially empty", ageField.isEmpty());
+        assertTrue("Field not initially empty", ageField.isEmpty());
         binder.setBean(item);
-        Assert.assertEquals("Binding did not work",
-                String.valueOf(item.getAge()), ageField.getValue());
+        assertEquals("Binding did not work", String.valueOf(item.getAge()),
+                ageField.getValue());
         binder.setBean(null);
-        Assert.assertTrue("Field not cleared", ageField.isEmpty());
+        assertTrue("Field not cleared", ageField.isEmpty());
 
         // Remove the binding
         binder.removeBinding(ageField);
 
         // Test that it does not work anymore
         binder.setBean(item);
-        Assert.assertNotEquals("Binding was not removed",
+        assertNotEquals("Binding was not removed",
                 String.valueOf(item.getAge()), ageField.getValue());
     }
 
@@ -741,19 +741,19 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
         binder.bind(nameField, "firstName");
 
         // Test that the binding does work
-        Assert.assertTrue("Field not initially empty", nameField.isEmpty());
+        assertTrue("Field not initially empty", nameField.isEmpty());
         binder.setBean(item);
-        Assert.assertEquals("Binding did not work", item.getFirstName(),
+        assertEquals("Binding did not work", item.getFirstName(),
                 nameField.getValue());
         binder.setBean(null);
-        Assert.assertTrue("Field not cleared", nameField.isEmpty());
+        assertTrue("Field not cleared", nameField.isEmpty());
 
         // Remove the binding
         binder.removeBinding("firstName");
 
         // Test that it does not work anymore
         binder.setBean(item);
-        Assert.assertNotEquals("Binding was not removed", item.getFirstName(),
+        assertNotEquals("Binding was not removed", item.getFirstName(),
                 nameField.getValue());
     }
 
@@ -764,19 +764,19 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
                 .bind(Person::getAge, Person::setAge);
 
         // Test that the binding does work
-        Assert.assertTrue("Field not initially empty", ageField.isEmpty());
+        assertTrue("Field not initially empty", ageField.isEmpty());
         binder.setBean(item);
-        Assert.assertEquals("Binding did not work",
-                String.valueOf(item.getAge()), ageField.getValue());
+        assertEquals("Binding did not work", String.valueOf(item.getAge()),
+                ageField.getValue());
         binder.setBean(null);
-        Assert.assertTrue("Field not cleared", ageField.isEmpty());
+        assertTrue("Field not cleared", ageField.isEmpty());
 
         // Remove the binding
         binder.removeBinding(binding);
 
         // Test that it does not work anymore
         binder.setBean(item);
-        Assert.assertNotEquals("Binding was not removed",
+        assertNotEquals("Binding was not removed",
                 String.valueOf(item.getAge()), ageField.getValue());
     }
 
@@ -788,38 +788,33 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
         item.setLastName("Valid");
         binder.setBean(item);
 
-        Assert.assertFalse("Should not have changes initially",
-                binder.hasChanges());
-        Assert.assertTrue("Should be ok initially", binder.validate().isOk());
-        Assert.assertNotEquals(
-                "First name and last name are not same initially",
+        assertFalse("Should not have changes initially", binder.hasChanges());
+        assertTrue("Should be ok initially", binder.validate().isOk());
+        assertNotEquals("First name and last name are not same initially",
                 item.getFirstName(), item.getLastName());
 
         nameField.setValue("Invalid");
 
-        Assert.assertFalse("First name change not handled",
-                binder.hasChanges());
-        Assert.assertTrue(
+        assertFalse("First name change not handled", binder.hasChanges());
+        assertTrue(
                 "Changing first name to something else than last name should be ok",
                 binder.validate().isOk());
 
         lastNameField.setValue("Invalid");
 
-        Assert.assertTrue("Last name should not be saved yet",
-                binder.hasChanges());
-        Assert.assertFalse(
-                "Binder validation should fail with pending illegal value",
+        assertTrue("Last name should not be saved yet", binder.hasChanges());
+        assertFalse("Binder validation should fail with pending illegal value",
                 binder.validate().isOk());
-        Assert.assertNotEquals("Illegal last name should not be stored to bean",
+        assertNotEquals("Illegal last name should not be stored to bean",
                 item.getFirstName(), item.getLastName());
 
         nameField.setValue("Valid");
 
-        Assert.assertFalse("With new first name both changes should be saved",
+        assertFalse("With new first name both changes should be saved",
                 binder.hasChanges());
-        Assert.assertTrue("Everything should be ok for 'Valid Invalid'",
+        assertTrue("Everything should be ok for 'Valid Invalid'",
                 binder.validate().isOk());
-        Assert.assertNotEquals("First name and last name should never match.",
+        assertNotEquals("First name and last name should never match.",
                 item.getFirstName(), item.getLastName());
     }
 
@@ -831,8 +826,8 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
         item.setLastName(item.getFirstName());
         binder.setBean(item);
 
-        Assert.assertFalse(binder.isValid());
-        Assert.assertFalse(binder.validate().isOk());
+        assertFalse(binder.isValid());
+        assertFalse(binder.validate().isOk());
     }
 
     @Test(expected = IllegalStateException.class)
@@ -842,7 +837,7 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
 
         binder.readBean(item);
 
-        Assert.assertTrue(binder.isValid());
+        assertTrue(binder.isValid());
     }
 
     @Test(expected = IllegalStateException.class)
@@ -852,7 +847,7 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
 
         binder.readBean(item);
 
-        Assert.assertTrue(binder.validate().isOk());
+        assertTrue(binder.validate().isOk());
     }
 
     protected void setBeanValidationFirstNameNotEqualsLastName(
@@ -876,9 +871,9 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
         public void statusChange(BindingValidationStatus<?> statusChange) {
             ++callCount;
             if (expectingError) {
-                Assert.assertTrue("Expecting error", statusChange.isError());
+                assertTrue("Expecting error", statusChange.isError());
             } else {
-                Assert.assertFalse("Unexpected error", statusChange.isError());
+                assertFalse("Unexpected error", statusChange.isError());
             }
         }
     }
@@ -911,20 +906,20 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
 
         // Test default error handling.
         ageField.setValue("foo");
-        Assert.assertTrue("Component error does not contain error message",
+        assertTrue("Component error does not contain error message",
                 ageField.getComponentError().getFormattedHtmlMessage()
                         .contains(ageError));
 
         // Restore values and test no errors.
         ageField.setValue(String.valueOf(initialAge));
-        Assert.assertNull("There should be no component error",
+        assertNull("There should be no component error",
                 ageField.getComponentError());
 
         bindingHandler.expectingError = false;
         nameField.setValue(initialName);
 
         // Assert that the handler was called.
-        Assert.assertEquals(
+        assertEquals(
                 "Unexpected callCount to binding validation status handler", 6,
                 bindingHandler.callCount);
     }
@@ -944,7 +939,7 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
 
         ageField.setValue(modifiedAge);
 
-        Assert.assertEquals("Binding still affects bean even after unbind",
+        assertEquals("Binding still affects bean even after unbind",
                 ageBeforeUnbind, String.valueOf(item.getAge()));
     }
 }
diff --git a/server/src/test/java/com/vaadin/data/BinderValidationStatusTest.java b/server/src/test/java/com/vaadin/data/BinderValidationStatusTest.java
index 6e1f7614bb..dcf568cafc 100644
--- a/server/src/test/java/com/vaadin/data/BinderValidationStatusTest.java
+++ b/server/src/test/java/com/vaadin/data/BinderValidationStatusTest.java
@@ -15,10 +15,17 @@
  */
 package com.vaadin.data;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
 import java.util.List;
 import java.util.concurrent.atomic.AtomicReference;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -51,7 +58,7 @@ public class BinderValidationStatusTest
         AtomicReference<BindingValidationStatus<?>> statusCapture = new AtomicReference<>();
         BindingBuilder<Person, String> binding = binder.forField(nameField)
                 .withValidator(notEmpty).withValidationStatusHandler(evt -> {
-                    Assert.assertNull(statusCapture.get());
+                    assertNull(statusCapture.get());
                     statusCapture.set(evt);
                 });
         binding.bind(Person::getFirstName, Person::setFirstName);
@@ -62,11 +69,11 @@ public class BinderValidationStatusTest
         // message
         binder.validate();
 
-        Assert.assertNotNull(statusCapture.get());
+        assertNotNull(statusCapture.get());
         BindingValidationStatus<?> evt = statusCapture.get();
-        Assert.assertEquals(Status.ERROR, evt.getStatus());
-        Assert.assertEquals(EMPTY_ERROR_MESSAGE, evt.getMessage().get());
-        Assert.assertEquals(nameField, evt.getField());
+        assertEquals(Status.ERROR, evt.getStatus());
+        assertEquals(EMPTY_ERROR_MESSAGE, evt.getMessage().get());
+        assertEquals(nameField, evt.getField());
 
         statusCapture.set(null);
         nameField.setValue("foo");
@@ -77,10 +84,10 @@ public class BinderValidationStatusTest
         binder.validate();
 
         evt = statusCapture.get();
-        Assert.assertNotNull(evt);
-        Assert.assertEquals(Status.OK, evt.getStatus());
-        Assert.assertFalse(evt.getMessage().isPresent());
-        Assert.assertEquals(nameField, evt.getField());
+        assertNotNull(evt);
+        assertEquals(Status.OK, evt.getStatus());
+        assertFalse(evt.getMessage().isPresent());
+        assertEquals(nameField, evt.getField());
     }
 
     @Test
@@ -89,7 +96,7 @@ public class BinderValidationStatusTest
                 .withValidator(notEmpty).withValidationStatusHandler(evt -> {
                 }).bind(Person::getFirstName, Person::setFirstName);
 
-        Assert.assertNull(nameField.getComponentError());
+        assertNull(nameField.getComponentError());
 
         nameField.setValue("");
 
@@ -98,7 +105,7 @@ public class BinderValidationStatusTest
         binding.validate();
 
         // default behavior should update component error for the nameField
-        Assert.assertNull(nameField.getComponentError());
+        assertNull(nameField.getComponentError());
     }
 
     @Test
@@ -115,8 +122,8 @@ public class BinderValidationStatusTest
         // message
         binding.validate();
 
-        Assert.assertTrue(label.isVisible());
-        Assert.assertEquals(EMPTY_ERROR_MESSAGE, label.getValue());
+        assertTrue(label.isVisible());
+        assertEquals(EMPTY_ERROR_MESSAGE, label.getValue());
 
         nameField.setValue("foo");
 
@@ -124,8 +131,8 @@ public class BinderValidationStatusTest
         // no message
         binding.validate();
 
-        Assert.assertFalse(label.isVisible());
-        Assert.assertEquals("", label.getValue());
+        assertFalse(label.isVisible());
+        assertEquals("", label.getValue());
     }
 
     @Test
@@ -136,7 +143,7 @@ public class BinderValidationStatusTest
                 .withValidator(notEmpty).withStatusLabel(label)
                 .bind(Person::getFirstName, Person::setFirstName);
 
-        Assert.assertNull(nameField.getComponentError());
+        assertNull(nameField.getComponentError());
 
         nameField.setValue("");
 
@@ -145,7 +152,7 @@ public class BinderValidationStatusTest
         binding.validate();
 
         // default behavior should update component error for the nameField
-        Assert.assertNull(nameField.getComponentError());
+        assertNull(nameField.getComponentError());
     }
 
     @Test(expected = IllegalStateException.class)
@@ -154,7 +161,7 @@ public class BinderValidationStatusTest
                 .withValidator(notEmpty);
         binding.bind(Person::getFirstName, Person::setFirstName);
 
-        binding.withValidationStatusHandler(evt -> Assert.fail());
+        binding.withValidationStatusHandler(evt -> fail());
     }
 
     @Test(expected = IllegalStateException.class)
@@ -209,20 +216,18 @@ public class BinderValidationStatusTest
         AtomicReference<BinderValidationStatus<?>> statusCapture = new AtomicReference<>();
         binder.forField(nameField).withValidator(notEmpty)
                 .withValidationStatusHandler(evt -> {
-                    Assert.fail(
-                            "Using a custom status change handler so no change should end up here");
+                    fail("Using a custom status change handler so no change should end up here");
                 }).bind(Person::getFirstName, Person::setFirstName);
         binder.forField(ageField).withConverter(stringToInteger)
                 .withValidator(notNegative).withValidationStatusHandler(evt -> {
-                    Assert.fail(
-                            "Using a custom status change handler so no change should end up here");
+                    fail("Using a custom status change handler so no change should end up here");
                 }).bind(Person::getAge, Person::setAge);
 
         binder.setValidationStatusHandler(r -> {
             statusCapture.set(r);
         });
         binder.setBean(item);
-        Assert.assertNull(nameField.getComponentError());
+        assertNull(nameField.getComponentError());
 
         nameField.setValue("");
         ageField.setValue("5");
@@ -231,28 +236,28 @@ public class BinderValidationStatusTest
         // and message
         BinderValidationStatus<Person> status2 = binder.validate();
         BinderValidationStatus<?> status = statusCapture.get();
-        Assert.assertSame(status2, status);
+        assertSame(status2, status);
 
-        Assert.assertNull(nameField.getComponentError());
+        assertNull(nameField.getComponentError());
 
         List<BindingValidationStatus<?>> bindingStatuses = status
                 .getFieldValidationStatuses();
-        Assert.assertNotNull(bindingStatuses);
-        Assert.assertEquals(1, status.getFieldValidationErrors().size());
-        Assert.assertEquals(2, bindingStatuses.size());
+        assertNotNull(bindingStatuses);
+        assertEquals(1, status.getFieldValidationErrors().size());
+        assertEquals(2, bindingStatuses.size());
 
         BindingValidationStatus<?> r = bindingStatuses.get(0);
-        Assert.assertTrue(r.isError());
-        Assert.assertEquals(EMPTY_ERROR_MESSAGE, r.getMessage().get());
-        Assert.assertEquals(nameField, r.getField());
+        assertTrue(r.isError());
+        assertEquals(EMPTY_ERROR_MESSAGE, r.getMessage().get());
+        assertEquals(nameField, r.getField());
 
         r = bindingStatuses.get(1);
-        Assert.assertFalse(r.isError());
-        Assert.assertFalse(r.getMessage().isPresent());
-        Assert.assertEquals(ageField, r.getField());
+        assertFalse(r.isError());
+        assertFalse(r.getMessage().isPresent());
+        assertEquals(ageField, r.getField());
 
-        Assert.assertEquals(0, status.getBeanValidationResults().size());
-        Assert.assertEquals(0, status.getBeanValidationErrors().size());
+        assertEquals(0, status.getBeanValidationResults().size());
+        assertEquals(0, status.getBeanValidationErrors().size());
 
         nameField.setValue("foo");
         ageField.setValue("");
@@ -264,21 +269,21 @@ public class BinderValidationStatusTest
 
         status = statusCapture.get();
         bindingStatuses = status.getFieldValidationStatuses();
-        Assert.assertEquals(1, status.getFieldValidationErrors().size());
-        Assert.assertEquals(2, bindingStatuses.size());
+        assertEquals(1, status.getFieldValidationErrors().size());
+        assertEquals(2, bindingStatuses.size());
 
         r = bindingStatuses.get(0);
-        Assert.assertFalse(r.isError());
-        Assert.assertFalse(r.getMessage().isPresent());
-        Assert.assertEquals(nameField, r.getField());
+        assertFalse(r.isError());
+        assertFalse(r.getMessage().isPresent());
+        assertEquals(nameField, r.getField());
 
         r = bindingStatuses.get(1);
-        Assert.assertTrue(r.isError());
-        Assert.assertEquals("Value must be a number", r.getMessage().get());
-        Assert.assertEquals(ageField, r.getField());
+        assertTrue(r.isError());
+        assertEquals("Value must be a number", r.getMessage().get());
+        assertEquals(ageField, r.getField());
 
-        Assert.assertEquals(0, status.getBeanValidationResults().size());
-        Assert.assertEquals(0, status.getBeanValidationErrors().size());
+        assertEquals(0, status.getBeanValidationResults().size());
+        assertEquals(0, status.getBeanValidationErrors().size());
 
         statusCapture.set(null);
         // binding validations pass, binder validation fails
@@ -287,11 +292,11 @@ public class BinderValidationStatusTest
 
         status = statusCapture.get();
         bindingStatuses = status.getFieldValidationStatuses();
-        Assert.assertEquals(0, status.getFieldValidationErrors().size());
-        Assert.assertEquals(2, bindingStatuses.size());
+        assertEquals(0, status.getFieldValidationErrors().size());
+        assertEquals(2, bindingStatuses.size());
 
-        Assert.assertEquals(0, status.getBeanValidationResults().size());
-        Assert.assertEquals(0, status.getBeanValidationErrors().size());
+        assertEquals(0, status.getBeanValidationResults().size());
+        assertEquals(0, status.getBeanValidationErrors().size());
     }
 
     @Test
@@ -299,13 +304,11 @@ public class BinderValidationStatusTest
         AtomicReference<BinderValidationStatus<?>> statusCapture = new AtomicReference<>();
         binder.forField(nameField).withValidator(notEmpty)
                 .withValidationStatusHandler(evt -> {
-                    Assert.fail(
-                            "Using a custom status change handler so no change should end up here");
+                    fail("Using a custom status change handler so no change should end up here");
                 }).bind(Person::getFirstName, Person::setFirstName);
         binder.forField(ageField).withConverter(stringToInteger)
                 .withValidator(notNegative).withValidationStatusHandler(evt -> {
-                    Assert.fail(
-                            "Using a custom status change handler so no change should end up here");
+                    fail("Using a custom status change handler so no change should end up here");
                 }).bind(Person::getAge, Person::setAge);
         binder.withValidator(
                 bean -> !bean.getFirstName().isEmpty() && bean.getAge() > 0,
@@ -315,7 +318,7 @@ public class BinderValidationStatusTest
             statusCapture.set(r);
         });
         binder.setBean(item);
-        Assert.assertNull(nameField.getComponentError());
+        assertNull(nameField.getComponentError());
 
         nameField.setValue("");
         ageField.setValue("5");
@@ -324,28 +327,28 @@ public class BinderValidationStatusTest
         // and message
         BinderValidationStatus<Person> status2 = binder.validate();
         BinderValidationStatus<?> status = statusCapture.get();
-        Assert.assertSame(status2, status);
+        assertSame(status2, status);
 
-        Assert.assertNull(nameField.getComponentError());
+        assertNull(nameField.getComponentError());
 
         List<BindingValidationStatus<?>> bindingStatuses = status
                 .getFieldValidationStatuses();
-        Assert.assertNotNull(bindingStatuses);
-        Assert.assertEquals(1, status.getFieldValidationErrors().size());
-        Assert.assertEquals(2, bindingStatuses.size());
+        assertNotNull(bindingStatuses);
+        assertEquals(1, status.getFieldValidationErrors().size());
+        assertEquals(2, bindingStatuses.size());
 
         BindingValidationStatus<?> r = bindingStatuses.get(0);
-        Assert.assertTrue(r.isError());
-        Assert.assertEquals(EMPTY_ERROR_MESSAGE, r.getMessage().get());
-        Assert.assertEquals(nameField, r.getField());
+        assertTrue(r.isError());
+        assertEquals(EMPTY_ERROR_MESSAGE, r.getMessage().get());
+        assertEquals(nameField, r.getField());
 
         r = bindingStatuses.get(1);
-        Assert.assertFalse(r.isError());
-        Assert.assertFalse(r.getMessage().isPresent());
-        Assert.assertEquals(ageField, r.getField());
+        assertFalse(r.isError());
+        assertFalse(r.getMessage().isPresent());
+        assertEquals(ageField, r.getField());
 
-        Assert.assertEquals(0, status.getBeanValidationResults().size());
-        Assert.assertEquals(0, status.getBeanValidationErrors().size());
+        assertEquals(0, status.getBeanValidationResults().size());
+        assertEquals(0, status.getBeanValidationErrors().size());
 
         nameField.setValue("foo");
         ageField.setValue("");
@@ -357,21 +360,21 @@ public class BinderValidationStatusTest
 
         status = statusCapture.get();
         bindingStatuses = status.getFieldValidationStatuses();
-        Assert.assertEquals(1, status.getFieldValidationErrors().size());
-        Assert.assertEquals(2, bindingStatuses.size());
+        assertEquals(1, status.getFieldValidationErrors().size());
+        assertEquals(2, bindingStatuses.size());
 
         r = bindingStatuses.get(0);
-        Assert.assertFalse(r.isError());
-        Assert.assertFalse(r.getMessage().isPresent());
-        Assert.assertEquals(nameField, r.getField());
+        assertFalse(r.isError());
+        assertFalse(r.getMessage().isPresent());
+        assertEquals(nameField, r.getField());
 
         r = bindingStatuses.get(1);
-        Assert.assertTrue(r.isError());
-        Assert.assertEquals("Value must be a number", r.getMessage().get());
-        Assert.assertEquals(ageField, r.getField());
+        assertTrue(r.isError());
+        assertEquals("Value must be a number", r.getMessage().get());
+        assertEquals(ageField, r.getField());
 
-        Assert.assertEquals(0, status.getBeanValidationResults().size());
-        Assert.assertEquals(0, status.getBeanValidationErrors().size());
+        assertEquals(0, status.getBeanValidationResults().size());
+        assertEquals(0, status.getBeanValidationErrors().size());
 
         statusCapture.set(null);
         // binding validations pass, binder validation fails
@@ -380,13 +383,13 @@ public class BinderValidationStatusTest
 
         status = statusCapture.get();
         bindingStatuses = status.getFieldValidationStatuses();
-        Assert.assertEquals(0, status.getFieldValidationErrors().size());
-        Assert.assertEquals(2, bindingStatuses.size());
+        assertEquals(0, status.getFieldValidationErrors().size());
+        assertEquals(2, bindingStatuses.size());
 
-        Assert.assertEquals(1, status.getBeanValidationResults().size());
-        Assert.assertEquals(1, status.getBeanValidationErrors().size());
+        assertEquals(1, status.getBeanValidationResults().size());
+        assertEquals(1, status.getBeanValidationErrors().size());
 
-        Assert.assertEquals("Need first name and age",
+        assertEquals("Need first name and age",
                 status.getBeanValidationErrors().get(0).getErrorMessage());
     }
 
@@ -396,7 +399,7 @@ public class BinderValidationStatusTest
                 .withValidator(notEmpty).withValidationStatusHandler(evt -> {
                 }).bind(Person::getFirstName, Person::setFirstName);
 
-        Assert.assertNull(nameField.getComponentError());
+        assertNull(nameField.getComponentError());
 
         nameField.setValue("");
 
@@ -405,7 +408,7 @@ public class BinderValidationStatusTest
         binding.validate();
 
         // no component error since default handler is replaced
-        Assert.assertNull(nameField.getComponentError());
+        assertNull(nameField.getComponentError());
     }
 
     @Test
@@ -416,7 +419,7 @@ public class BinderValidationStatusTest
                 .withValidator(notEmpty).withStatusLabel(label)
                 .bind(Person::getFirstName, Person::setFirstName);
 
-        Assert.assertNull(nameField.getComponentError());
+        assertNull(nameField.getComponentError());
 
         nameField.setValue("");
 
@@ -425,7 +428,7 @@ public class BinderValidationStatusTest
         binding.validate();
 
         // default behavior should update component error for the nameField
-        Assert.assertNull(nameField.getComponentError());
+        assertNull(nameField.getComponentError());
     }
 
     @Test(expected = IllegalStateException.class)
@@ -434,7 +437,7 @@ public class BinderValidationStatusTest
                 .withValidator(notEmpty);
         binding.bind(Person::getFirstName, Person::setFirstName);
 
-        binding.withValidationStatusHandler(evt -> Assert.fail());
+        binding.withValidationStatusHandler(evt -> fail());
     }
 
     @Test(expected = IllegalStateException.class)
@@ -487,7 +490,7 @@ public class BinderValidationStatusTest
         binding.bind(Person::getFirstName, Person::setFirstName);
 
         binder.setValidationStatusHandler(results -> {
-            Assert.fail();
+            fail();
         });
 
         binder.setValidationStatusHandler(results -> {
@@ -499,8 +502,8 @@ public class BinderValidationStatusTest
 
         List<BindingValidationStatus<?>> results = capture.get()
                 .getFieldValidationStatuses();
-        Assert.assertNotNull(results);
-        Assert.assertEquals(1, results.size());
-        Assert.assertFalse(results.get(0).isError());
+        assertNotNull(results);
+        assertEquals(1, results.size());
+        assertFalse(results.get(0).isError());
     }
 }
diff --git a/server/src/test/java/com/vaadin/data/BinderValueChangeTest.java b/server/src/test/java/com/vaadin/data/BinderValueChangeTest.java
index 985d0cc650..fbe1ee1d1f 100644
--- a/server/src/test/java/com/vaadin/data/BinderValueChangeTest.java
+++ b/server/src/test/java/com/vaadin/data/BinderValueChangeTest.java
@@ -15,9 +15,12 @@
  */
 package com.vaadin.data;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
 import java.util.concurrent.atomic.AtomicReference;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -57,32 +60,32 @@ public class BinderValueChangeTest
         BindingBuilder<Person, String> binding = binder.forField(nameField);
 
         nameField.setValue("");
-        Assert.assertNull(event.get());
+        assertNull(event.get());
 
         binding.bind(Person::getFirstName, Person::setFirstName);
-        Assert.assertNull(event.get());
+        assertNull(event.get());
     }
 
     @Test
     public void setBean_unbound_noEvents() {
         binder.addValueChangeListener(this::statusChanged);
 
-        Assert.assertNull(event.get());
+        assertNull(event.get());
 
         binder.setBean(item);
 
-        Assert.assertNull(event.get());
+        assertNull(event.get());
     }
 
     @Test
     public void readBean_unbound_noEvents() {
         binder.addValueChangeListener(this::statusChanged);
 
-        Assert.assertNull(event.get());
+        assertNull(event.get());
 
         binder.readBean(item);
 
-        Assert.assertNull(event.get());
+        assertNull(event.get());
     }
 
     @Test
@@ -95,7 +98,7 @@ public class BinderValueChangeTest
 
         binder.addValueChangeListener(this::statusChanged);
 
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         nameField.setValue("foo");
         verifyEvent(nameField);
     }
@@ -111,7 +114,7 @@ public class BinderValueChangeTest
 
         binder.addValueChangeListener(this::statusChanged);
 
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         nameField.setValue("foo");
         verifyEvent(nameField);
     }
@@ -127,7 +130,7 @@ public class BinderValueChangeTest
 
         binder.addValueChangeListener(this::statusChanged);
 
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         field.setValue("foo", true);
         verifyEvent(field, true);
     }
@@ -143,7 +146,7 @@ public class BinderValueChangeTest
                 .bind(Person::getAge, Person::setAge);
         binder.setBean(item);
 
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         ageField.setValue(String.valueOf(1));
         verifyEvent(ageField);
     }
@@ -154,14 +157,14 @@ public class BinderValueChangeTest
 
     private void verifyEvent(HasValue<?> field, boolean isUserOriginated) {
         ValueChangeEvent<?> changeEvent = event.get();
-        Assert.assertNotNull(changeEvent);
-        Assert.assertEquals(field, changeEvent.getSource());
-        Assert.assertEquals(field, changeEvent.getComponent());
-        Assert.assertEquals(isUserOriginated, changeEvent.isUserOriginated());
+        assertNotNull(changeEvent);
+        assertEquals(field, changeEvent.getSource());
+        assertEquals(field, changeEvent.getComponent());
+        assertEquals(isUserOriginated, changeEvent.isUserOriginated());
     }
 
     private void statusChanged(ValueChangeEvent<?> evt) {
-        Assert.assertNull(event.get());
+        assertNull(event.get());
         event.set(evt);
     }
 }
diff --git a/server/src/test/java/com/vaadin/data/HasValueTest.java b/server/src/test/java/com/vaadin/data/HasValueTest.java
index 5f255454c9..5b3a996740 100644
--- a/server/src/test/java/com/vaadin/data/HasValueTest.java
+++ b/server/src/test/java/com/vaadin/data/HasValueTest.java
@@ -15,9 +15,11 @@
  */
 package com.vaadin.data;
 
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertSame;
+
 import java.time.LocalDate;
 
-import org.junit.Assert;
 import org.junit.Test;
 import org.mockito.Mockito;
 
@@ -58,14 +60,13 @@ public class HasValueTest {
         assert nullable.isEmpty();
         assert nullable.getValue() == null;
 
-        Assert.assertFalse(nullable.getOptionalValue().isPresent());
+        assertFalse(nullable.getOptionalValue().isPresent());
 
         nullable.setValue(LocalDate.now());
 
         assert !nullable.isEmpty();
 
-        Assert.assertSame(nullable.getValue(),
-                nullable.getOptionalValue().get());
+        assertSame(nullable.getValue(), nullable.getOptionalValue().get());
     }
 
     @Test
@@ -77,13 +78,13 @@ public class HasValueTest {
         assert nonNullable.isEmpty();
         assert nonNullable.getValue() != null;
 
-        Assert.assertFalse(nonNullable.getOptionalValue().isPresent());
+        assertFalse(nonNullable.getOptionalValue().isPresent());
 
         nonNullable.setValue("foo");
 
         assert !nonNullable.isEmpty();
 
-        Assert.assertSame(nonNullable.getValue(),
+        assertSame(nonNullable.getValue(),
                 nonNullable.getOptionalValue().get());
     }
 }
diff --git a/server/src/test/java/com/vaadin/data/Jsr303Test.java b/server/src/test/java/com/vaadin/data/Jsr303Test.java
index c907bd2af0..7463e0198a 100644
--- a/server/src/test/java/com/vaadin/data/Jsr303Test.java
+++ b/server/src/test/java/com/vaadin/data/Jsr303Test.java
@@ -16,6 +16,8 @@
 package com.vaadin.data;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.fail;
 
 import java.io.IOException;
 import java.io.InputStream;
@@ -26,7 +28,6 @@ import java.net.URLClassLoader;
 import javax.validation.Validation;
 
 import org.apache.commons.io.IOUtils;
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.data.util.BeanUtil;
@@ -82,7 +83,7 @@ public class Jsr303Test {
 
         @Override
         public void execute() {
-            Assert.assertFalse(BeanUtil.checkBeanValidationAvailable());
+            assertFalse(BeanUtil.checkBeanValidationAvailable());
 
             Binder<BeanToValidate> binder = new Binder<>(BeanToValidate.class);
             BeanToValidate item = new BeanToValidate();
@@ -102,7 +103,7 @@ public class Jsr303Test {
             try {
                 BeanValidationBinder<BeanToValidate> beanValidationBinder = new BeanValidationBinder<>(
                         BeanToValidate.class);
-                Assert.fail();
+                fail();
             } catch (IllegalStateException ignore) {
                 // an exception has to be thrown
             }
diff --git a/server/src/test/java/com/vaadin/data/NotEmptyTest.java b/server/src/test/java/com/vaadin/data/NotEmptyTest.java
index 6b13825455..adda12f71d 100644
--- a/server/src/test/java/com/vaadin/data/NotEmptyTest.java
+++ b/server/src/test/java/com/vaadin/data/NotEmptyTest.java
@@ -15,6 +15,9 @@
  */
 package com.vaadin.data;
 
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
 import java.io.IOException;
 import java.io.InputStream;
 import java.lang.reflect.InvocationTargetException;
@@ -23,7 +26,6 @@ import java.net.URLClassLoader;
 
 import org.apache.commons.io.IOUtils;
 import org.hibernate.validator.constraints.NotEmpty;
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.tests.data.bean.BeanToValidate;
@@ -82,7 +84,7 @@ public class NotEmptyTest {
             try {
                 Class.forName(NOT_EMPTY);
                 // The NotEmpty class must not be in the classpath
-                Assert.fail();
+                fail();
             } catch (ClassNotFoundException e) {
             }
             BeanValidationBinder<BeanToValidate> binder = new BeanValidationBinder<>(
@@ -96,7 +98,7 @@ public class NotEmptyTest {
             binder.bind(nameField, "firstname");
             binder.setBean(item);
 
-            Assert.assertTrue(nameField.isRequiredIndicatorVisible());
+            assertTrue(nameField.isRequiredIndicatorVisible());
         }
 
     }
diff --git a/server/src/test/java/com/vaadin/data/ResultTest.java b/server/src/test/java/com/vaadin/data/ResultTest.java
index 8f594c1300..69c5a86c04 100644
--- a/server/src/test/java/com/vaadin/data/ResultTest.java
+++ b/server/src/test/java/com/vaadin/data/ResultTest.java
@@ -15,7 +15,11 @@
  */
 package com.vaadin.data;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
 import org.junit.Test;
 
 import com.vaadin.server.SerializableFunction;
@@ -30,28 +34,28 @@ public class ResultTest {
     public void testOk() {
         String value = "foo";
         Result<String> ok = Result.ok(value);
-        Assert.assertFalse(ok.isError());
-        Assert.assertFalse(ok.getMessage().isPresent());
-        ok.ifOk(v -> Assert.assertEquals(value, v));
-        ok.ifError(msg -> Assert.fail());
+        assertFalse(ok.isError());
+        assertFalse(ok.getMessage().isPresent());
+        ok.ifOk(v -> assertEquals(value, v));
+        ok.ifError(msg -> fail());
     }
 
     @Test
     public void testError() {
         String message = "foo";
         Result<String> error = Result.error(message);
-        Assert.assertTrue(error.isError());
-        Assert.assertTrue(error.getMessage().isPresent());
-        error.ifOk(v -> Assert.fail());
-        error.ifError(msg -> Assert.assertEquals(message, msg));
-        Assert.assertEquals(message, error.getMessage().get());
+        assertTrue(error.isError());
+        assertTrue(error.getMessage().isPresent());
+        error.ifOk(v -> fail());
+        error.ifError(msg -> assertEquals(message, msg));
+        assertEquals(message, error.getMessage().get());
     }
 
     @Test
     public void of_noException() {
         Result<String> result = Result.of(() -> "", exception -> null);
-        Assert.assertTrue(result instanceof SimpleResult);
-        Assert.assertFalse(result.isError());
+        assertTrue(result instanceof SimpleResult);
+        assertFalse(result.isError());
     }
 
     @Test
@@ -60,9 +64,9 @@ public class ResultTest {
         Result<String> result = Result.of(() -> {
             throw new RuntimeException();
         }, exception -> message);
-        Assert.assertTrue(result instanceof SimpleResult);
-        Assert.assertTrue(result.isError());
-        Assert.assertEquals(message, result.getMessage().get());
+        assertTrue(result instanceof SimpleResult);
+        assertTrue(result.isError());
+        assertEquals(message, result.getMessage().get());
     }
 
     @SuppressWarnings("serial")
@@ -77,12 +81,12 @@ public class ResultTest {
             }
         };
         Result<String> mapResult = result.map(value -> {
-            Assert.assertEquals("foo", value);
+            assertEquals("foo", value);
             return "bar";
         });
-        Assert.assertTrue(mapResult instanceof SimpleResult);
-        Assert.assertFalse(mapResult.isError());
-        mapResult.ifOk(v -> Assert.assertEquals("bar", v));
+        assertTrue(mapResult instanceof SimpleResult);
+        assertFalse(mapResult.isError());
+        mapResult.ifOk(v -> assertEquals("bar", v));
     }
 
     @SuppressWarnings("serial")
@@ -97,11 +101,11 @@ public class ResultTest {
             }
         };
         Result<String> mapResult = result.map(value -> {
-            Assert.assertEquals("foo", value);
+            assertEquals("foo", value);
             return "somevalue";
         });
-        Assert.assertTrue(mapResult instanceof SimpleResult);
-        Assert.assertTrue(mapResult.isError());
-        mapResult.ifError(msg -> Assert.assertEquals("bar", msg));
+        assertTrue(mapResult instanceof SimpleResult);
+        assertTrue(mapResult.isError());
+        mapResult.ifError(msg -> assertEquals("bar", msg));
     }
 }
diff --git a/server/src/test/java/com/vaadin/data/ValidatorTest.java b/server/src/test/java/com/vaadin/data/ValidatorTest.java
index 75ac1fcf5a..7d29b6941e 100644
--- a/server/src/test/java/com/vaadin/data/ValidatorTest.java
+++ b/server/src/test/java/com/vaadin/data/ValidatorTest.java
@@ -15,10 +15,12 @@
  */
 package com.vaadin.data;
 
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import java.util.Locale;
 import java.util.Objects;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.data.validator.ValidatorTestBase;
@@ -33,7 +35,7 @@ public class ValidatorTest extends ValidatorTestBase {
     public void alwaysPass() {
         Validator<String> alwaysPass = Validator.alwaysPass();
         ValidationResult result = alwaysPass.apply("foo", new ValueContext());
-        Assert.assertFalse(result.isError());
+        assertFalse(result.isError());
     }
 
     @Test
@@ -41,10 +43,10 @@ public class ValidatorTest extends ValidatorTestBase {
         Validator<String> validator = Validator.from(Objects::nonNull,
                 "Cannot be null");
         ValidationResult result = validator.apply(null, new ValueContext());
-        Assert.assertTrue(result.isError());
+        assertTrue(result.isError());
 
         result = validator.apply("", new ValueContext());
-        Assert.assertFalse(result.isError());
+        assertFalse(result.isError());
     }
 
     @Test
diff --git a/server/src/test/java/com/vaadin/data/ValueContextTest.java b/server/src/test/java/com/vaadin/data/ValueContextTest.java
index b96f7463cb..9dd0e90b69 100644
--- a/server/src/test/java/com/vaadin/data/ValueContextTest.java
+++ b/server/src/test/java/com/vaadin/data/ValueContextTest.java
@@ -1,14 +1,15 @@
 package com.vaadin.data;
 
+import static org.junit.Assert.assertEquals;
+
 import java.util.Locale;
 import java.util.Objects;
 
-import com.vaadin.ui.CheckBox;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
 import com.vaadin.server.VaadinRequest;
+import com.vaadin.ui.CheckBox;
 import com.vaadin.ui.TextField;
 import com.vaadin.ui.UI;
 
@@ -24,8 +25,8 @@ public class ValueContextTest extends UI {
         ValueContext fromComponent = new ValueContext(textField);
         Locale locale = fromComponent.getLocale().orElse(null);
         Objects.requireNonNull(locale);
-        Assert.assertEquals("Unexpected locale from component",
-                COMPONENT_LOCALE, locale);
+        assertEquals("Unexpected locale from component", COMPONENT_LOCALE,
+                locale);
     }
 
     @Test
@@ -33,8 +34,7 @@ public class ValueContextTest extends UI {
         ValueContext fromComponent = new ValueContext(textField);
         Locale locale = fromComponent.getLocale().orElse(null);
         Objects.requireNonNull(locale);
-        Assert.assertEquals("Unexpected locale from component", UI_LOCALE,
-                locale);
+        assertEquals("Unexpected locale from component", UI_LOCALE, locale);
     }
 
     @Test
@@ -43,30 +43,32 @@ public class ValueContextTest extends UI {
         ValueContext fromComponent = new ValueContext(textField);
         Locale locale = fromComponent.getLocale().orElse(null);
         Objects.requireNonNull(locale);
-        Assert.assertEquals("Unexpected locale from component",
-                Locale.getDefault(), locale);
+        assertEquals("Unexpected locale from component", Locale.getDefault(),
+                locale);
     }
 
     @Test
     public void testHasValue1() {
         setLocale(null);
         ValueContext fromComponent = new ValueContext(textField);
-        Assert.assertEquals(textField, fromComponent.getHasValue().get());
+        assertEquals(textField, fromComponent.getHasValue().get());
     }
 
     @Test
     public void testHasValue2() {
         setLocale(null);
-        ValueContext fromComponent = new ValueContext(new CheckBox(), textField);
-        Assert.assertEquals(textField, fromComponent.getHasValue().get());
+        ValueContext fromComponent = new ValueContext(new CheckBox(),
+                textField);
+        assertEquals(textField, fromComponent.getHasValue().get());
     }
 
     @Test
     public void testHasValue3() {
         setLocale(null);
-        ValueContext fromComponent = new ValueContext(new CheckBox(), textField, Locale.CANADA);
-        Assert.assertEquals(textField, fromComponent.getHasValue().get());
-        Assert.assertEquals(Locale.CANADA, fromComponent.getLocale().get());
+        ValueContext fromComponent = new ValueContext(new CheckBox(), textField,
+                Locale.CANADA);
+        assertEquals(textField, fromComponent.getHasValue().get());
+        assertEquals(Locale.CANADA, fromComponent.getLocale().get());
     }
 
     @Before
diff --git a/server/src/test/java/com/vaadin/data/provider/AbstractDataProviderTest.java b/server/src/test/java/com/vaadin/data/provider/AbstractDataProviderTest.java
index 3cd368944d..6e94d94b50 100644
--- a/server/src/test/java/com/vaadin/data/provider/AbstractDataProviderTest.java
+++ b/server/src/test/java/com/vaadin/data/provider/AbstractDataProviderTest.java
@@ -15,10 +15,13 @@
  */
 package com.vaadin.data.provider;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.stream.Stream;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.shared.Registration;
@@ -53,12 +56,12 @@ public class AbstractDataProviderTest {
         TestDataProvider dataProvider = new TestDataProvider();
         AtomicReference<DataChangeEvent<Object>> event = new AtomicReference<>();
         dataProvider.addDataProviderListener(ev -> {
-            Assert.assertNull(event.get());
+            assertNull(event.get());
             event.set(ev);
         });
         dataProvider.refreshAll();
-        Assert.assertNotNull(event.get());
-        Assert.assertEquals(dataProvider, event.get().getSource());
+        assertNotNull(event.get());
+        assertEquals(dataProvider, event.get().getSource());
     }
 
     @Test
@@ -69,6 +72,6 @@ public class AbstractDataProviderTest {
                 .addDataProviderListener(ev -> event.set(ev));
         registration.remove();
         dataProvider.refreshAll();
-        Assert.assertNull(event.get());
+        assertNull(event.get());
     }
 }
diff --git a/server/src/test/java/com/vaadin/data/provider/ConfigurableFilterDataProviderWrapperTest.java b/server/src/test/java/com/vaadin/data/provider/ConfigurableFilterDataProviderWrapperTest.java
index b2be27bd8d..5d31dcb150 100644
--- a/server/src/test/java/com/vaadin/data/provider/ConfigurableFilterDataProviderWrapperTest.java
+++ b/server/src/test/java/com/vaadin/data/provider/ConfigurableFilterDataProviderWrapperTest.java
@@ -15,7 +15,8 @@
  */
 package com.vaadin.data.provider;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+
 import org.junit.Test;
 
 import com.vaadin.data.provider.BackendDataProviderTest.StrBeanBackEndDataProvider;
@@ -48,12 +49,12 @@ public class ConfigurableFilterDataProviderWrapperTest {
     public void void_setFilter() {
         configurableVoid.setFilter(xyzFilter);
 
-        Assert.assertEquals("Set filter should be used", 1,
+        assertEquals("Set filter should be used", 1,
                 configurableVoid.size(new Query<>()));
 
         configurableVoid.setFilter(null);
 
-        Assert.assertEquals("null filter should return all items", 100,
+        assertEquals("null filter should return all items", 100,
                 configurableVoid.size(new Query<>()));
     }
 
@@ -68,21 +69,21 @@ public class ConfigurableFilterDataProviderWrapperTest {
     public void predicate_setFilter() {
         configurablePredicate.setFilter(Integer.valueOf(50));
 
-        Assert.assertEquals("Set filter should be used", 49,
+        assertEquals("Set filter should be used", 49,
                 configurablePredicate.size(new Query<>()));
 
         configurablePredicate.setFilter(null);
 
-        Assert.assertEquals("null filter should return all items", 100,
+        assertEquals("null filter should return all items", 100,
                 configurablePredicate.size(new Query<>()));
     }
 
     @Test
     public void predicate_queryFilter() {
-        Assert.assertEquals("Query filter should be used", 1,
+        assertEquals("Query filter should be used", 1,
                 configurablePredicate.size(new Query<>("Xyz")));
 
-        Assert.assertEquals("null query filter should return all items", 100,
+        assertEquals("null query filter should return all items", 100,
                 configurablePredicate.size(new Query<>()));
     }
 
@@ -90,12 +91,12 @@ public class ConfigurableFilterDataProviderWrapperTest {
     public void predicate_combinedFilters() {
         configurablePredicate.setFilter(Integer.valueOf(50));
 
-        Assert.assertEquals("Both filters should be used", 0,
+        assertEquals("Both filters should be used", 0,
                 configurablePredicate.size(new Query<>("Xyz")));
 
         configurablePredicate.setFilter(null);
 
-        Assert.assertEquals("Only zyz filter should be used", 1,
+        assertEquals("Only zyz filter should be used", 1,
                 configurablePredicate.size(new Query<>("Xyz")));
     }
 
diff --git a/server/src/test/java/com/vaadin/data/provider/DataCommunicatorTest.java b/server/src/test/java/com/vaadin/data/provider/DataCommunicatorTest.java
index 53913325a5..d3b4add32b 100644
--- a/server/src/test/java/com/vaadin/data/provider/DataCommunicatorTest.java
+++ b/server/src/test/java/com/vaadin/data/provider/DataCommunicatorTest.java
@@ -15,12 +15,13 @@
  */
 package com.vaadin.data.provider;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import java.util.Collections;
 import java.util.concurrent.Future;
 
-import elemental.json.Json;
-import elemental.json.JsonArray;
-import org.junit.Assert;
 import org.junit.Test;
 import org.mockito.Mockito;
 
@@ -31,10 +32,10 @@ import com.vaadin.server.VaadinSession;
 import com.vaadin.shared.Registration;
 import com.vaadin.ui.UI;
 
+import elemental.json.Json;
+import elemental.json.JsonArray;
 import elemental.json.JsonObject;
 
-import static org.junit.Assert.assertFalse;
-
 /**
  * @author Vaadin Ltd
  *
@@ -134,7 +135,7 @@ public class DataCommunicatorTest {
 
         communicator.extend(ui);
 
-        Assert.assertTrue(dataProvider.isListenerAdded());
+        assertTrue(dataProvider.isListenerAdded());
     }
 
     @Test
@@ -150,7 +151,7 @@ public class DataCommunicatorTest {
 
         communicator.extend(ui);
 
-        Assert.assertTrue(dataProvider.isListenerAdded());
+        assertTrue(dataProvider.isListenerAdded());
 
         communicator.detach();
 
@@ -174,25 +175,25 @@ public class DataCommunicatorTest {
 
         // Generate initial data.
         communicator.beforeClientResponse(true);
-        Assert.assertEquals("DataGenerator generate was not called",
-                TEST_OBJECT, generator.generated);
+        assertEquals("DataGenerator generate was not called", TEST_OBJECT,
+                generator.generated);
         generator.generated = null;
 
         // Make sure data does not get re-generated
         communicator.beforeClientResponse(false);
-        Assert.assertEquals("DataGenerator generate was called again", null,
+        assertEquals("DataGenerator generate was called again", null,
                 generator.generated);
 
         // Refresh a data object to trigger an update.
         dataProvider.refreshItem(TEST_OBJECT);
 
-        Assert.assertEquals("DataGenerator refresh was not called", TEST_OBJECT,
+        assertEquals("DataGenerator refresh was not called", TEST_OBJECT,
                 generator.refreshed);
 
         // Test refreshed data generation
         communicator.beforeClientResponse(false);
-        Assert.assertEquals("DataGenerator generate was not called",
-                TEST_OBJECT, generator.generated);
+        assertEquals("DataGenerator generate was not called", TEST_OBJECT,
+                generator.generated);
     }
 
     @Test
@@ -213,7 +214,8 @@ public class DataCommunicatorTest {
         keys.set(0, key);
         communicator.onDropRows(keys);
         // Replace everything
-        communicator.setDataProvider(new ListDataProvider<>(Collections.singleton(new Object())));
+        communicator.setDataProvider(
+                new ListDataProvider<>(Collections.singleton(new Object())));
         // The communicator does not have to throw exceptions during
         // request finalization
         communicator.beforeClientResponse(false);
diff --git a/server/src/test/java/com/vaadin/data/provider/DataProviderTestBase.java b/server/src/test/java/com/vaadin/data/provider/DataProviderTestBase.java
index 2fea57ae80..20513674d9 100644
--- a/server/src/test/java/com/vaadin/data/provider/DataProviderTestBase.java
+++ b/server/src/test/java/com/vaadin/data/provider/DataProviderTestBase.java
@@ -1,5 +1,7 @@
 package com.vaadin.data.provider;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertTrue;
 
 import java.util.Comparator;
@@ -7,7 +9,6 @@ import java.util.LinkedList;
 import java.util.List;
 import java.util.stream.Collectors;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -87,16 +88,15 @@ public abstract class DataProviderTestBase<D extends DataProvider<StrBean, Seria
                 .collect(Collectors.toList());
 
         // First value in data is { Xyz, 10, 100 } which should be last in list
-        Assert.assertNotEquals("First value should not match", data.get(0),
+        assertNotEquals("First value should not match", data.get(0),
                 list.get(0));
 
-        Assert.assertEquals("Sorted data and original data sizes don't match",
+        assertEquals("Sorted data and original data sizes don't match",
                 data.size(), list.size());
 
         data.sort(comp);
         for (int i = 0; i < data.size(); ++i) {
-            Assert.assertEquals("Sorting result differed", data.get(i),
-                    list.get(i));
+            assertEquals("Sorting result differed", data.get(i), list.get(i));
         }
     }
 
@@ -111,24 +111,23 @@ public abstract class DataProviderTestBase<D extends DataProvider<StrBean, Seria
                         Comparator.comparing(StrBean::getRandomNumber)))
                 .collect(Collectors.toList());
 
-        Assert.assertEquals("Sorted data and original data sizes don't match",
+        assertEquals("Sorted data and original data sizes don't match",
                 data.size(), list.size());
 
         for (int i = 1; i < list.size(); ++i) {
             StrBean prev = list.get(i - 1);
             StrBean cur = list.get(i);
             // Test specific sort
-            Assert.assertTrue(
+            assertTrue(
                     "Failure: " + prev.getRandomNumber() + " > "
                             + cur.getRandomNumber(),
                     prev.getRandomNumber() <= cur.getRandomNumber());
 
             if (prev.getRandomNumber() == cur.getRandomNumber()) {
                 // Test default sort
-                Assert.assertTrue(
-                        prev.getValue().compareTo(cur.getValue()) <= 0);
+                assertTrue(prev.getValue().compareTo(cur.getValue()) <= 0);
                 if (prev.getValue().equals(cur.getValue())) {
-                    Assert.assertTrue(prev.getId() > cur.getId());
+                    assertTrue(prev.getId() > cur.getId());
                 }
             }
         }
@@ -142,7 +141,7 @@ public abstract class DataProviderTestBase<D extends DataProvider<StrBean, Seria
         List<StrBean> list = dataProvider.fetch(new Query<>())
                 .collect(Collectors.toList());
 
-        Assert.assertEquals("Sorted data and original data sizes don't match",
+        assertEquals("Sorted data and original data sizes don't match",
                 data.size(), list.size());
 
         for (int i = 1; i < list.size(); ++i) {
@@ -150,7 +149,7 @@ public abstract class DataProviderTestBase<D extends DataProvider<StrBean, Seria
             StrBean cur = list.get(i);
 
             // Test default sort
-            Assert.assertTrue(prev.getValue().compareTo(cur.getValue()) <= 0);
+            assertTrue(prev.getValue().compareTo(cur.getValue()) <= 0);
         }
     }
 
@@ -159,25 +158,24 @@ public abstract class DataProviderTestBase<D extends DataProvider<StrBean, Seria
         DataProvider<StrBean, String> strFilterDataProvider = dataProvider
                 .withConvertedFilter(
                         text -> strBean -> strBean.getValue().contains(text));
-        Assert.assertEquals("Only one item should match 'Xyz'", 1,
+        assertEquals("Only one item should match 'Xyz'", 1,
                 strFilterDataProvider.size(new Query<>("Xyz")));
-        Assert.assertEquals("No item should match 'Zyx'", 0,
+        assertEquals("No item should match 'Zyx'", 0,
                 strFilterDataProvider.size(new Query<>("Zyx")));
-        Assert.assertEquals("Unexpected number of matches for 'Foo'", 36,
+        assertEquals("Unexpected number of matches for 'Foo'", 36,
                 strFilterDataProvider.size(new Query<>("Foo")));
 
-        Assert.assertEquals("No items should've been filtered out", data.size(),
+        assertEquals("No items should've been filtered out", data.size(),
                 strFilterDataProvider.size(new Query<>()));
     }
 
     @Test
     public void filteringListDataProvider_defaultFilterType() {
-        Assert.assertEquals("Only one item should match 'Xyz'", 1,
-                dataProvider.size(new Query<>(
-                        strBean -> strBean.getValue().contains("Xyz"))));
-        Assert.assertEquals("No item should match 'Zyx'", 0, dataProvider.size(
+        assertEquals("Only one item should match 'Xyz'", 1, dataProvider.size(
+                new Query<>(strBean -> strBean.getValue().contains("Xyz"))));
+        assertEquals("No item should match 'Zyx'", 0, dataProvider.size(
                 new Query<>(strBean -> strBean.getValue().contains("Zyx"))));
-        Assert.assertEquals("Unexpected number of matches for 'Foo'", 36,
+        assertEquals("Unexpected number of matches for 'Foo'", 36,
                 dataProvider.size(new Query<>(fooFilter)));
     }
 
@@ -187,8 +185,7 @@ public abstract class DataProviderTestBase<D extends DataProvider<StrBean, Seria
 
     protected static <F> void assertSizeWithFilter(int expectedSize,
             DataProvider<?, F> dataProvider, F filterValue) {
-        Assert.assertEquals(expectedSize,
-                dataProvider.size(new Query<>(filterValue)));
+        assertEquals(expectedSize, dataProvider.size(new Query<>(filterValue)));
     }
 
 }
diff --git a/server/src/test/java/com/vaadin/data/provider/ListDataProviderTest.java b/server/src/test/java/com/vaadin/data/provider/ListDataProviderTest.java
index 1ffa444f50..8b1792689a 100644
--- a/server/src/test/java/com/vaadin/data/provider/ListDataProviderTest.java
+++ b/server/src/test/java/com/vaadin/data/provider/ListDataProviderTest.java
@@ -1,11 +1,14 @@
 package com.vaadin.data.provider;
 
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+
 import java.util.Comparator;
 import java.util.List;
 import java.util.Locale;
 import java.util.stream.Collectors;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.server.SerializableComparator;
@@ -28,7 +31,7 @@ public class ListDataProviderTest
         int[] threeFirstIds = dataProvider.fetch(new Query<>())
                 .mapToInt(StrBean::getId).limit(3).toArray();
 
-        Assert.assertArrayEquals(new int[] { 0, 1, 2 }, threeFirstIds);
+        assertArrayEquals(new int[] { 0, 1, 2 }, threeFirstIds);
     }
 
     @Test
@@ -40,7 +43,7 @@ public class ListDataProviderTest
         int[] threeFirstIds = dataProvider.fetch(new Query<>())
                 .mapToInt(StrBean::getId).limit(3).toArray();
 
-        Assert.assertArrayEquals(new int[] { 98, 97, 96 }, threeFirstIds);
+        assertArrayEquals(new int[] { 98, 97, 96 }, threeFirstIds);
     }
 
     @Test
@@ -54,54 +57,51 @@ public class ListDataProviderTest
                 .limit(3).collect(Collectors.toList());
 
         // First one is Xyz
-        Assert.assertEquals(new StrBean("Xyz", 10, 100),
-                threeFirstItems.get(0));
+        assertEquals(new StrBean("Xyz", 10, 100), threeFirstItems.get(0));
         // The following are Foos ordered by id
-        Assert.assertEquals(new StrBean("Foo", 93, 2), threeFirstItems.get(1));
-        Assert.assertEquals(new StrBean("Foo", 91, 2), threeFirstItems.get(2));
+        assertEquals(new StrBean("Foo", 93, 2), threeFirstItems.get(1));
+        assertEquals(new StrBean("Foo", 91, 2), threeFirstItems.get(2));
     }
 
     @Test
     public void setFilter() {
         dataProvider.setFilter(item -> item.getValue().equals("Foo"));
 
-        Assert.assertEquals(36, sizeWithUnfilteredQuery());
+        assertEquals(36, sizeWithUnfilteredQuery());
 
         dataProvider.setFilter(item -> !item.getValue().equals("Foo"));
 
-        Assert.assertEquals(
-                "Previous filter should be reset when setting a new one", 64,
-                sizeWithUnfilteredQuery());
+        assertEquals("Previous filter should be reset when setting a new one",
+                64, sizeWithUnfilteredQuery());
 
         dataProvider.setFilter(null);
 
-        Assert.assertEquals("Setting filter to null should remove all filters",
-                100, sizeWithUnfilteredQuery());
+        assertEquals("Setting filter to null should remove all filters", 100,
+                sizeWithUnfilteredQuery());
     }
 
     @Test
     public void setFilter_valueProvider() {
         dataProvider.setFilter(StrBean::getValue, "Foo"::equals);
 
-        Assert.assertEquals(36, sizeWithUnfilteredQuery());
+        assertEquals(36, sizeWithUnfilteredQuery());
 
         dataProvider.setFilter(StrBean::getValue,
                 value -> !value.equals("Foo"));
 
-        Assert.assertEquals(
-                "Previous filter should be reset when setting a new one", 64,
-                sizeWithUnfilteredQuery());
+        assertEquals("Previous filter should be reset when setting a new one",
+                64, sizeWithUnfilteredQuery());
     }
 
     @Test
     public void setFilterEquals() {
         dataProvider.setFilterByValue(StrBean::getValue, "Foo");
 
-        Assert.assertEquals(36, sizeWithUnfilteredQuery());
+        assertEquals(36, sizeWithUnfilteredQuery());
 
         dataProvider.setFilterByValue(StrBean::getValue, "Bar");
 
-        Assert.assertEquals(23, sizeWithUnfilteredQuery());
+        assertEquals(23, sizeWithUnfilteredQuery());
     }
 
     @Test
@@ -110,7 +110,7 @@ public class ListDataProviderTest
 
         dataProvider.addFilter(item -> item.getId() > 50);
 
-        Assert.assertEquals("Both filters should be used", 17,
+        assertEquals("Both filters should be used", 17,
                 sizeWithUnfilteredQuery());
     }
 
@@ -118,7 +118,7 @@ public class ListDataProviderTest
     public void addFilter_noPreviousFilter() {
         dataProvider.addFilter(item -> item.getId() > 50);
 
-        Assert.assertEquals(48, sizeWithUnfilteredQuery());
+        assertEquals(48, sizeWithUnfilteredQuery());
     }
 
     @Test
@@ -127,7 +127,7 @@ public class ListDataProviderTest
 
         dataProvider.addFilter(StrBean::getValue, "Foo"::equals);
 
-        Assert.assertEquals("Both filters should be used", 17,
+        assertEquals("Both filters should be used", 17,
                 sizeWithUnfilteredQuery());
     }
 
@@ -137,7 +137,7 @@ public class ListDataProviderTest
 
         dataProvider.addFilterByValue(StrBean::getValue, "Foo");
 
-        Assert.assertEquals("Both filters should be used", 17,
+        assertEquals("Both filters should be used", 17,
                 sizeWithUnfilteredQuery());
     }
 
@@ -145,11 +145,11 @@ public class ListDataProviderTest
     public void addFilter_firstAddedUsedFirst() {
         dataProvider.addFilter(item -> false);
         dataProvider.addFilter(item -> {
-            Assert.fail("This filter should never be invoked");
+            fail("This filter should never be invoked");
             return true;
         });
 
-        Assert.assertEquals(0, sizeWithUnfilteredQuery());
+        assertEquals(0, sizeWithUnfilteredQuery());
     }
 
     @Test
@@ -158,7 +158,7 @@ public class ListDataProviderTest
 
         int size = dataProvider.size(new Query<>(item -> item.getId() > 50));
 
-        Assert.assertEquals("Both filters should be used", 17, size);
+        assertEquals("Both filters should be used", 17, size);
     }
 
     @Test
@@ -166,11 +166,11 @@ public class ListDataProviderTest
         dataProvider.setFilter(item -> false);
 
         int size = dataProvider.size(new Query<>(item -> {
-            Assert.fail("This filter should never be invoked");
+            fail("This filter should never be invoked");
             return true;
         }));
 
-        Assert.assertEquals(0, size);
+        assertEquals(0, size);
     }
 
     @Test
diff --git a/server/src/test/java/com/vaadin/data/provider/ReplaceListDataProviderTest.java b/server/src/test/java/com/vaadin/data/provider/ReplaceListDataProviderTest.java
index 5c7448d17e..d2181fdb34 100644
--- a/server/src/test/java/com/vaadin/data/provider/ReplaceListDataProviderTest.java
+++ b/server/src/test/java/com/vaadin/data/provider/ReplaceListDataProviderTest.java
@@ -1,9 +1,13 @@
 package com.vaadin.data.provider;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertTrue;
+
 import java.util.ArrayList;
 import java.util.Arrays;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 /**
@@ -21,13 +25,13 @@ public class ReplaceListDataProviderTest {
     public void testGetIdOfItem() {
         Object id = dataProvider.fetch(new Query<>()).findFirst()
                 .map(dataProvider::getId).get();
-        Assert.assertEquals("DataProvider not using correct identifier getter",
+        assertEquals("DataProvider not using correct identifier getter",
                 TEST_OBJECT.getId(), id);
     }
 
     @Test
     public void testGetIdOfReplacementItem() {
-        Assert.assertFalse("Test object was stale before making any changes.",
+        assertFalse("Test object was stale before making any changes.",
                 dataProvider.isStale(TEST_OBJECT));
 
         dataProvider.refreshItem(new StrBean("Replacement TestObject", 10, -2));
@@ -36,13 +40,13 @@ public class ReplaceListDataProviderTest {
                 .get();
         Object id = dataProvider.getId(fromDataProvider);
 
-        Assert.assertNotEquals("DataProvider did not return the replacement",
+        assertNotEquals("DataProvider did not return the replacement",
                 TEST_OBJECT, fromDataProvider);
 
-        Assert.assertEquals("DataProvider not using correct identifier getter",
+        assertEquals("DataProvider not using correct identifier getter",
                 TEST_OBJECT.getId(), id);
 
-        Assert.assertTrue("Old test object should be stale",
+        assertTrue("Old test object should be stale",
                 dataProvider.isStale(TEST_OBJECT));
     }
 }
diff --git a/server/src/test/java/com/vaadin/data/provider/SortOrderBuildersTest.java b/server/src/test/java/com/vaadin/data/provider/SortOrderBuildersTest.java
index e289686040..7939217969 100644
--- a/server/src/test/java/com/vaadin/data/provider/SortOrderBuildersTest.java
+++ b/server/src/test/java/com/vaadin/data/provider/SortOrderBuildersTest.java
@@ -1,10 +1,11 @@
 package com.vaadin.data.provider;
 
+import static org.junit.Assert.assertEquals;
+
 import java.time.LocalDate;
 import java.util.Arrays;
 import java.util.List;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.shared.data.sort.SortDirection;
@@ -55,12 +56,11 @@ public class SortOrderBuildersTest {
 
     private <T extends SortOrder<?>> void verifySortOrders(List<T> order1,
             List<T> order2) {
-        Assert.assertEquals(order1.size(), order2.size());
+        assertEquals(order1.size(), order2.size());
         for (int i = 0; i < order1.size(); i++) {
-            Assert.assertEquals(order1.get(i).getDirection(),
+            assertEquals(order1.get(i).getDirection(),
                     order2.get(i).getDirection());
-            Assert.assertEquals(order1.get(i).getSorted(),
-                    order1.get(i).getSorted());
+            assertEquals(order1.get(i).getSorted(), order1.get(i).getSorted());
         }
     }
 }
diff --git a/server/src/test/java/com/vaadin/data/provider/TreeDataProviderTest.java b/server/src/test/java/com/vaadin/data/provider/TreeDataProviderTest.java
index 87b3ec0715..7d5f1c0909 100644
--- a/server/src/test/java/com/vaadin/data/provider/TreeDataProviderTest.java
+++ b/server/src/test/java/com/vaadin/data/provider/TreeDataProviderTest.java
@@ -1,5 +1,10 @@
 package com.vaadin.data.provider;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Comparator;
@@ -7,7 +12,6 @@ import java.util.List;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.data.TreeData;
@@ -64,78 +68,78 @@ public class TreeDataProviderTest
     @Test
     public void treeData_remove_root_item() {
         data.removeItem(null);
-        Assert.assertTrue(data.getChildren(null).isEmpty());
+        assertTrue(data.getChildren(null).isEmpty());
     }
 
     @Test
     public void treeData_clear() {
         data.clear();
-        Assert.assertTrue(data.getChildren(null).isEmpty());
+        assertTrue(data.getChildren(null).isEmpty());
     }
 
     @Test
     public void treeData_re_add_removed_item() {
         StrBean item = rootData.get(0);
         data.removeItem(item).addItem(null, item);
-        Assert.assertTrue(data.getChildren(null).contains(item));
+        assertTrue(data.getChildren(null).contains(item));
     }
 
     @Test
     public void treeData_get_parent() {
         StrBean root = rootData.get(0);
         StrBean firstChild = data.getChildren(root).get(0);
-        Assert.assertNull(data.getParent(root));
-        Assert.assertEquals(root, data.getParent(firstChild));
+        assertNull(data.getParent(root));
+        assertEquals(root, data.getParent(firstChild));
     }
 
     @Test
     public void treeData_set_parent() {
         StrBean item1 = rootData.get(0);
         StrBean item2 = rootData.get(1);
-        Assert.assertEquals(0, data.getChildren(item2).size());
-        Assert.assertEquals(10, data.getRootItems().size());
+        assertEquals(0, data.getChildren(item2).size());
+        assertEquals(10, data.getRootItems().size());
 
         // Move item1 as item2's child
         data.setParent(item1, item2);
-        Assert.assertEquals(1, data.getChildren(item2).size());
-        Assert.assertEquals(9, data.getRootItems().size());
-        Assert.assertEquals(item1, data.getChildren(item2).get(0));
+        assertEquals(1, data.getChildren(item2).size());
+        assertEquals(9, data.getRootItems().size());
+        assertEquals(item1, data.getChildren(item2).get(0));
 
         // Move back to root
         data.setParent(item1, null);
-        Assert.assertEquals(0, data.getChildren(item2).size());
-        Assert.assertEquals(10, data.getRootItems().size());
+        assertEquals(0, data.getChildren(item2).size());
+        assertEquals(10, data.getRootItems().size());
     }
 
     @Test
     public void treeData_move_after_sibling() {
         StrBean root0 = rootData.get(0);
         StrBean root9 = rootData.get(9);
-        Assert.assertEquals(root0, data.getRootItems().get(0));
-        Assert.assertEquals(root9, data.getRootItems().get(9));
+        assertEquals(root0, data.getRootItems().get(0));
+        assertEquals(root9, data.getRootItems().get(9));
 
         // Move to last position
         data.moveAfterSibling(root0, root9);
-        Assert.assertEquals(root0, data.getRootItems().get(9));
-        Assert.assertEquals(root9, data.getRootItems().get(8));
+        assertEquals(root0, data.getRootItems().get(9));
+        assertEquals(root9, data.getRootItems().get(8));
 
         // Move back to first position
         data.moveAfterSibling(root0, null);
-        Assert.assertEquals(root0, data.getRootItems().get(0));
-        Assert.assertEquals(root9, data.getRootItems().get(9));
+        assertEquals(root0, data.getRootItems().get(0));
+        assertEquals(root9, data.getRootItems().get(9));
 
         StrBean child0 = data.getChildren(root0).get(0);
         StrBean child2 = data.getChildren(root0).get(2);
 
         // Move first child to different position
         data.moveAfterSibling(child0, child2);
-        Assert.assertEquals(2, data.getChildren(root0).indexOf(child0));
-        Assert.assertEquals(1, data.getChildren(root0).indexOf(child2));
+        assertEquals(2, data.getChildren(root0).indexOf(child0));
+        assertEquals(1, data.getChildren(root0).indexOf(child2));
 
         // Move child back to first position
         data.moveAfterSibling(child0, null);
-        Assert.assertEquals(0, data.getChildren(root0).indexOf(child0));
-        Assert.assertEquals(2, data.getChildren(root0).indexOf(child2));
+        assertEquals(0, data.getChildren(root0).indexOf(child0));
+        assertEquals(2, data.getChildren(root0).indexOf(child2));
     }
 
     @Test(expected = IllegalArgumentException.class)
@@ -158,9 +162,9 @@ public class TreeDataProviderTest
         dataCollection.addRootItems(Arrays.asList("a", "b", "c"));
         dataStream.addRootItems(Arrays.asList("a", "b", "c").stream());
 
-        Assert.assertEquals(data.getRootItems(), dataVarargs.getRootItems());
-        Assert.assertEquals(data.getRootItems(), dataCollection.getRootItems());
-        Assert.assertEquals(data.getRootItems(), dataStream.getRootItems());
+        assertEquals(data.getRootItems(), dataVarargs.getRootItems());
+        assertEquals(data.getRootItems(), dataCollection.getRootItems());
+        assertEquals(data.getRootItems(), dataStream.getRootItems());
     }
 
     @Test
@@ -173,12 +177,12 @@ public class TreeDataProviderTest
             }
             return Arrays.asList(item + "/a", item + "/b", item + "/c");
         });
-        Assert.assertEquals(stringData.getChildren("a"),
+        assertEquals(stringData.getChildren("a"),
                 Arrays.asList("a/a", "a/b", "a/c"));
-        Assert.assertEquals(stringData.getChildren("b"),
+        assertEquals(stringData.getChildren("b"),
                 Arrays.asList("b/a", "b/b", "b/c"));
-        Assert.assertEquals(stringData.getChildren("c"), Arrays.asList());
-        Assert.assertEquals(stringData.getChildren("a/b"), Arrays.asList());
+        assertEquals(stringData.getChildren("c"), Arrays.asList());
+        assertEquals(stringData.getChildren("a/b"), Arrays.asList());
     }
 
     @Test
@@ -191,12 +195,12 @@ public class TreeDataProviderTest
             }
             return Stream.of(item + "/a", item + "/b", item + "/c");
         });
-        Assert.assertEquals(stringData.getChildren("a"),
+        assertEquals(stringData.getChildren("a"),
                 Arrays.asList("a/a", "a/b", "a/c"));
-        Assert.assertEquals(stringData.getChildren("b"),
+        assertEquals(stringData.getChildren("b"),
                 Arrays.asList("b/a", "b/b", "b/c"));
-        Assert.assertEquals(stringData.getChildren("c"), Arrays.asList());
-        Assert.assertEquals(stringData.getChildren("a/b"), Arrays.asList());
+        assertEquals(stringData.getChildren("c"), Arrays.asList());
+        assertEquals(stringData.getChildren("a/b"), Arrays.asList());
     }
 
     @Test
@@ -204,26 +208,26 @@ public class TreeDataProviderTest
         getDataProvider().setFilter(item -> item.getValue().equals("Xyz")
                 || item.getValue().equals("Baz"));
 
-        Assert.assertEquals(10, sizeWithUnfilteredQuery());
+        assertEquals(10, sizeWithUnfilteredQuery());
 
         getDataProvider().setFilter(item -> !item.getValue().equals("Foo")
                 && !item.getValue().equals("Xyz"));
 
-        Assert.assertEquals(
+        assertEquals(
                 "Previous filter should be replaced when setting a new one", 6,
                 sizeWithUnfilteredQuery());
 
         getDataProvider().setFilter(null);
 
-        Assert.assertEquals("Setting filter to null should remove all filters",
-                20, sizeWithUnfilteredQuery());
+        assertEquals("Setting filter to null should remove all filters", 20,
+                sizeWithUnfilteredQuery());
     }
 
     @Test
     public void addFilter() {
         getDataProvider().addFilter(item -> item.getId() <= 10);
         getDataProvider().addFilter(item -> item.getId() >= 5);
-        Assert.assertEquals(5, sizeWithUnfilteredQuery());
+        assertEquals(5, sizeWithUnfilteredQuery());
     }
 
     @Override
@@ -231,29 +235,28 @@ public class TreeDataProviderTest
         DataProvider<StrBean, String> strFilterDataProvider = getDataProvider()
                 .withConvertedFilter(
                         text -> strBean -> strBean.getValue().contains(text));
-        Assert.assertEquals("Only one item should match 'Xyz'", 1,
+        assertEquals("Only one item should match 'Xyz'", 1,
                 strFilterDataProvider
                         .size(new HierarchicalQuery<>("Xyz", null)));
-        Assert.assertEquals("No item should match 'Zyx'", 0,
-                strFilterDataProvider
-                        .size(new HierarchicalQuery<>("Zyx", null)));
-        Assert.assertEquals("Unexpected number of matches for 'Foo'", 3,
+        assertEquals("No item should match 'Zyx'", 0, strFilterDataProvider
+                .size(new HierarchicalQuery<>("Zyx", null)));
+        assertEquals("Unexpected number of matches for 'Foo'", 3,
                 strFilterDataProvider
                         .size(new HierarchicalQuery<>("Foo", null)));
-        Assert.assertEquals("No items should've been filtered out",
-                rootData.size(), strFilterDataProvider
+        assertEquals("No items should've been filtered out", rootData.size(),
+                strFilterDataProvider
                         .size(new HierarchicalQuery<>(null, null)));
     }
 
     @Override
     public void filteringListDataProvider_defaultFilterType() {
-        Assert.assertEquals("Only one item should match 'Xyz'", 1,
+        assertEquals("Only one item should match 'Xyz'", 1,
                 getDataProvider().size(new HierarchicalQuery<>(
                         strBean -> strBean.getValue().contains("Xyz"), null)));
-        Assert.assertEquals("No item should match 'Zyx'", 0,
+        assertEquals("No item should match 'Zyx'", 0,
                 dataProvider.size(new HierarchicalQuery<>(
                         strBean -> strBean.getValue().contains("Zyx"), null)));
-        Assert.assertEquals("Unexpected number of matches for 'Foo'", 3,
+        assertEquals("Unexpected number of matches for 'Foo'", 3,
                 getDataProvider()
                         .size(new HierarchicalQuery<>(fooFilter, null)));
     }
@@ -270,7 +273,7 @@ public class TreeDataProviderTest
                         null))
                 .collect(Collectors.toList());
 
-        Assert.assertEquals("Sorted data and original data sizes don't match",
+        assertEquals("Sorted data and original data sizes don't match",
                 getDataProvider().fetch(new HierarchicalQuery<>(null, null))
                         .count(),
                 list.size());
@@ -279,17 +282,16 @@ public class TreeDataProviderTest
             StrBean prev = list.get(i - 1);
             StrBean cur = list.get(i);
             // Test specific sort
-            Assert.assertTrue(
+            assertTrue(
                     "Failure: " + prev.getRandomNumber() + " > "
                             + cur.getRandomNumber(),
                     prev.getRandomNumber() <= cur.getRandomNumber());
 
             if (prev.getRandomNumber() == cur.getRandomNumber()) {
                 // Test default sort
-                Assert.assertTrue(
-                        prev.getValue().compareTo(cur.getValue()) <= 0);
+                assertTrue(prev.getValue().compareTo(cur.getValue()) <= 0);
                 if (prev.getValue().equals(cur.getValue())) {
-                    Assert.assertTrue(prev.getId() > cur.getId());
+                    assertTrue(prev.getId() > cur.getId());
                 }
             }
         }
@@ -304,7 +306,7 @@ public class TreeDataProviderTest
                 .fetch(new HierarchicalQuery<>(null, null))
                 .collect(Collectors.toList());
 
-        Assert.assertEquals("Sorted data and original data sizes don't match",
+        assertEquals("Sorted data and original data sizes don't match",
                 rootData.size(), list.size());
 
         for (int i = 1; i < list.size(); ++i) {
@@ -312,7 +314,7 @@ public class TreeDataProviderTest
             StrBean cur = list.get(i);
 
             // Test default sort
-            Assert.assertTrue(prev.getValue().compareTo(cur.getValue()) <= 0);
+            assertTrue(prev.getValue().compareTo(cur.getValue()) <= 0);
         }
     }
 
@@ -332,15 +334,15 @@ public class TreeDataProviderTest
                         .thenAsc("id").build(), comp, null, null))
                 .collect(Collectors.toList());
 
-        Assert.assertNotEquals("First value should not match", rootData.get(0),
+        assertNotEquals("First value should not match", rootData.get(0),
                 list.get(0));
 
-        Assert.assertEquals("Sorted data and original data sizes don't match",
+        assertEquals("Sorted data and original data sizes don't match",
                 rootData.size(), list.size());
 
         rootData.sort(comp);
         for (int i = 0; i < rootData.size(); ++i) {
-            Assert.assertEquals("Sorting result differed", rootData.get(i),
+            assertEquals("Sorting result differed", rootData.get(i),
                     list.get(i));
         }
     }
@@ -362,9 +364,8 @@ public class TreeDataProviderTest
     }
 
     private void assertHierarchyCorrect() {
-        Assert.assertEquals(flattenedData,
-                getFlattenedData(new ArrayList<>(), null));
-        Assert.assertEquals(flattenedData,
+        assertEquals(flattenedData, getFlattenedData(new ArrayList<>(), null));
+        assertEquals(flattenedData,
                 getFlattenedDataFromProvider(new ArrayList<>(), null));
     }
 
diff --git a/server/src/test/java/com/vaadin/data/provider/hierarchical/HierarchyMapperWithDataTest.java b/server/src/test/java/com/vaadin/data/provider/hierarchical/HierarchyMapperWithDataTest.java
index 4cfc8a8598..80d6a70cfd 100644
--- a/server/src/test/java/com/vaadin/data/provider/hierarchical/HierarchyMapperWithDataTest.java
+++ b/server/src/test/java/com/vaadin/data/provider/hierarchical/HierarchyMapperWithDataTest.java
@@ -1,5 +1,8 @@
 package com.vaadin.data.provider.hierarchical;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
 import java.util.ArrayList;
 import java.util.Comparator;
 import java.util.List;
@@ -7,7 +10,6 @@ import java.util.Objects;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.BeforeClass;
 import org.junit.Test;
@@ -50,58 +52,57 @@ public class HierarchyMapperWithDataTest {
 
     @Test
     public void expandRootNode() {
-        Assert.assertEquals("Map size should be equal to root node count",
-                ROOT_COUNT, mapper.getTreeSize());
+        assertEquals("Map size should be equal to root node count", ROOT_COUNT,
+                mapper.getTreeSize());
         expand(testData.get(0));
-        Assert.assertEquals("Should be root count + once parent count",
+        assertEquals("Should be root count + once parent count",
                 ROOT_COUNT + PARENT_COUNT, mapper.getTreeSize());
         checkMapSize();
     }
 
     @Test
     public void expandAndCollapseLastRootNode() {
-        Assert.assertEquals("Map size should be equal to root node count",
-                ROOT_COUNT, mapper.getTreeSize());
+        assertEquals("Map size should be equal to root node count", ROOT_COUNT,
+                mapper.getTreeSize());
         expand(roots.get(roots.size() - 1));
-        Assert.assertEquals("Should be root count + once parent count",
+        assertEquals("Should be root count + once parent count",
                 ROOT_COUNT + PARENT_COUNT, mapper.getTreeSize());
         checkMapSize();
         collapse(roots.get(roots.size() - 1));
-        Assert.assertEquals("Map size should be equal to root node count again",
+        assertEquals("Map size should be equal to root node count again",
                 ROOT_COUNT, mapper.getTreeSize());
         checkMapSize();
     }
 
     @Test
     public void expandHiddenNode() {
-        Assert.assertEquals("Map size should be equal to root node count",
-                ROOT_COUNT, mapper.getTreeSize());
+        assertEquals("Map size should be equal to root node count", ROOT_COUNT,
+                mapper.getTreeSize());
         expand(testData.get(1));
-        Assert.assertEquals(
-                "Map size should not change when expanding a hidden node",
+        assertEquals("Map size should not change when expanding a hidden node",
                 ROOT_COUNT, mapper.getTreeSize());
         checkMapSize();
         expand(roots.get(0));
-        Assert.assertEquals("Hidden node should now be expanded as well",
+        assertEquals("Hidden node should now be expanded as well",
                 ROOT_COUNT + PARENT_COUNT + LEAF_COUNT, mapper.getTreeSize());
         checkMapSize();
         collapse(roots.get(0));
-        Assert.assertEquals("Map size should be equal to root node count",
-                ROOT_COUNT, mapper.getTreeSize());
+        assertEquals("Map size should be equal to root node count", ROOT_COUNT,
+                mapper.getTreeSize());
         checkMapSize();
     }
 
     @Test
     public void expandLeafNode() {
-        Assert.assertEquals("Map size should be equal to root node count",
-                ROOT_COUNT, mapper.getTreeSize());
+        assertEquals("Map size should be equal to root node count", ROOT_COUNT,
+                mapper.getTreeSize());
         expand(testData.get(0));
         expand(testData.get(1));
-        Assert.assertEquals("Root and parent node expanded",
+        assertEquals("Root and parent node expanded",
                 ROOT_COUNT + PARENT_COUNT + LEAF_COUNT, mapper.getTreeSize());
         checkMapSize();
         expand(testData.get(2));
-        Assert.assertEquals("Expanding a leaf node should have no effect",
+        assertEquals("Expanding a leaf node should have no effect",
                 ROOT_COUNT + PARENT_COUNT + LEAF_COUNT, mapper.getTreeSize());
         checkMapSize();
     }
@@ -109,12 +110,12 @@ public class HierarchyMapperWithDataTest {
     @Test
     public void findParentIndexOfLeaf() {
         expand(testData.get(0));
-        Assert.assertEquals("Could not find the root node of a parent",
+        assertEquals("Could not find the root node of a parent",
                 Integer.valueOf(0), mapper.getParentIndex(testData.get(1)));
 
         expand(testData.get(1));
-        Assert.assertEquals("Could not find the parent of a leaf",
-                Integer.valueOf(1), mapper.getParentIndex(testData.get(2)));
+        assertEquals("Could not find the parent of a leaf", Integer.valueOf(1),
+                mapper.getParentIndex(testData.get(2)));
     }
 
     @Test
@@ -219,12 +220,13 @@ public class HierarchyMapperWithDataTest {
         List<Node> collect = mapper.fetchItems(range)
                 .collect(Collectors.toList());
         for (int i = 0; i < range.length(); ++i) {
-            Assert.assertEquals("Unexpected fetch results.",
+            assertEquals("Unexpected fetch results.",
                     expectedResult.get(i + range.getStart()), collect.get(i));
         }
     }
 
-    static List<Node> generateTestData(int rootCount, int parentCount, int leafCount) {
+    static List<Node> generateTestData(int rootCount, int parentCount,
+            int leafCount) {
         List<Node> nodes = new ArrayList<>();
         for (int i = 0; i < rootCount; ++i) {
             Node root = new Node();
@@ -241,20 +243,20 @@ public class HierarchyMapperWithDataTest {
     }
 
     private void checkMapSize() {
-        Assert.assertEquals("Map size not properly updated",
-                mapper.getTreeSize(), mapSize);
+        assertEquals("Map size not properly updated", mapper.getTreeSize(),
+                mapSize);
     }
 
     public void removeRows(Range range) {
-        Assert.assertTrue("Index not in range",
+        assertTrue("Index not in range",
                 0 <= range.getStart() && range.getStart() < mapSize);
-        Assert.assertTrue("Removing more items than in map",
+        assertTrue("Removing more items than in map",
                 range.getEnd() <= mapSize);
         mapSize -= range.length();
     }
 
     public void insertRows(Range range) {
-        Assert.assertTrue("Index not in range",
+        assertTrue("Index not in range",
                 0 <= range.getStart() && range.getStart() <= mapSize);
         mapSize += range.length();
     }
diff --git a/server/src/test/java/com/vaadin/data/provider/hierarchical/HierarchyMapperWithNumerousDataTest.java b/server/src/test/java/com/vaadin/data/provider/hierarchical/HierarchyMapperWithNumerousDataTest.java
index 611d15a2ac..6c0091f8bf 100644
--- a/server/src/test/java/com/vaadin/data/provider/hierarchical/HierarchyMapperWithNumerousDataTest.java
+++ b/server/src/test/java/com/vaadin/data/provider/hierarchical/HierarchyMapperWithNumerousDataTest.java
@@ -1,10 +1,12 @@
 package com.vaadin.data.provider.hierarchical;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
 import java.util.List;
 import java.util.Objects;
 import java.util.stream.Collectors;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.BeforeClass;
 import org.junit.Test;
@@ -29,7 +31,8 @@ public class HierarchyMapperWithNumerousDataTest {
 
     @BeforeClass
     public static void setupData() {
-        testData = HierarchyMapperWithDataTest.generateTestData(ROOT_COUNT, PARENT_COUNT, 0);
+        testData = HierarchyMapperWithDataTest.generateTestData(ROOT_COUNT,
+                PARENT_COUNT, 0);
         roots = testData.stream().filter(item -> item.getParent() == null)
                 .collect(Collectors.toList());
         data.addItems(roots,
@@ -45,16 +48,16 @@ public class HierarchyMapperWithNumerousDataTest {
     }
 
     /**
-     * Test for non-logarithmic {@code getParentOfItem} implementations
-     * 100000 entries and 1 second should be enought to make it run even
-     * on slow machines and weed out linear solutions
+     * Test for non-logarithmic {@code getParentOfItem} implementations 100000
+     * entries and 1 second should be enought to make it run even on slow
+     * machines and weed out linear solutions
      */
     @Test(timeout = 1000)
     public void expandRootNode() {
-        Assert.assertEquals("Map size should be equal to root node count",
-                ROOT_COUNT, mapper.getTreeSize());
+        assertEquals("Map size should be equal to root node count", ROOT_COUNT,
+                mapper.getTreeSize());
         expand(testData.get(0));
-        Assert.assertEquals("Should be root count + once parent count",
+        assertEquals("Should be root count + once parent count",
                 ROOT_COUNT + PARENT_COUNT, mapper.getTreeSize());
         checkMapSize();
     }
@@ -64,13 +67,13 @@ public class HierarchyMapperWithNumerousDataTest {
     }
 
     public void insertRows(Range range) {
-        Assert.assertTrue("Index not in range",
+        assertTrue("Index not in range",
                 0 <= range.getStart() && range.getStart() <= mapSize);
         mapSize += range.length();
     }
 
     private void checkMapSize() {
-        Assert.assertEquals("Map size not properly updated",
-                mapper.getTreeSize(), mapSize);
+        assertEquals("Map size not properly updated", mapper.getTreeSize(),
+                mapSize);
     }
 }
diff --git a/server/src/test/java/com/vaadin/data/validator/NotEmptyValidatorTest.java b/server/src/test/java/com/vaadin/data/validator/NotEmptyValidatorTest.java
index edd500a8a1..f238f67f11 100644
--- a/server/src/test/java/com/vaadin/data/validator/NotEmptyValidatorTest.java
+++ b/server/src/test/java/com/vaadin/data/validator/NotEmptyValidatorTest.java
@@ -15,7 +15,10 @@
  */
 package com.vaadin.data.validator;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import org.junit.Test;
 
 import com.vaadin.data.ValidationResult;
@@ -31,16 +34,16 @@ public class NotEmptyValidatorTest {
     public void nullValueIsDisallowed() {
         NotEmptyValidator<String> validator = new NotEmptyValidator<>("foo");
         ValidationResult result = validator.apply(null, new ValueContext());
-        Assert.assertTrue(result.isError());
-        Assert.assertEquals("foo", result.getErrorMessage());
+        assertTrue(result.isError());
+        assertEquals("foo", result.getErrorMessage());
     }
 
     @Test
     public void emptyValueIsDisallowed() {
         NotEmptyValidator<String> validator = new NotEmptyValidator<>("foo");
         ValidationResult result = validator.apply("", new ValueContext());
-        Assert.assertTrue(result.isError());
-        Assert.assertEquals("foo", result.getErrorMessage());
+        assertTrue(result.isError());
+        assertEquals("foo", result.getErrorMessage());
     }
 
     @Test
@@ -48,7 +51,7 @@ public class NotEmptyValidatorTest {
         NotEmptyValidator<Object> validator = new NotEmptyValidator<>("foo");
         Object value = new Object();
         ValidationResult result = validator.apply(value, new ValueContext());
-        Assert.assertFalse(result.isError());
-        Assert.assertFalse(result.isError());
+        assertFalse(result.isError());
+        assertFalse(result.isError());
     }
 }
diff --git a/server/src/test/java/com/vaadin/data/validator/ValidatorTestBase.java b/server/src/test/java/com/vaadin/data/validator/ValidatorTestBase.java
index a0bdd2964b..80ed1b26f1 100644
--- a/server/src/test/java/com/vaadin/data/validator/ValidatorTestBase.java
+++ b/server/src/test/java/com/vaadin/data/validator/ValidatorTestBase.java
@@ -1,8 +1,11 @@
 package com.vaadin.data.validator;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
 import java.util.Locale;
 
-import org.junit.Assert;
 import org.junit.Before;
 
 import com.vaadin.data.ValidationResult;
@@ -23,7 +26,7 @@ public class ValidatorTestBase {
     protected <T> void assertPasses(T value, Validator<? super T> validator) {
         ValidationResult result = validator.apply(value, new ValueContext());
         if (result.isError()) {
-            Assert.fail(value + " should pass " + validator + " but got "
+            fail(value + " should pass " + validator + " but got "
                     + result.getErrorMessage());
         }
     }
@@ -32,8 +35,8 @@ public class ValidatorTestBase {
             Validator<? super T> validator) {
         ValidationResult result = validator.apply(value,
                 new ValueContext(localeContext));
-        Assert.assertTrue(result.isError());
-        Assert.assertEquals(errorMessage, result.getErrorMessage());
+        assertTrue(result.isError());
+        assertEquals(errorMessage, result.getErrorMessage());
     }
 
     protected <T> void assertFails(T value, AbstractValidator<? super T> v) {
diff --git a/server/src/test/java/com/vaadin/event/selection/SelectionEventTest.java b/server/src/test/java/com/vaadin/event/selection/SelectionEventTest.java
index 5328ae9336..8418121c92 100644
--- a/server/src/test/java/com/vaadin/event/selection/SelectionEventTest.java
+++ b/server/src/test/java/com/vaadin/event/selection/SelectionEventTest.java
@@ -15,12 +15,14 @@
  */
 package com.vaadin.event.selection;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.LinkedHashSet;
 import java.util.Optional;
 
-import org.junit.Assert;
 import org.junit.Test;
 import org.mockito.Mockito;
 
@@ -42,10 +44,10 @@ public class SelectionEventTest {
         Optional<?> selected = event.getFirstSelectedItem();
 
         Mockito.verify(event).getValue();
-        Assert.assertEquals("foo", selected.get());
+        assertEquals("foo", selected.get());
 
         Mockito.when(event.getValue()).thenReturn(Collections.emptySet());
-        Assert.assertFalse(event.getFirstSelectedItem().isPresent());
+        assertFalse(event.getFirstSelectedItem().isPresent());
     }
 
     @SuppressWarnings({ "unchecked", "rawtypes" })
@@ -59,10 +61,10 @@ public class SelectionEventTest {
         Optional<?> selected = event.getSelectedItem();
 
         Mockito.verify(event).getSelectedItem();
-        Assert.assertEquals("foo", selected.get());
+        assertEquals("foo", selected.get());
 
         Mockito.when(event.getSelectedItem()).thenReturn(Optional.empty());
-        Assert.assertFalse(event.getFirstSelectedItem().isPresent());
+        assertFalse(event.getFirstSelectedItem().isPresent());
     }
 
 }
diff --git a/server/src/test/java/com/vaadin/server/AbstractClientConnectorProxyHandlingTest.java b/server/src/test/java/com/vaadin/server/AbstractClientConnectorProxyHandlingTest.java
index b3eb006e0d..e952c01340 100644
--- a/server/src/test/java/com/vaadin/server/AbstractClientConnectorProxyHandlingTest.java
+++ b/server/src/test/java/com/vaadin/server/AbstractClientConnectorProxyHandlingTest.java
@@ -15,10 +15,11 @@
  */
 package com.vaadin.server;
 
+import static org.junit.Assert.fail;
+
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 /**
@@ -38,13 +39,12 @@ public class AbstractClientConnectorProxyHandlingTest {
             int modifiers = method.getModifiers();
             if (Modifier.isFinal(modifiers) || !Modifier.isProtected(modifiers)
                     || Modifier.isStatic(modifiers)) {
-                Assert.fail(
-                        "isThis has invalid modifiers, CDI proxies will not work.");
+                fail("isThis has invalid modifiers, CDI proxies will not work.");
             }
         } catch (SecurityException e) {
             // Ignore, no can do
         } catch (NoSuchMethodException e) {
-            Assert.fail("isThis is missing, CDI proxies will not work.");
+            fail("isThis is missing, CDI proxies will not work.");
         }
     }
 
diff --git a/server/src/test/java/com/vaadin/server/AbstractClientConnectorTest.java b/server/src/test/java/com/vaadin/server/AbstractClientConnectorTest.java
index 4a6a2f5647..b4e4f95194 100644
--- a/server/src/test/java/com/vaadin/server/AbstractClientConnectorTest.java
+++ b/server/src/test/java/com/vaadin/server/AbstractClientConnectorTest.java
@@ -15,6 +15,11 @@
  */
 package com.vaadin.server;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
@@ -27,7 +32,6 @@ import java.net.URL;
 import java.util.Map;
 
 import org.apache.commons.io.IOUtils;
-import org.junit.Assert;
 import org.junit.Test;
 import org.mockito.Mockito;
 
@@ -51,9 +55,9 @@ public class AbstractClientConnectorTest {
         Mockito.doCallRealMethod().when(mock).registerRpc(implementation);
         try {
             mock.registerRpc(implementation);
-            Assert.fail("expected exception");
+            fail("expected exception");
         } catch (Exception expected) {
-            Assert.assertEquals(
+            assertEquals(
                     "Use registerRpc(T implementation, Class<T> rpcInterfaceType) "
                             + "if the Rpc implementation implements more than one interface",
                     expected.getMessage());
@@ -93,7 +97,7 @@ public class AbstractClientConnectorTest {
                 "com.vaadin.server.AbstractClientConnector");
         stateTypeCache.put(classRef.get(), null);
         int size = stateTypeCache.size();
-        Assert.assertNotNull("Class should not yet be garbage collected",
+        assertNotNull("Class should not yet be garbage collected",
                 classRef.get());
 
         for (int i = 0; i < 100; ++i) {
@@ -103,8 +107,8 @@ public class AbstractClientConnectorTest {
             }
             Thread.sleep(100);
         }
-        Assert.assertTrue(stateTypeCache.size() < size);
-        Assert.assertNull("Class should be garbage collected", classRef.get());
+        assertTrue(stateTypeCache.size() < size);
+        assertNull("Class should be garbage collected", classRef.get());
     }
 
     private WeakReference<Class<?>> loadClass(String name)
@@ -161,8 +165,7 @@ public class AbstractClientConnectorTest {
             if (!name.startsWith("com.vaadin.")) {
                 return super.loadClass(name);
             }
-            String path = name.replace('.', '/')
-                    .concat(".class");
+            String path = name.replace('.', '/').concat(".class");
             URL resource = Thread.currentThread().getContextClassLoader()
                     .getResource(path);
             try (InputStream stream = resource.openStream()) {
diff --git a/server/src/test/java/com/vaadin/server/AbstractDeploymentConfigurationTest.java b/server/src/test/java/com/vaadin/server/AbstractDeploymentConfigurationTest.java
index 2d4e7fad0a..97918d27dc 100644
--- a/server/src/test/java/com/vaadin/server/AbstractDeploymentConfigurationTest.java
+++ b/server/src/test/java/com/vaadin/server/AbstractDeploymentConfigurationTest.java
@@ -15,10 +15,11 @@
  */
 package com.vaadin.server;
 
+import static org.junit.Assert.assertEquals;
+
 import java.util.Properties;
 import java.util.UUID;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.shared.communication.PushMode;
@@ -35,8 +36,8 @@ public class AbstractDeploymentConfigurationTest {
         String ui = UUID.randomUUID().toString();
         DeploymentConfiguration config = getConfig(VaadinSession.UI_PARAMETER,
                 ui);
-        Assert.assertEquals("Unexpected UI class configuration option value",
-                ui, config.getUIClassName());
+        assertEquals("Unexpected UI class configuration option value", ui,
+                config.getUIClassName());
     }
 
     @Test
@@ -44,8 +45,7 @@ public class AbstractDeploymentConfigurationTest {
         String uiProvider = UUID.randomUUID().toString();
         DeploymentConfiguration config = getConfig(
                 Constants.SERVLET_PARAMETER_UI_PROVIDER, uiProvider);
-        Assert.assertEquals(
-                "Unexpected UI providerclass configuration option value",
+        assertEquals("Unexpected UI providerclass configuration option value",
                 uiProvider, config.getUIProviderClassName());
     }
 
@@ -54,7 +54,7 @@ public class AbstractDeploymentConfigurationTest {
         String widgetset = UUID.randomUUID().toString();
         DeploymentConfiguration config = getConfig(
                 Constants.PARAMETER_WIDGETSET, widgetset);
-        Assert.assertEquals("Unexpected widgetset configuration option value",
+        assertEquals("Unexpected widgetset configuration option value",
                 widgetset, config.getWidgetset(null));
     }
 
@@ -62,7 +62,7 @@ public class AbstractDeploymentConfigurationTest {
     public void getWidgetset_noWidgetsetPropertyValue_returnsProvidedDefaultValue() {
         DeploymentConfiguration config = getConfig(null, null);
         String widgetset = UUID.randomUUID().toString();
-        Assert.assertEquals("Unexpected widgetset configuration option value",
+        assertEquals("Unexpected widgetset configuration option value",
                 widgetset, config.getWidgetset(widgetset));
     }
 
@@ -71,8 +71,7 @@ public class AbstractDeploymentConfigurationTest {
         String resources = UUID.randomUUID().toString();
         DeploymentConfiguration config = getConfig(
                 Constants.PARAMETER_VAADIN_RESOURCES, resources);
-        Assert.assertEquals(
-                "Unexpected resources path configuration option value",
+        assertEquals("Unexpected resources path configuration option value",
                 resources, config.getResourcesPath());
     }
 
@@ -80,7 +79,7 @@ public class AbstractDeploymentConfigurationTest {
     public void getClassLoader_returnsClassloaderPropertyValue() {
         String classLoader = UUID.randomUUID().toString();
         DeploymentConfiguration config = getConfig("ClassLoader", classLoader);
-        Assert.assertEquals("Unexpected classLoader configuration option value",
+        assertEquals("Unexpected classLoader configuration option value",
                 classLoader, config.getClassLoaderName());
     }
 
diff --git a/server/src/test/java/com/vaadin/server/BootstrapHandlerTest.java b/server/src/test/java/com/vaadin/server/BootstrapHandlerTest.java
index 3530d105a3..2f96fad56f 100644
--- a/server/src/test/java/com/vaadin/server/BootstrapHandlerTest.java
+++ b/server/src/test/java/com/vaadin/server/BootstrapHandlerTest.java
@@ -15,9 +15,10 @@
  */
 package com.vaadin.server;
 
+import static org.junit.Assert.assertEquals;
+
 import java.util.Properties;
 
-import org.junit.Assert;
 import org.junit.Test;
 import org.mockito.Mockito;
 
@@ -105,7 +106,6 @@ public class BootstrapHandlerTest {
         Mockito.when(session.getBrowser()).thenReturn(browser);
         Mockito.when(session.getConfiguration()).thenReturn(configuration);
 
-        Assert.assertEquals(expectedUrl,
-                resolver.resolveVaadinUri(frontendUrl));
+        assertEquals(expectedUrl, resolver.resolveVaadinUri(frontendUrl));
     }
 }
diff --git a/server/src/test/java/com/vaadin/server/BrowserWindowOpenerTest.java b/server/src/test/java/com/vaadin/server/BrowserWindowOpenerTest.java
index 726f4ea549..ef8420655f 100644
--- a/server/src/test/java/com/vaadin/server/BrowserWindowOpenerTest.java
+++ b/server/src/test/java/com/vaadin/server/BrowserWindowOpenerTest.java
@@ -16,9 +16,11 @@
 package com.vaadin.server;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
 
 import org.easymock.EasyMock;
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.shared.communication.URLReference;
@@ -39,14 +41,14 @@ public class BrowserWindowOpenerTest {
 
         assertEquals("Unexpected resource is got on getResource() method",
                 resource, opener.getResource());
-        Assert.assertNull("Unexpected resource is got on getUrl() method",
+        assertNull("Unexpected resource is got on getUrl() method",
                 opener.getUrl());
 
         URLReference ref = opener.getState(false).resources
                 .get(BrowserWindowOpenerState.locationResource);
-        Assert.assertTrue("Url reference in the state is not ResourceReference",
+        assertTrue("Url reference in the state is not ResourceReference",
                 ref instanceof ResourceReference);
-        Assert.assertEquals("Unexpected resource saved in state", resource,
+        assertEquals("Unexpected resource saved in state", resource,
                 ((ResourceReference) ref).getResource());
     }
 
@@ -59,18 +61,17 @@ public class BrowserWindowOpenerTest {
 
         assertEquals("Unexpected URL is got on getURL() method", url,
                 opener.getUrl());
-        Assert.assertNotNull(
-                "Unexpected resource is got on getResource() method",
+        assertNotNull("Unexpected resource is got on getResource() method",
                 opener.getResource());
 
         URLReference ref = opener.getState(false).resources
                 .get(BrowserWindowOpenerState.locationResource);
-        Assert.assertTrue("Url reference in the state is not ResourceReference",
+        assertTrue("Url reference in the state is not ResourceReference",
                 ref instanceof ResourceReference);
         Resource resource = ((ResourceReference) ref).getResource();
-        Assert.assertTrue("Resource reference is not ExternalResource",
+        assertTrue("Resource reference is not ExternalResource",
                 resource instanceof ExternalResource);
-        Assert.assertEquals("Unexpected URL in resource saved in state", url,
+        assertEquals("Unexpected URL in resource saved in state", url,
                 ((ExternalResource) resource).getURL());
     }
 
diff --git a/server/src/test/java/com/vaadin/server/ConnectorResourceHandlerTest.java b/server/src/test/java/com/vaadin/server/ConnectorResourceHandlerTest.java
index 57b8ed8ff4..72eb5ec26e 100644
--- a/server/src/test/java/com/vaadin/server/ConnectorResourceHandlerTest.java
+++ b/server/src/test/java/com/vaadin/server/ConnectorResourceHandlerTest.java
@@ -15,11 +15,12 @@
  */
 package com.vaadin.server;
 
+import static org.junit.Assert.assertTrue;
+
 import java.io.IOException;
 
 import org.easymock.EasyMock;
 import org.easymock.IMocksControl;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -95,7 +96,7 @@ public class ConnectorResourceHandlerTest {
         }
 
         ConnectorResourceHandler handler = new ConnectorResourceHandler();
-        Assert.assertTrue(handler.handleRequest(session, request, response));
+        assertTrue(handler.handleRequest(session, request, response));
 
         EasyMock.verify(errorHandler);
     }
diff --git a/server/src/test/java/com/vaadin/server/DedicatedStateTest.java b/server/src/test/java/com/vaadin/server/DedicatedStateTest.java
index 3a21d136f7..009682ae88 100644
--- a/server/src/test/java/com/vaadin/server/DedicatedStateTest.java
+++ b/server/src/test/java/com/vaadin/server/DedicatedStateTest.java
@@ -15,11 +15,14 @@
  */
 package com.vaadin.server;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.fail;
+
 import java.lang.reflect.Method;
 import java.util.HashSet;
 import java.util.Set;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.navigator.Navigator;
@@ -58,7 +61,7 @@ public class DedicatedStateTest {
         Class<?> superclass = clazz.getSuperclass();
         if (!clazz.equals(AbstractClientConnector.class)
                 && !superclass.equals(AbstractExtension.class)) {
-            Assert.assertNotEquals(
+            assertNotEquals(
                     "Class " + clazz
                             + " has the same state type as its super class "
                             + clazz.getSuperclass(),
@@ -67,9 +70,9 @@ public class DedicatedStateTest {
         try {
             Method getStateOneArg = clazz.getDeclaredMethod("getState",
                     boolean.class);
-            Assert.assertEquals(stateType, getStateOneArg.getReturnType());
+            assertEquals(stateType, getStateOneArg.getReturnType());
         } catch (NoSuchMethodException e) {
-            Assert.fail("Class " + clazz
+            fail("Class " + clazz
                     + " doesn't have its own getState(boolean) method");
         } catch (SecurityException e) {
             throw new RuntimeException(e);
@@ -80,8 +83,7 @@ public class DedicatedStateTest {
         try {
             return clazz.getDeclaredMethod("getState");
         } catch (NoSuchMethodException e) {
-            Assert.fail("Class " + clazz
-                    + " doesn't have its own getState() method");
+            fail("Class " + clazz + " doesn't have its own getState() method");
             return null;
         } catch (SecurityException e) {
             throw new RuntimeException(e);
diff --git a/server/src/test/java/com/vaadin/server/DefaultDeploymentConfigurationTest.java b/server/src/test/java/com/vaadin/server/DefaultDeploymentConfigurationTest.java
index 41fc4f0077..4bbf165770 100644
--- a/server/src/test/java/com/vaadin/server/DefaultDeploymentConfigurationTest.java
+++ b/server/src/test/java/com/vaadin/server/DefaultDeploymentConfigurationTest.java
@@ -15,9 +15,10 @@
  */
 package com.vaadin.server;
 
+import static org.junit.Assert.assertEquals;
+
 import java.util.Properties;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 /**
@@ -37,7 +38,7 @@ public class DefaultDeploymentConfigurationTest {
         System.setProperty(prop, value);
         DefaultDeploymentConfiguration config = new DefaultDeploymentConfiguration(
                 clazz, new Properties());
-        Assert.assertEquals(value, config.getSystemProperty(prop));
+        assertEquals(value, config.getSystemProperty(prop));
     }
 
     @Test
@@ -50,6 +51,6 @@ public class DefaultDeploymentConfigurationTest {
                 value);
         DefaultDeploymentConfiguration config = new DefaultDeploymentConfiguration(
                 DefaultDeploymentConfigurationTest.class, new Properties());
-        Assert.assertEquals(value, config.getSystemProperty(prop));
+        assertEquals(value, config.getSystemProperty(prop));
     }
 }
diff --git a/server/src/test/java/com/vaadin/server/DragAndDropServiceTest.java b/server/src/test/java/com/vaadin/server/DragAndDropServiceTest.java
index 71e3782fcd..370bb490aa 100644
--- a/server/src/test/java/com/vaadin/server/DragAndDropServiceTest.java
+++ b/server/src/test/java/com/vaadin/server/DragAndDropServiceTest.java
@@ -15,6 +15,8 @@
  */
 package com.vaadin.server;
 
+import static org.junit.Assert.assertTrue;
+
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
@@ -25,7 +27,6 @@ import java.util.logging.Logger;
 import java.util.logging.StreamHandler;
 
 import org.easymock.EasyMock;
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.event.dd.DropHandler;
@@ -64,9 +65,9 @@ public class DragAndDropServiceTest {
                 EasyMock.createMock(VaadinSession.class));
         service.changeVariables(null, variables);
 
-        Assert.assertTrue("isConnectorEnabled() method is not called",
+        assertTrue("isConnectorEnabled() method is not called",
                 isConnectorEnabledCalled[0]);
-        Assert.assertTrue("No warning on drop from disabled source",
+        assertTrue("No warning on drop from disabled source",
                 levels.contains(Level.WARNING));
 
     }
@@ -89,9 +90,9 @@ public class DragAndDropServiceTest {
                 EasyMock.createMock(VaadinSession.class));
         service.changeVariables(null, variables);
 
-        Assert.assertTrue("isConnectorEnabled() method is not called",
+        assertTrue("isConnectorEnabled() method is not called",
                 target.isConnectorEnabledCalled());
-        Assert.assertTrue("No warning on drop to disabled target",
+        assertTrue("No warning on drop to disabled target",
                 levels.contains(Level.WARNING));
 
     }
diff --git a/server/src/test/java/com/vaadin/server/JSONSerializerTest.java b/server/src/test/java/com/vaadin/server/JSONSerializerTest.java
index 250d6831f4..406b798193 100644
--- a/server/src/test/java/com/vaadin/server/JSONSerializerTest.java
+++ b/server/src/test/java/com/vaadin/server/JSONSerializerTest.java
@@ -15,12 +15,14 @@
  */
 package com.vaadin.server;
 
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+
 import java.lang.reflect.Type;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.Map;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.server.JsonCodec.BeanProperty;
@@ -90,7 +92,7 @@ public class JSONSerializerTest {
         inputArray.set(1, Json.createNull());
         UidlValue decodedObject = (UidlValue) JsonCodec
                 .decodeInternalType(UidlValue.class, true, inputArray, null);
-        Assert.assertNull(decodedObject.getValue());
+        assertNull(decodedObject.getValue());
     }
 
     @Test(expected = JsonException.class)
@@ -106,8 +108,7 @@ public class JSONSerializerTest {
             Type type) throws Exception {
         Object serverSideDecoded = JsonCodec.decodeInternalOrCustomType(type,
                 encoded, null);
-        Assert.assertTrue("Server decoded",
-                equals(original, serverSideDecoded));
+        assertTrue("Server decoded", equals(original, serverSideDecoded));
 
     }
 
diff --git a/server/src/test/java/com/vaadin/server/JsonEqualsTest.java b/server/src/test/java/com/vaadin/server/JsonEqualsTest.java
index e92254921f..833c20e496 100644
--- a/server/src/test/java/com/vaadin/server/JsonEqualsTest.java
+++ b/server/src/test/java/com/vaadin/server/JsonEqualsTest.java
@@ -15,7 +15,9 @@
  */
 package com.vaadin.server;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import org.junit.Test;
 
 import elemental.json.Json;
@@ -29,7 +31,7 @@ public class JsonEqualsTest {
     public void differentTypes_notEqual() {
         boolean equals = JsonCodec.jsonEquals(Json.create(5), Json.create("5"));
 
-        Assert.assertFalse("Different types should not be equal", equals);
+        assertFalse("Different types should not be equal", equals);
     }
 
     @Test
@@ -37,7 +39,7 @@ public class JsonEqualsTest {
         boolean equals = JsonCodec.jsonEquals(Json.createNull(),
                 Json.createNull());
 
-        Assert.assertTrue("Null and null should be equal", equals);
+        assertTrue("Null and null should be equal", equals);
     }
 
     @Test
@@ -45,7 +47,7 @@ public class JsonEqualsTest {
         boolean equals = JsonCodec.jsonEquals(Json.create(true),
                 Json.create(false));
 
-        Assert.assertFalse("Different booleans should not be equal", equals);
+        assertFalse("Different booleans should not be equal", equals);
     }
 
     @Test
@@ -53,14 +55,14 @@ public class JsonEqualsTest {
         boolean equals = JsonCodec.jsonEquals(Json.create(false),
                 Json.create(false));
 
-        Assert.assertTrue("Same booleans should be equal", equals);
+        assertTrue("Same booleans should be equal", equals);
     }
 
     @Test
     public void differentNumbers_notEqual() {
         boolean equals = JsonCodec.jsonEquals(Json.create(2), Json.create(5.6));
 
-        Assert.assertFalse("Different numbers should not be equal", equals);
+        assertFalse("Different numbers should not be equal", equals);
     }
 
     @Test
@@ -68,7 +70,7 @@ public class JsonEqualsTest {
         boolean equals = JsonCodec.jsonEquals(Json.create(3.14),
                 Json.create(3.14));
 
-        Assert.assertTrue("Same numbers should be equal", equals);
+        assertTrue("Same numbers should be equal", equals);
     }
 
     @Test
@@ -76,7 +78,7 @@ public class JsonEqualsTest {
         boolean equals = JsonCodec.jsonEquals(Json.create("abc"),
                 Json.create("def"));
 
-        Assert.assertFalse("Different strings should not be equal", equals);
+        assertFalse("Different strings should not be equal", equals);
     }
 
     @Test
@@ -84,7 +86,7 @@ public class JsonEqualsTest {
         boolean equals = JsonCodec.jsonEquals(Json.create("abc"),
                 Json.create("abc"));
 
-        Assert.assertTrue("Same strings should be equal", equals);
+        assertTrue("Same strings should be equal", equals);
     }
 
     @Test
@@ -96,8 +98,8 @@ public class JsonEqualsTest {
 
         boolean equals = JsonCodec.jsonEquals(o1, o2);
 
-        Assert.assertFalse(
-                "Object with different key counts should not be equal", equals);
+        assertFalse("Object with different key counts should not be equal",
+                equals);
     }
 
     @Test
@@ -110,8 +112,7 @@ public class JsonEqualsTest {
 
         boolean equals = JsonCodec.jsonEquals(o1, o2);
 
-        Assert.assertFalse("Object with different keys should not be equal",
-                equals);
+        assertFalse("Object with different keys should not be equal", equals);
     }
 
     @Test
@@ -124,8 +125,7 @@ public class JsonEqualsTest {
 
         boolean equals = JsonCodec.jsonEquals(o1, o2);
 
-        Assert.assertFalse(
-                "Object with different child values should not be equal",
+        assertFalse("Object with different child values should not be equal",
                 equals);
     }
 
@@ -136,7 +136,7 @@ public class JsonEqualsTest {
 
         boolean equals = JsonCodec.jsonEquals(o1, o2);
 
-        Assert.assertTrue("Empty objects should be equal", equals);
+        assertTrue("Empty objects should be equal", equals);
     }
 
     @Test
@@ -149,7 +149,7 @@ public class JsonEqualsTest {
 
         boolean equals = JsonCodec.jsonEquals(o1, o2);
 
-        Assert.assertTrue("Same objects should be equal", equals);
+        assertTrue("Same objects should be equal", equals);
     }
 
     @Test
@@ -162,7 +162,7 @@ public class JsonEqualsTest {
 
         boolean equals = JsonCodec.jsonEquals(o1, o2);
 
-        Assert.assertTrue("Same objects should be equal", equals);
+        assertTrue("Same objects should be equal", equals);
     }
 
     @Test
@@ -174,8 +174,7 @@ public class JsonEqualsTest {
 
         boolean equals = JsonCodec.jsonEquals(a1, a2);
 
-        Assert.assertFalse("Arrays with different sizes should not be equal",
-                equals);
+        assertFalse("Arrays with different sizes should not be equal", equals);
     }
 
     @Test
@@ -188,7 +187,7 @@ public class JsonEqualsTest {
 
         boolean equals = JsonCodec.jsonEquals(a1, a2);
 
-        Assert.assertFalse("Arrays with different content should not be equal",
+        assertFalse("Arrays with different content should not be equal",
                 equals);
     }
 
@@ -204,8 +203,7 @@ public class JsonEqualsTest {
 
         boolean equals = JsonCodec.jsonEquals(a1, a2);
 
-        Assert.assertFalse("Arrays with different order should not be equal",
-                equals);
+        assertFalse("Arrays with different order should not be equal", equals);
     }
 
     @Test
@@ -215,7 +213,7 @@ public class JsonEqualsTest {
 
         boolean equals = JsonCodec.jsonEquals(a1, a2);
 
-        Assert.assertTrue("Empty arrays should be equal", equals);
+        assertTrue("Empty arrays should be equal", equals);
     }
 
     @Test
@@ -230,7 +228,7 @@ public class JsonEqualsTest {
 
         boolean equals = JsonCodec.jsonEquals(a1, a2);
 
-        Assert.assertTrue("Same arrays should be equal", equals);
+        assertTrue("Same arrays should be equal", equals);
     }
 
     @Test
@@ -243,7 +241,7 @@ public class JsonEqualsTest {
 
         boolean equals = JsonCodec.jsonEquals(a1, a2);
 
-        Assert.assertTrue("Same arrays should be equal", equals);
+        assertTrue("Same arrays should be equal", equals);
     }
 
     @Test
@@ -251,7 +249,7 @@ public class JsonEqualsTest {
         boolean equals = JsonCodec.jsonEquals(createDeeplyNestedValue(1),
                 createDeeplyNestedValue(2));
 
-        Assert.assertFalse("Values should not be equal", equals);
+        assertFalse("Values should not be equal", equals);
     }
 
     @Test
@@ -259,7 +257,7 @@ public class JsonEqualsTest {
         boolean equals = JsonCodec.jsonEquals(createDeeplyNestedValue(1),
                 createDeeplyNestedValue(1));
 
-        Assert.assertTrue("Values should be equal", equals);
+        assertTrue("Values should be equal", equals);
     }
 
     private static JsonValue createDeeplyNestedValue(int leafValue) {
diff --git a/server/src/test/java/com/vaadin/server/LocaleServiceTest.java b/server/src/test/java/com/vaadin/server/LocaleServiceTest.java
index 7742c2ae30..ec028aa5cd 100644
--- a/server/src/test/java/com/vaadin/server/LocaleServiceTest.java
+++ b/server/src/test/java/com/vaadin/server/LocaleServiceTest.java
@@ -1,12 +1,13 @@
 package com.vaadin.server;
 
+import static org.junit.Assert.assertEquals;
+
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.Mockito;
@@ -956,16 +957,16 @@ public class LocaleServiceTest {
     @Test
     public void localeDateTimeFormat() {
         for (Locale l : expectedLocaleData.keySet()) {
-            Assert.assertEquals("Error verifying locale " + l,
+            assertEquals("Error verifying locale " + l,
                     expectedLocaleData.get(l).dateFormat,
                     localeService.createLocaleData(l).dateFormat);
-            Assert.assertEquals("Error verifying locale " + l,
+            assertEquals("Error verifying locale " + l,
                     expectedLocaleData.get(l).twelveHourClock,
                     localeService.createLocaleData(l).twelveHourClock);
-            Assert.assertEquals("Error verifying locale " + l,
+            assertEquals("Error verifying locale " + l,
                     expectedLocaleData.get(l).am,
                     localeService.createLocaleData(l).am);
-            Assert.assertEquals("Error verifying locale " + l,
+            assertEquals("Error verifying locale " + l,
                     expectedLocaleData.get(l).pm,
                     localeService.createLocaleData(l).pm);
         }
@@ -1023,4 +1024,4 @@ public class LocaleServiceTest {
                 + id.replaceAll("_", "\",\"") + "\"), " + field + ");");
     }
 
-}
\ No newline at end of file
+}
diff --git a/server/src/test/java/com/vaadin/server/PageTest.java b/server/src/test/java/com/vaadin/server/PageTest.java
index 3a8c5a0ba1..42ab59dc51 100644
--- a/server/src/test/java/com/vaadin/server/PageTest.java
+++ b/server/src/test/java/com/vaadin/server/PageTest.java
@@ -15,8 +15,9 @@
  */
 package com.vaadin.server;
 
+import static org.junit.Assert.assertFalse;
+
 import org.easymock.EasyMock;
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.server.Page.BrowserWindowResizeEvent;
@@ -43,8 +44,7 @@ public class PageTest {
 
         page.updateBrowserWindowSize(0, 0, true);
 
-        Assert.assertFalse("Listener is called after removal",
-                listener.isCalled());
+        assertFalse("Listener is called after removal", listener.isCalled());
     }
 
     @Test
@@ -56,8 +56,7 @@ public class PageTest {
                 .createMock(BrowserWindowResizeListener.class);
         page.removeBrowserWindowResizeListener(listener);
 
-        Assert.assertFalse(
-                "Page state 'hasResizeListeners' property has wrong value",
+        assertFalse("Page state 'hasResizeListeners' property has wrong value",
                 page.getState(false).hasResizeListeners);
     }
 
diff --git a/server/src/test/java/com/vaadin/server/RemoveListenersDeprecatedTest.java b/server/src/test/java/com/vaadin/server/RemoveListenersDeprecatedTest.java
index d597ab3539..0e7426232d 100644
--- a/server/src/test/java/com/vaadin/server/RemoveListenersDeprecatedTest.java
+++ b/server/src/test/java/com/vaadin/server/RemoveListenersDeprecatedTest.java
@@ -1,5 +1,9 @@
 package com.vaadin.server;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.util.ArrayList;
@@ -7,7 +11,6 @@ import java.util.List;
 import java.util.function.Predicate;
 import java.util.regex.Pattern;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.data.provider.AbstractDataProvider;
@@ -47,11 +50,10 @@ public class RemoveListenersDeprecatedTest {
                 if (addPattern.matcher(method.getName()).matches()
                         && method.getAnnotation(Deprecated.class) == null) {
                     Class<?> returnType = method.getReturnType();
-                    Assert.assertEquals(
-                            "Method " + method.getName()
-                                    + " is not deprectated in class "
-                                    + serverClass.getName()
-                                    + " and doesn't return a Registration object",
+                    assertEquals("Method " + method.getName()
+                            + " is not deprectated in class "
+                            + serverClass.getName()
+                            + " and doesn't return a Registration object",
                             Registration.class, returnType);
                 }
                 if (ALLOW_REMOVE_LISTENER.stream()
@@ -60,7 +62,7 @@ public class RemoveListenersDeprecatedTest {
                 }
 
                 if (removePattern.matcher(method.getName()).matches()) {
-                    Assert.assertNotNull(
+                    assertNotNull(
                             "Method " + method.getName() + " in class "
                                     + serverClass.getName()
                                     + " has not been marked as deprecated.",
@@ -68,7 +70,7 @@ public class RemoveListenersDeprecatedTest {
                 }
             }
         }
-        Assert.assertTrue(count > 0);
+        assertTrue(count > 0);
     }
 
     private static boolean acceptMethodEventSource(Method method) {
diff --git a/server/src/test/java/com/vaadin/server/TestAbstractApplicationServletStaticFilesLocation.java b/server/src/test/java/com/vaadin/server/TestAbstractApplicationServletStaticFilesLocation.java
index 3017bc3e37..08ad5a9bac 100644
--- a/server/src/test/java/com/vaadin/server/TestAbstractApplicationServletStaticFilesLocation.java
+++ b/server/src/test/java/com/vaadin/server/TestAbstractApplicationServletStaticFilesLocation.java
@@ -3,13 +3,13 @@ package com.vaadin.server;
 import static org.easymock.EasyMock.createMock;
 import static org.easymock.EasyMock.expect;
 import static org.easymock.EasyMock.replay;
+import static org.junit.Assert.assertEquals;
 
 import java.net.MalformedURLException;
 import java.net.URL;
 
 import javax.servlet.http.HttpServletRequest;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -34,30 +34,30 @@ public class TestAbstractApplicationServletStaticFilesLocation {
         // should return . (relative url resolving to /contextpath)
         location = testLocation("http://dummy.host:8080", "/contextpath",
                 "/servlet", "");
-        Assert.assertEquals(".", location);
+        assertEquals(".", location);
 
         // http://dummy.host:8080/contextpath/servlet/
         // should return ./.. (relative url resolving to /contextpath)
         location = testLocation("http://dummy.host:8080", "/contextpath",
                 "/servlet", "/");
-        Assert.assertEquals("./..", location);
+        assertEquals("./..", location);
 
         // http://dummy.host:8080/servlet
         // should return "."
         location = testLocation("http://dummy.host:8080", "", "/servlet", "");
-        Assert.assertEquals(".", location);
+        assertEquals(".", location);
 
         // http://dummy.host/contextpath/servlet/extra/stuff
         // should return ./../.. (relative url resolving to /contextpath)
         location = testLocation("http://dummy.host", "/contextpath", "/servlet",
                 "/extra/stuff");
-        Assert.assertEquals("./../..", location);
+        assertEquals("./../..", location);
 
         // http://dummy.host/context/path/servlet/extra/stuff
         // should return ./../.. (relative url resolving to /context/path)
         location = testLocation("http://dummy.host", "/context/path",
                 "/servlet", "/extra/stuff");
-        Assert.assertEquals("./../..", location);
+        assertEquals("./../..", location);
 
         /* Include requests */
         // Include request support dropped with support for portlet1
diff --git a/server/src/test/java/com/vaadin/server/UIProviderTest.java b/server/src/test/java/com/vaadin/server/UIProviderTest.java
index f55e489c0a..92b37fed2f 100644
--- a/server/src/test/java/com/vaadin/server/UIProviderTest.java
+++ b/server/src/test/java/com/vaadin/server/UIProviderTest.java
@@ -15,12 +15,14 @@
  */
 package com.vaadin.server;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+
 import java.lang.annotation.ElementType;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.annotations.Theme;
@@ -35,43 +37,40 @@ public class UIProviderTest {
 
     @Test
     public void getAnnotationFor_widgetsetAnnotationForSubclass_annotationFound() {
-        Assert.assertNotNull("Widgetset annotation is not found for subclass",
+        assertNotNull("Widgetset annotation is not found for subclass",
                 UIProvider.getAnnotationFor(TestClass.class, Widgetset.class));
     }
 
     @Test
     public void getAnnotationFor_themeAnnotationForSubclass_annotationFound() {
-        Assert.assertNotNull("Theme annotation is not found for subclass",
+        assertNotNull("Theme annotation is not found for subclass",
                 UIProvider.getAnnotationFor(TestClass.class, Theme.class));
     }
 
     @Test
     public void getAnnotationFor_themeAnnotationForSubclass_annotationOverridden() {
-        Assert.assertEquals(
-                "Theme annotation is not overridden correctly in subclass", "c",
-                UIProvider.getAnnotationFor(TestClass.class, Theme.class)
+        assertEquals("Theme annotation is not overridden correctly in subclass",
+                "c", UIProvider.getAnnotationFor(TestClass.class, Theme.class)
                         .value());
     }
 
     @Test
     public void getAnnotationFor_notInheritedAnnotationForSubclass_annotationFound() {
-        Assert.assertNotNull(
-                "TestAnnotation annotation is not found for subclass",
+        assertNotNull("TestAnnotation annotation is not found for subclass",
                 UIProvider.getAnnotationFor(TestClass.class,
                         TestAnnotation.class));
     }
 
     @Test
     public void getAnnotationFor_directAnnotationForSubclass_annotationFound() {
-        Assert.assertNotNull(
-                "TestAnnotation1 annotation is not found for subclass",
+        assertNotNull("TestAnnotation1 annotation is not found for subclass",
                 UIProvider.getAnnotationFor(TestClass.class,
                         TestAnnotation1.class));
     }
 
     @Test
     public void getAnnotationFor_annotationInheritedFromInterface_annotationFound() {
-        Assert.assertNotNull("Theme annotation is not inherited from interface",
+        assertNotNull("Theme annotation is not inherited from interface",
                 UIProvider.getAnnotationFor(ClassImplementingInterface.class,
                         Theme.class));
     }
diff --git a/server/src/test/java/com/vaadin/server/VaadinPortletServiceTest.java b/server/src/test/java/com/vaadin/server/VaadinPortletServiceTest.java
index c109a62a79..ccd6aba6e5 100644
--- a/server/src/test/java/com/vaadin/server/VaadinPortletServiceTest.java
+++ b/server/src/test/java/com/vaadin/server/VaadinPortletServiceTest.java
@@ -17,12 +17,13 @@ package com.vaadin.server;
 
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.fail;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
 import java.util.concurrent.locks.ReentrantLock;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.Mockito;
@@ -211,9 +212,9 @@ public class VaadinPortletServiceTest {
                     .thenReturn(emptyWrappedSession);
 
             UI ui = sut.findUI(requestWithUIIDSet);
-            Assert.assertNull("Unset session did not return null", ui);
+            assertNull("Unset session did not return null", ui);
         } catch (NullPointerException e) {
-            Assert.fail("findUI threw a NullPointerException");
+            fail("findUI threw a NullPointerException");
         }
     }
 }
diff --git a/server/src/test/java/com/vaadin/server/VaadinServiceTest.java b/server/src/test/java/com/vaadin/server/VaadinServiceTest.java
index 7d6cc70146..6219be0a29 100644
--- a/server/src/test/java/com/vaadin/server/VaadinServiceTest.java
+++ b/server/src/test/java/com/vaadin/server/VaadinServiceTest.java
@@ -17,13 +17,13 @@ package com.vaadin.server;
 
 import static org.hamcrest.CoreMatchers.containsString;
 import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.Assert.assertEquals;
 
 import javax.servlet.ServletConfig;
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpSessionBindingEvent;
 
 import org.easymock.EasyMock;
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.shared.Registration;
@@ -72,20 +72,20 @@ public class VaadinServiceTest {
 
         MockVaadinSession vaadinSession = new MockVaadinSession(service);
         service.fireSessionDestroy(vaadinSession);
-        Assert.assertEquals(
+        assertEquals(
                 "'fireSessionDestroy' method doesn't call 'close' for the session",
                 1, vaadinSession.getCloseCount());
 
         vaadinSession.valueUnbound(
                 EasyMock.createMock(HttpSessionBindingEvent.class));
 
-        Assert.assertEquals(
+        assertEquals(
                 "'fireSessionDestroy' method may not call 'close' "
                         + "method for closing session",
                 1, vaadinSession.getCloseCount());
 
-        Assert.assertEquals("SessionDestroyListeners not called exactly once",
-                1, listener.callCount);
+        assertEquals("SessionDestroyListeners not called exactly once", 1,
+                listener.callCount);
     }
 
     @Test
@@ -164,7 +164,7 @@ public class VaadinServiceTest {
 
         CurrentInstance.set(String.class, "Original value");
         service.runPendingAccessTasks(session);
-        Assert.assertEquals(
+        assertEquals(
                 "Original CurrentInstance should be set after the task has been run",
                 "Original value", CurrentInstance.get(String.class));
     }
@@ -190,13 +190,13 @@ public class VaadinServiceTest {
         Registration remover2 = service.addServiceDestroyListener(listener2);
 
         service.destroy();
-        Assert.assertEquals(1, listener.callCount);
-        Assert.assertEquals(1, listener2.callCount);
+        assertEquals(1, listener.callCount);
+        assertEquals(1, listener2.callCount);
         service.removeServiceDestroyListener(listener);
         remover2.remove();
 
         service.destroy();
-        Assert.assertEquals(1, listener.callCount);
-        Assert.assertEquals(1, listener2.callCount);
+        assertEquals(1, listener.callCount);
+        assertEquals(1, listener2.callCount);
     }
 }
diff --git a/server/src/test/java/com/vaadin/server/VaadinServletConfigurationTest.java b/server/src/test/java/com/vaadin/server/VaadinServletConfigurationTest.java
index bc13afa4fd..5e6176df53 100644
--- a/server/src/test/java/com/vaadin/server/VaadinServletConfigurationTest.java
+++ b/server/src/test/java/com/vaadin/server/VaadinServletConfigurationTest.java
@@ -19,13 +19,16 @@
  */
 package com.vaadin.server;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import java.util.Properties;
 
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServletRequest;
 
 import org.easymock.EasyMock;
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.annotations.VaadinServletConfiguration;
@@ -43,7 +46,7 @@ public class VaadinServletConfigurationTest {
                 .getUIClass(new UIClassSelectionEvent(new VaadinServletRequest(
                         EasyMock.createMock(HttpServletRequest.class),
                         servlet.getService())));
-        Assert.assertEquals(MockUIContainingServlet.class, uiClass);
+        assertEquals(MockUIContainingServlet.class, uiClass);
     }
 
     @Test
@@ -53,16 +56,16 @@ public class VaadinServletConfigurationTest {
         DeploymentConfiguration configuration = servlet.getService()
                 .getDeploymentConfiguration();
 
-        Assert.assertTrue(configuration.isProductionMode());
-        Assert.assertTrue(configuration.isCloseIdleSessions());
-        Assert.assertEquals(1234, configuration.getHeartbeatInterval());
-        Assert.assertEquals(4321, configuration.getResourceCacheTime());
+        assertTrue(configuration.isProductionMode());
+        assertTrue(configuration.isCloseIdleSessions());
+        assertEquals(1234, configuration.getHeartbeatInterval());
+        assertEquals(4321, configuration.getResourceCacheTime());
 
         Class<? extends UI> uiClass = new DefaultUIProvider()
                 .getUIClass(new UIClassSelectionEvent(new VaadinServletRequest(
                         EasyMock.createMock(HttpServletRequest.class),
                         servlet.getService())));
-        Assert.assertEquals(MockUIContainingServlet.class, uiClass);
+        assertEquals(MockUIContainingServlet.class, uiClass);
     }
 
     @Test
@@ -77,18 +80,18 @@ public class VaadinServletConfigurationTest {
                 .getDeploymentConfiguration();
 
         // Values from servlet init params take precedence
-        Assert.assertEquals(1111, configuration.getHeartbeatInterval());
-        Assert.assertFalse(configuration.isProductionMode());
+        assertEquals(1111, configuration.getHeartbeatInterval());
+        assertFalse(configuration.isProductionMode());
 
         // Other params are as defined in the annotation
-        Assert.assertTrue(configuration.isCloseIdleSessions());
-        Assert.assertEquals(4321, configuration.getResourceCacheTime());
+        assertTrue(configuration.isCloseIdleSessions());
+        assertEquals(4321, configuration.getResourceCacheTime());
 
         Class<? extends UI> uiClass = new DefaultUIProvider()
                 .getUIClass(new UIClassSelectionEvent(new VaadinServletRequest(
                         EasyMock.createMock(HttpServletRequest.class),
                         servlet.getService())));
-        Assert.assertEquals(MockUIContainingServlet.class, uiClass);
+        assertEquals(MockUIContainingServlet.class, uiClass);
     }
 }
 
diff --git a/server/src/test/java/com/vaadin/server/VaadinServletServiceTest.java b/server/src/test/java/com/vaadin/server/VaadinServletServiceTest.java
index 24bb800a12..1630d3b968 100644
--- a/server/src/test/java/com/vaadin/server/VaadinServletServiceTest.java
+++ b/server/src/test/java/com/vaadin/server/VaadinServletServiceTest.java
@@ -3,6 +3,7 @@ package com.vaadin.server;
 import static org.easymock.EasyMock.createMock;
 import static org.easymock.EasyMock.expect;
 import static org.easymock.EasyMock.replay;
+import static org.junit.Assert.assertEquals;
 
 import java.net.MalformedURLException;
 import java.net.URL;
@@ -10,7 +11,6 @@ import java.net.URL;
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServletRequest;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -32,36 +32,36 @@ public class VaadinServletServiceTest {
         // should return . (relative url resolving to /contextpath)
         location = testLocation("http://dummy.host:8080", "/contextpath",
                 "/servlet", "");
-        Assert.assertEquals(".", location);
+        assertEquals(".", location);
 
         // http://dummy.host:8080/contextpath/servlet/
         // should return ./.. (relative url resolving to /contextpath)
         location = testLocation("http://dummy.host:8080", "/contextpath",
                 "/servlet", "/");
-        Assert.assertEquals("./..", location);
+        assertEquals("./..", location);
 
         // http://dummy.host:8080/servlet
         // should return "."
         location = testLocation("http://dummy.host:8080", "", "/servlet", "");
-        Assert.assertEquals(".", location);
+        assertEquals(".", location);
 
         // http://dummy.host/contextpath/servlet/extra/stuff
         // should return ./../.. (relative url resolving to /contextpath)
         location = testLocation("http://dummy.host", "/contextpath", "/servlet",
                 "/extra/stuff");
-        Assert.assertEquals("./../..", location);
+        assertEquals("./../..", location);
 
         // http://dummy.host/contextpath/servlet/extra/stuff/
         // should return ./../.. (relative url resolving to /contextpath)
         location = testLocation("http://dummy.host", "/contextpath", "/servlet",
                 "/extra/stuff/");
-        Assert.assertEquals("./../../..", location);
+        assertEquals("./../../..", location);
 
         // http://dummy.host/context/path/servlet/extra/stuff
         // should return ./../.. (relative url resolving to /context/path)
         location = testLocation("http://dummy.host", "/context/path",
                 "/servlet", "/extra/stuff");
-        Assert.assertEquals("./../..", location);
+        assertEquals("./../..", location);
 
     }
 
diff --git a/server/src/test/java/com/vaadin/server/VaadinServletTest.java b/server/src/test/java/com/vaadin/server/VaadinServletTest.java
index 296d4e8c40..13bde9699c 100644
--- a/server/src/test/java/com/vaadin/server/VaadinServletTest.java
+++ b/server/src/test/java/com/vaadin/server/VaadinServletTest.java
@@ -15,9 +15,11 @@
  */
 package com.vaadin.server;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
 import javax.servlet.http.HttpServletRequest;
 
-import org.junit.Assert;
 import org.junit.Test;
 import org.mockito.Mockito;
 
@@ -25,39 +27,39 @@ public class VaadinServletTest {
 
     @Test
     public void testGetLastPathParameter() {
-        Assert.assertEquals("",
+        assertEquals("",
                 VaadinServlet.getLastPathParameter("http://myhost.com"));
-        Assert.assertEquals(";a",
+        assertEquals(";a",
                 VaadinServlet.getLastPathParameter("http://myhost.com;a"));
-        Assert.assertEquals("",
+        assertEquals("",
                 VaadinServlet.getLastPathParameter("http://myhost.com/hello"));
-        Assert.assertEquals(";b=c", VaadinServlet
+        assertEquals(";b=c", VaadinServlet
                 .getLastPathParameter("http://myhost.com/hello;b=c"));
-        Assert.assertEquals("",
+        assertEquals("",
                 VaadinServlet.getLastPathParameter("http://myhost.com/hello/"));
-        Assert.assertEquals("", VaadinServlet
+        assertEquals("", VaadinServlet
                 .getLastPathParameter("http://myhost.com/hello;a/"));
-        Assert.assertEquals("", VaadinServlet
+        assertEquals("", VaadinServlet
                 .getLastPathParameter("http://myhost.com/hello;a=1/"));
-        Assert.assertEquals(";b", VaadinServlet
+        assertEquals(";b", VaadinServlet
                 .getLastPathParameter("http://myhost.com/hello/;b"));
-        Assert.assertEquals(";b=1", VaadinServlet
+        assertEquals(";b=1", VaadinServlet
                 .getLastPathParameter("http://myhost.com/hello/;b=1"));
-        Assert.assertEquals(";b=1,c=2", VaadinServlet
+        assertEquals(";b=1,c=2", VaadinServlet
                 .getLastPathParameter("http://myhost.com/hello/;b=1,c=2"));
-        Assert.assertEquals("", VaadinServlet
+        assertEquals("", VaadinServlet
                 .getLastPathParameter("http://myhost.com/hello/;b=1,c=2/"));
-        Assert.assertEquals("", VaadinServlet
+        assertEquals("", VaadinServlet
                 .getLastPathParameter("http://myhost.com/a;hello/;a/"));
-        Assert.assertEquals("", VaadinServlet
+        assertEquals("", VaadinServlet
                 .getLastPathParameter("http://myhost.com/a;hello/;a=1/"));
-        Assert.assertEquals(";b", VaadinServlet
+        assertEquals(";b", VaadinServlet
                 .getLastPathParameter("http://myhost.com/a;hello/;b"));
-        Assert.assertEquals(";b=1", VaadinServlet
+        assertEquals(";b=1", VaadinServlet
                 .getLastPathParameter("http://myhost.com/a;hello/;b=1"));
-        Assert.assertEquals(";b=1,c=2", VaadinServlet
+        assertEquals(";b=1,c=2", VaadinServlet
                 .getLastPathParameter("http://myhost.com/a;hello/;b=1,c=2"));
-        Assert.assertEquals("", VaadinServlet
+        assertEquals("", VaadinServlet
                 .getLastPathParameter("http://myhost.com/a;hello/;b=1,c=2/"));
     }
 
@@ -67,61 +69,59 @@ public class VaadinServletTest {
 
         // Mapping: /VAADIN/*
         // /VAADIN
-        Assert.assertNull(servlet
+        assertNull(servlet
                 .getStaticFilePath(createServletRequest("/VAADIN", null)));
         // /VAADIN/ - not really sensible but still interpreted as a resource
         // request
-        Assert.assertEquals("/VAADIN/", servlet
+        assertEquals("/VAADIN/", servlet
                 .getStaticFilePath(createServletRequest("/VAADIN", "/")));
         // /VAADIN/vaadinBootstrap.js
-        Assert.assertEquals("/VAADIN/vaadinBootstrap.js",
-                servlet.getStaticFilePath(createServletRequest("/VAADIN",
-                        "/vaadinBootstrap.js")));
+        assertEquals("/VAADIN/vaadinBootstrap.js", servlet.getStaticFilePath(
+                createServletRequest("/VAADIN", "/vaadinBootstrap.js")));
         // /VAADIN/foo bar.js
-        Assert.assertEquals("/VAADIN/foo bar.js", servlet.getStaticFilePath(
+        assertEquals("/VAADIN/foo bar.js", servlet.getStaticFilePath(
                 createServletRequest("/VAADIN", "/foo bar.js")));
         // /VAADIN/.. - not normalized and disallowed in this method
-        Assert.assertEquals("/VAADIN/..", servlet
+        assertEquals("/VAADIN/..", servlet
                 .getStaticFilePath(createServletRequest("/VAADIN", "/..")));
 
         // Mapping: /*
         // /
-        Assert.assertNull(
-                servlet.getStaticFilePath(createServletRequest("", null)));
+        assertNull(servlet.getStaticFilePath(createServletRequest("", null)));
         // /VAADIN
-        Assert.assertNull(
+        assertNull(
                 servlet.getStaticFilePath(createServletRequest("", "/VAADIN")));
         // /VAADIN/
-        Assert.assertEquals("/VAADIN/", servlet
+        assertEquals("/VAADIN/", servlet
                 .getStaticFilePath(createServletRequest("", "/VAADIN/")));
         // /VAADIN/foo bar.js
-        Assert.assertEquals("/VAADIN/foo bar.js", servlet.getStaticFilePath(
+        assertEquals("/VAADIN/foo bar.js", servlet.getStaticFilePath(
                 createServletRequest("", "/VAADIN/foo bar.js")));
         // /VAADIN/.. - not normalized and disallowed in this method
-        Assert.assertEquals("/VAADIN/..", servlet
+        assertEquals("/VAADIN/..", servlet
                 .getStaticFilePath(createServletRequest("", "/VAADIN/..")));
         // /BAADIN/foo.js
-        Assert.assertNull(servlet
+        assertNull(servlet
                 .getStaticFilePath(createServletRequest("", "/BAADIN/foo.js")));
 
         // Mapping: /myservlet/*
         // /myservlet
-        Assert.assertNull(servlet
+        assertNull(servlet
                 .getStaticFilePath(createServletRequest("/myservlet", null)));
         // /myservlet/VAADIN
-        Assert.assertNull(servlet.getStaticFilePath(
+        assertNull(servlet.getStaticFilePath(
                 createServletRequest("/myservlet", "/VAADIN")));
         // /myservlet/VAADIN/
-        Assert.assertEquals("/VAADIN/", servlet.getStaticFilePath(
+        assertEquals("/VAADIN/", servlet.getStaticFilePath(
                 createServletRequest("/myservlet", "/VAADIN/")));
         // /myservlet/VAADIN/foo bar.js
-        Assert.assertEquals("/VAADIN/foo bar.js", servlet.getStaticFilePath(
+        assertEquals("/VAADIN/foo bar.js", servlet.getStaticFilePath(
                 createServletRequest("/myservlet", "/VAADIN/foo bar.js")));
         // /myservlet/VAADIN/.. - not normalized and disallowed in this method
-        Assert.assertEquals("/VAADIN/..", servlet.getStaticFilePath(
+        assertEquals("/VAADIN/..", servlet.getStaticFilePath(
                 createServletRequest("/myservlet", "/VAADIN/..")));
         // /myservlet/BAADIN/foo.js
-        Assert.assertNull(servlet.getStaticFilePath(
+        assertNull(servlet.getStaticFilePath(
                 createServletRequest("/myservlet", "/BAADIN/foo.js")));
 
     }
diff --git a/server/src/test/java/com/vaadin/server/VaadinSessionTest.java b/server/src/test/java/com/vaadin/server/VaadinSessionTest.java
index a3d0746149..ccd610269c 100644
--- a/server/src/test/java/com/vaadin/server/VaadinSessionTest.java
+++ b/server/src/test/java/com/vaadin/server/VaadinSessionTest.java
@@ -15,6 +15,12 @@
  */
 package com.vaadin.server;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotSame;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
@@ -33,7 +39,6 @@ import javax.servlet.http.HttpSessionBindingEvent;
 
 import org.easymock.EasyMock;
 import org.easymock.IMocksControl;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -196,11 +201,11 @@ public class VaadinSessionTest implements Serializable {
         final AtomicBoolean detachCalled = new AtomicBoolean(false);
         ui.addDetachListener((DetachEvent event) -> {
             detachCalled.set(true);
-            Assert.assertEquals(ui, UI.getCurrent());
-            Assert.assertEquals(ui.getPage(), Page.getCurrent());
-            Assert.assertEquals(session, VaadinSession.getCurrent());
-            Assert.assertEquals(mockService, VaadinService.getCurrent());
-            Assert.assertEquals(mockServlet, VaadinServlet.getCurrent());
+            assertEquals(ui, UI.getCurrent());
+            assertEquals(ui.getPage(), Page.getCurrent());
+            assertEquals(session, VaadinSession.getCurrent());
+            assertEquals(mockService, VaadinService.getCurrent());
+            assertEquals(mockServlet, VaadinServlet.getCurrent());
         });
 
         session.valueUnbound(
@@ -211,7 +216,7 @@ public class VaadinSessionTest implements Serializable {
                                                     // VaadinService.fireSessionDestroy,
                                                     // we need to run the
                                                     // pending task ourselves
-        Assert.assertTrue(detachCalled.get());
+        assertTrue(detachCalled.get());
     }
 
     @Test
@@ -219,11 +224,11 @@ public class VaadinSessionTest implements Serializable {
         final AtomicBoolean detachCalled = new AtomicBoolean(false);
         ui.addDetachListener((DetachEvent event) -> {
             detachCalled.set(true);
-            Assert.assertEquals(ui, UI.getCurrent());
-            Assert.assertEquals(ui.getPage(), Page.getCurrent());
-            Assert.assertEquals(session, VaadinSession.getCurrent());
-            Assert.assertEquals(mockService, VaadinService.getCurrent());
-            Assert.assertEquals(mockServlet, VaadinServlet.getCurrent());
+            assertEquals(ui, UI.getCurrent());
+            assertEquals(ui.getPage(), Page.getCurrent());
+            assertEquals(session, VaadinSession.getCurrent());
+            assertEquals(mockService, VaadinService.getCurrent());
+            assertEquals(mockServlet, VaadinServlet.getCurrent());
         });
         CurrentInstance.clearAll();
         session.close();
@@ -234,7 +239,7 @@ public class VaadinSessionTest implements Serializable {
                                                     // VaadinService.fireSessionDestroy,
                                                     // we need to run the
                                                     // pending task ourselves
-        Assert.assertTrue(detachCalled.get());
+        assertTrue(detachCalled.get());
     }
 
     @Test
@@ -287,8 +292,8 @@ public class VaadinSessionTest implements Serializable {
         VaadinSession.setCurrent(session);
         session.lock();
         SerializationTestLabel label = new SerializationTestLabel();
-        Assert.assertEquals("Session should be set when instance is created",
-                session, label.session);
+        assertEquals("Session should be set when instance is created", session,
+                label.session);
 
         ui.setContent(label);
         int uiId = ui.getUIId();
@@ -307,11 +312,10 @@ public class VaadinSessionTest implements Serializable {
 
         VaadinSession deserializedSession = (VaadinSession) in.readObject();
 
-        Assert.assertNull("Current session shouldn't leak from deserialisation",
+        assertNull("Current session shouldn't leak from deserialisation",
                 VaadinSession.getCurrent());
 
-        Assert.assertNotSame("Should get a new session", session,
-                deserializedSession);
+        assertNotSame("Should get a new session", session, deserializedSession);
 
         // Restore http session and service instance so the session can be
         // locked
@@ -322,7 +326,7 @@ public class VaadinSessionTest implements Serializable {
         SerializationTestLabel deserializedLabel = (SerializationTestLabel) deserializedUi
                 .getContent();
 
-        Assert.assertEquals(
+        assertEquals(
                 "Current session should be available in SerializationTestLabel.readObject",
                 deserializedSession, deserializedLabel.session);
         deserializedSession.unlock();
@@ -335,20 +339,20 @@ public class VaadinSessionTest implements Serializable {
         ui.setContent(new Label() {
             private void writeObject(ObjectOutputStream out)
                     throws IOException {
-                Assert.assertTrue(session.hasLock());
+                assertTrue(session.hasLock());
                 lockChecked.set(true);
                 out.defaultWriteObject();
             }
         });
 
         session.unlock();
-        Assert.assertFalse(session.hasLock());
+        assertFalse(session.hasLock());
 
         ObjectOutputStream out = new ObjectOutputStream(
                 new ByteArrayOutputStream());
         out.writeObject(session);
 
-        Assert.assertFalse(session.hasLock());
-        Assert.assertTrue(lockChecked.get());
+        assertFalse(session.hasLock());
+        assertTrue(lockChecked.get());
     }
 }
diff --git a/server/src/test/java/com/vaadin/server/communication/AtmospherePushConnectionTest.java b/server/src/test/java/com/vaadin/server/communication/AtmospherePushConnectionTest.java
index d377496e19..49e32ebeec 100644
--- a/server/src/test/java/com/vaadin/server/communication/AtmospherePushConnectionTest.java
+++ b/server/src/test/java/com/vaadin/server/communication/AtmospherePushConnectionTest.java
@@ -15,6 +15,8 @@
  */
 package com.vaadin.server.communication;
 
+import static org.junit.Assert.assertEquals;
+
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.ObjectInputStream;
@@ -22,7 +24,6 @@ import java.io.ObjectOutputStream;
 
 import org.atmosphere.cpr.AtmosphereResource;
 import org.easymock.EasyMock;
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.server.communication.AtmospherePushConnection.State;
@@ -39,7 +40,7 @@ public class AtmospherePushConnectionTest {
         AtmospherePushConnection connection = new AtmospherePushConnection(ui);
         connection.connect(resource);
 
-        Assert.assertEquals(State.CONNECTED, connection.getState());
+        assertEquals(State.CONNECTED, connection.getState());
 
         ByteArrayOutputStream baos = new ByteArrayOutputStream();
 
@@ -48,6 +49,6 @@ public class AtmospherePushConnectionTest {
         connection = (AtmospherePushConnection) new ObjectInputStream(
                 new ByteArrayInputStream(baos.toByteArray())).readObject();
 
-        Assert.assertEquals(State.DISCONNECTED, connection.getState());
+        assertEquals(State.DISCONNECTED, connection.getState());
     }
 }
diff --git a/server/src/test/java/com/vaadin/server/communication/MetadataWriterTest.java b/server/src/test/java/com/vaadin/server/communication/MetadataWriterTest.java
index 679598de91..04d85e80b7 100644
--- a/server/src/test/java/com/vaadin/server/communication/MetadataWriterTest.java
+++ b/server/src/test/java/com/vaadin/server/communication/MetadataWriterTest.java
@@ -15,13 +15,13 @@
  */
 package com.vaadin.server.communication;
 
+import static org.junit.Assert.assertEquals;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
 import java.io.IOException;
 import java.io.StringWriter;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.Mockito;
@@ -56,20 +56,19 @@ public class MetadataWriterTest {
     @Test
     public void writeAsyncTag() throws Exception {
         new MetadataWriter().write(ui, writer, false, true, messages);
-        Assert.assertEquals("{\"async\":true}", writer.getBuffer().toString());
+        assertEquals("{\"async\":true}", writer.getBuffer().toString());
     }
 
     @Test
     public void writeRepaintTag() throws Exception {
         new MetadataWriter().write(ui, writer, true, false, messages);
-        Assert.assertEquals("{\"repaintAll\":true}",
-                writer.getBuffer().toString());
+        assertEquals("{\"repaintAll\":true}", writer.getBuffer().toString());
     }
 
     @Test
     public void writeRepaintAndAsyncTag() throws Exception {
         new MetadataWriter().write(ui, writer, true, true, messages);
-        Assert.assertEquals("{\"repaintAll\":true, \"async\":true}",
+        assertEquals("{\"repaintAll\":true, \"async\":true}",
                 writer.getBuffer().toString());
     }
 
@@ -78,7 +77,7 @@ public class MetadataWriterTest {
         disableSessionExpirationMessages(messages);
 
         new MetadataWriter().write(ui, writer, false, false, messages);
-        Assert.assertEquals("{}", writer.getBuffer().toString());
+        assertEquals("{}", writer.getBuffer().toString());
     }
 
     @Test
@@ -89,8 +88,7 @@ public class MetadataWriterTest {
         disableSessionExpirationMessages(messages);
 
         new MetadataWriter().write(ui, writer, false, false, messages);
-        Assert.assertEquals(
-                "{\"timedRedirect\":{\"interval\":15,\"url\":\"\"}}",
+        assertEquals("{\"timedRedirect\":{\"interval\":15,\"url\":\"\"}}",
                 writer.getBuffer().toString());
     }
 
@@ -102,7 +100,7 @@ public class MetadataWriterTest {
         disableSessionExpirationMessages(messages);
 
         new MetadataWriter().write(ui, writer, false, true, messages);
-        Assert.assertEquals(
+        assertEquals(
                 "{\"async\":true,\"timedRedirect\":{\"interval\":15,\"url\":\"\"}}",
                 writer.getBuffer().toString());
     }
diff --git a/server/src/test/java/com/vaadin/server/communication/ServletUIInitHandlerTest.java b/server/src/test/java/com/vaadin/server/communication/ServletUIInitHandlerTest.java
index 6c61922307..6ded996687 100644
--- a/server/src/test/java/com/vaadin/server/communication/ServletUIInitHandlerTest.java
+++ b/server/src/test/java/com/vaadin/server/communication/ServletUIInitHandlerTest.java
@@ -15,6 +15,8 @@
  */
 package com.vaadin.server.communication;
 
+import static org.junit.Assert.assertEquals;
+
 import java.io.IOException;
 import java.util.Properties;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -24,7 +26,6 @@ import javax.servlet.ServletOutputStream;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
-import org.junit.Assert;
 import org.junit.Test;
 import org.mockito.Mockito;
 
@@ -145,9 +146,9 @@ public class ServletUIInitHandlerTest {
                     }
                 });
 
-        Assert.assertEquals(1, pre.getAndIncrement());
-        Assert.assertEquals(1, errorHandlerCalls.getAndIncrement());
-        Assert.assertEquals(mock.session, ui.getSession());
+        assertEquals(1, pre.getAndIncrement());
+        assertEquals(1, errorHandlerCalls.getAndIncrement());
+        assertEquals(mock.session, ui.getSession());
     }
 
     @Test
@@ -180,9 +181,9 @@ public class ServletUIInitHandlerTest {
                     }
                 });
 
-        Assert.assertEquals(1, pre.getAndIncrement());
+        assertEquals(1, pre.getAndIncrement());
         // Default error handler only logs the exception
-        Assert.assertEquals(mock.session, ui.getSession());
+        assertEquals(mock.session, ui.getSession());
     }
 
 }
diff --git a/server/src/test/java/com/vaadin/tests/components/TreeTest.java b/server/src/test/java/com/vaadin/tests/components/TreeTest.java
index 8fc5fc28b6..10094dc8f0 100644
--- a/server/src/test/java/com/vaadin/tests/components/TreeTest.java
+++ b/server/src/test/java/com/vaadin/tests/components/TreeTest.java
@@ -36,7 +36,7 @@ public class TreeTest {
         public void itemCollapse(CollapseEvent<String> event) {
             assertEquals("Source component was incorrect", tree,
                     event.getComponent());
-            Assert.assertFalse("Multiple collapse events", collapsed);
+            assertFalse("Multiple collapse events", collapsed);
             collapsed = true;
         }
 
@@ -44,7 +44,7 @@ public class TreeTest {
         public void itemExpand(ExpandEvent<String> event) {
             assertEquals("Source component was incorrect", tree,
                     event.getComponent());
-            Assert.assertFalse("Multiple expand events", expanded);
+            assertFalse("Multiple expand events", expanded);
             expanded = true;
         }
 
@@ -71,13 +71,13 @@ public class TreeTest {
         tree.addExpandListener(listener);
         tree.addCollapseListener(listener);
 
-        Assert.assertFalse(listener.isExpanded());
+        assertFalse(listener.isExpanded());
         tree.expand("Foo");
         assertTrue("Item not expanded", tree.isExpanded("Foo"));
         assertTrue("Expand event not fired", listener.isExpanded());
-        Assert.assertFalse(listener.isCollapsed());
+        assertFalse(listener.isCollapsed());
         tree.collapse("Foo");
-        Assert.assertFalse("Item not collapsed", tree.isExpanded("Foo"));
+        assertFalse("Item not collapsed", tree.isExpanded("Foo"));
         assertTrue("Collapse event not fired", listener.isCollapsed());
     }
 
diff --git a/server/src/test/java/com/vaadin/tests/components/grid/GridComponentRendererTest.java b/server/src/test/java/com/vaadin/tests/components/grid/GridComponentRendererTest.java
index d0b2b11dca..e8cfc63ec5 100644
--- a/server/src/test/java/com/vaadin/tests/components/grid/GridComponentRendererTest.java
+++ b/server/src/test/java/com/vaadin/tests/components/grid/GridComponentRendererTest.java
@@ -1,10 +1,12 @@
 package com.vaadin.tests.components.grid;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.Future;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -55,7 +57,7 @@ public class GridComponentRendererTest {
         generateDataForClient(true);
         dataProvider.refreshItem(PERSON);
         generateDataForClient(false);
-        Assert.assertNotNull("Old component should exist.", oldComponent);
+        assertNotNull("Old component should exist.", oldComponent);
     }
 
     @Test
@@ -63,26 +65,25 @@ public class GridComponentRendererTest {
         generateDataForClient(true);
         grid.select(PERSON);
         generateDataForClient(false);
-        Assert.assertNotNull("Old component should exist.", oldComponent);
+        assertNotNull("Old component should exist.", oldComponent);
     }
 
     @Test
     public void testComponentChangeOnDataProviderChange() {
         generateDataForClient(true);
         grid.setItems(PERSON);
-        Assert.assertEquals(
-                "Test component was not detached on DataProvider change.", null,
-                testComponent.getParent());
+        assertEquals("Test component was not detached on DataProvider change.",
+                null, testComponent.getParent());
     }
 
     private void generateDataForClient(boolean initial) {
         grid.getDataCommunicator().beforeClientResponse(initial);
         if (testComponent != null) {
-            Assert.assertEquals("New component was not attached.", grid,
+            assertEquals("New component was not attached.", grid,
                     testComponent.getParent());
         }
         if (oldComponent != null) {
-            Assert.assertEquals("Old component was not detached.", null,
+            assertEquals("Old component was not detached.", null,
                     oldComponent.getParent());
         }
     }
diff --git a/server/src/test/java/com/vaadin/tests/components/grid/GridMultiSelectionModelTest.java b/server/src/test/java/com/vaadin/tests/components/grid/GridMultiSelectionModelTest.java
index 3b107d6c9b..f6696155c2 100644
--- a/server/src/test/java/com/vaadin/tests/components/grid/GridMultiSelectionModelTest.java
+++ b/server/src/test/java/com/vaadin/tests/components/grid/GridMultiSelectionModelTest.java
@@ -3,6 +3,7 @@ package com.vaadin.tests.components.grid;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertTrue;
 
 import java.util.ArrayList;
@@ -19,7 +20,6 @@ import java.util.concurrent.atomic.AtomicReference;
 import java.util.stream.IntStream;
 
 import org.easymock.Capture;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.Mockito;
@@ -169,11 +169,11 @@ public class GridMultiSelectionModelTest {
 
         customGrid.getDataCommunicator().beforeClientResponse(true);
 
-        Assert.assertFalse("Item should have been updated as selected",
+        assertFalse("Item should have been updated as selected",
                 customModel.generatedData.get("Foo"));
-        Assert.assertFalse("Item should have been updated as NOT selected",
+        assertFalse("Item should have been updated as NOT selected",
                 customModel.generatedData.get("Bar"));
-        Assert.assertFalse("Item should have been updated as NOT selected",
+        assertFalse("Item should have been updated as NOT selected",
                 customModel.generatedData.get("Baz"));
 
         customModel.generatedData.clear();
@@ -181,11 +181,11 @@ public class GridMultiSelectionModelTest {
         customGrid.getSelectionModel().select("Foo");
         customGrid.getDataCommunicator().beforeClientResponse(false);
 
-        Assert.assertTrue("Item should have been updated as selected",
+        assertTrue("Item should have been updated as selected",
                 customModel.generatedData.get("Foo"));
-        Assert.assertFalse("Item should have NOT been updated",
+        assertFalse("Item should have NOT been updated",
                 customModel.generatedData.containsKey("Bar"));
-        Assert.assertFalse("Item should have NOT been updated",
+        assertFalse("Item should have NOT been updated",
                 customModel.generatedData.containsKey("Baz"));
 
         customModel.generatedData.clear();
@@ -193,11 +193,11 @@ public class GridMultiSelectionModelTest {
         customModel.updateSelection(asSet("Bar"), asSet("Foo"));
         customGrid.getDataCommunicator().beforeClientResponse(false);
 
-        Assert.assertFalse("Item should have been updated as NOT selected",
+        assertFalse("Item should have been updated as NOT selected",
                 customModel.generatedData.get("Foo"));
-        Assert.assertTrue("Item should have been updated as selected",
+        assertTrue("Item should have been updated as selected",
                 customModel.generatedData.get("Bar"));
-        Assert.assertFalse("Item should have NOT been updated",
+        assertFalse("Item should have NOT been updated",
                 customModel.generatedData.containsKey("Baz"));
 
         // switch to single to cause event
@@ -207,7 +207,7 @@ public class GridMultiSelectionModelTest {
 
         // changing selection model should trigger row updates, but the old
         // selection model is not triggered as it has been removed
-        Assert.assertTrue(customModel.generatedData.isEmpty()); // not triggered
+        assertTrue(customModel.generatedData.isEmpty()); // not triggered
     }
 
     @Test
@@ -217,22 +217,22 @@ public class GridMultiSelectionModelTest {
         gridWithStrings.setItems("Foo", "Bar", "Baz");
 
         GridSelectionModel<String> model = gridWithStrings.getSelectionModel();
-        Assert.assertFalse(model.isSelected("Foo"));
+        assertFalse(model.isSelected("Foo"));
 
         model.select("Foo");
-        Assert.assertTrue(model.isSelected("Foo"));
-        Assert.assertEquals(Optional.of("Foo"), model.getFirstSelectedItem());
+        assertTrue(model.isSelected("Foo"));
+        assertEquals(Optional.of("Foo"), model.getFirstSelectedItem());
 
         model.select("Bar");
-        Assert.assertTrue(model.isSelected("Foo"));
-        Assert.assertTrue(model.isSelected("Bar"));
-        Assert.assertEquals(Arrays.asList("Foo", "Bar"),
+        assertTrue(model.isSelected("Foo"));
+        assertTrue(model.isSelected("Bar"));
+        assertEquals(Arrays.asList("Foo", "Bar"),
                 new ArrayList<>(model.getSelectedItems()));
 
         model.deselect("Bar");
-        Assert.assertFalse(model.isSelected("Bar"));
-        Assert.assertTrue(model.getFirstSelectedItem().isPresent());
-        Assert.assertEquals(Arrays.asList("Foo"),
+        assertFalse(model.isSelected("Bar"));
+        assertTrue(model.getFirstSelectedItem().isPresent());
+        assertEquals(Arrays.asList("Foo"),
                 new ArrayList<>(model.getSelectedItems()));
     }
 
@@ -598,18 +598,18 @@ public class GridMultiSelectionModelTest {
         AtomicReference<MultiSelectionEvent<String>> event = new AtomicReference<>();
         Registration actualRegistration = model
                 .addMultiSelectionListener(evt -> {
-                    Assert.assertNull(event.get());
+                    assertNull(event.get());
                     event.set(evt);
                 });
-        Assert.assertSame(registration, actualRegistration);
+        assertSame(registration, actualRegistration);
 
         selectionListener.get().selectionChange(new MultiSelectionEvent<>(grid,
                 model.asMultiSelect(), Collections.emptySet(), true));
 
-        Assert.assertEquals(grid, event.get().getComponent());
-        Assert.assertEquals(new LinkedHashSet<>(Arrays.asList(value)),
+        assertEquals(grid, event.get().getComponent());
+        assertEquals(new LinkedHashSet<>(Arrays.asList(value)),
                 event.get().getValue());
-        Assert.assertTrue(event.get().isUserOriginated());
+        assertTrue(event.get().isUserOriginated());
     }
 
     @Test
@@ -622,32 +622,32 @@ public class GridMultiSelectionModelTest {
 
         ui.setContent(grid);
         // no items yet, default data provider is empty not in memory one
-        Assert.assertFalse(model.isSelectAllCheckBoxVisible());
-        Assert.assertEquals(SelectAllCheckBoxVisibility.DEFAULT,
+        assertFalse(model.isSelectAllCheckBoxVisible());
+        assertEquals(SelectAllCheckBoxVisibility.DEFAULT,
                 model.getSelectAllCheckBoxVisibility());
 
         grid.setItems("Foo", "Bar", "Baz");
 
         // in-memory container keeps default
-        Assert.assertTrue(model.isSelectAllCheckBoxVisible());
-        Assert.assertEquals(SelectAllCheckBoxVisibility.DEFAULT,
+        assertTrue(model.isSelectAllCheckBoxVisible());
+        assertEquals(SelectAllCheckBoxVisibility.DEFAULT,
                 model.getSelectAllCheckBoxVisibility());
 
         // change to explicit NO
         model.setSelectAllCheckBoxVisibility(
                 SelectAllCheckBoxVisibility.HIDDEN);
 
-        Assert.assertEquals(SelectAllCheckBoxVisibility.HIDDEN,
+        assertEquals(SelectAllCheckBoxVisibility.HIDDEN,
                 model.getSelectAllCheckBoxVisibility());
-        Assert.assertFalse(model.isSelectAllCheckBoxVisible());
+        assertFalse(model.isSelectAllCheckBoxVisible());
 
         // change to explicit YES
         model.setSelectAllCheckBoxVisibility(
                 SelectAllCheckBoxVisibility.VISIBLE);
 
-        Assert.assertEquals(SelectAllCheckBoxVisibility.VISIBLE,
+        assertEquals(SelectAllCheckBoxVisibility.VISIBLE,
                 model.getSelectAllCheckBoxVisibility());
-        Assert.assertTrue(model.isSelectAllCheckBoxVisible());
+        assertTrue(model.isSelectAllCheckBoxVisible());
     }
 
     @Test
@@ -660,8 +660,8 @@ public class GridMultiSelectionModelTest {
                 .setSelectionMode(SelectionMode.MULTI);
 
         // no items yet, default data provider is empty not in memory one
-        Assert.assertFalse(model.isSelectAllCheckBoxVisible());
-        Assert.assertEquals(SelectAllCheckBoxVisibility.DEFAULT,
+        assertFalse(model.isSelectAllCheckBoxVisible());
+        assertEquals(SelectAllCheckBoxVisibility.DEFAULT,
                 model.getSelectAllCheckBoxVisibility());
 
         grid.setDataProvider(
@@ -676,32 +676,32 @@ public class GridMultiSelectionModelTest {
                                 query -> 1000));
 
         // not in-memory -> checkbox is hidden
-        Assert.assertFalse(model.isSelectAllCheckBoxVisible());
-        Assert.assertEquals(SelectAllCheckBoxVisibility.DEFAULT,
+        assertFalse(model.isSelectAllCheckBoxVisible());
+        assertEquals(SelectAllCheckBoxVisibility.DEFAULT,
                 model.getSelectAllCheckBoxVisibility());
 
         // change to explicit YES
         model.setSelectAllCheckBoxVisibility(
                 SelectAllCheckBoxVisibility.VISIBLE);
 
-        Assert.assertEquals(SelectAllCheckBoxVisibility.VISIBLE,
+        assertEquals(SelectAllCheckBoxVisibility.VISIBLE,
                 model.getSelectAllCheckBoxVisibility());
-        Assert.assertTrue(model.isSelectAllCheckBoxVisible());
+        assertTrue(model.isSelectAllCheckBoxVisible());
 
         // change to explicit NO
         model.setSelectAllCheckBoxVisibility(
                 SelectAllCheckBoxVisibility.HIDDEN);
 
-        Assert.assertEquals(SelectAllCheckBoxVisibility.HIDDEN,
+        assertEquals(SelectAllCheckBoxVisibility.HIDDEN,
                 model.getSelectAllCheckBoxVisibility());
-        Assert.assertFalse(model.isSelectAllCheckBoxVisible());
+        assertFalse(model.isSelectAllCheckBoxVisible());
 
         // change back to depends on data provider
         model.setSelectAllCheckBoxVisibility(
                 SelectAllCheckBoxVisibility.DEFAULT);
 
-        Assert.assertFalse(model.isSelectAllCheckBoxVisible());
-        Assert.assertEquals(SelectAllCheckBoxVisibility.DEFAULT,
+        assertFalse(model.isSelectAllCheckBoxVisible());
+        assertEquals(SelectAllCheckBoxVisibility.DEFAULT,
                 model.getSelectAllCheckBoxVisibility());
 
     }
diff --git a/server/src/test/java/com/vaadin/tests/components/grid/GridNoSelectionModelTest.java b/server/src/test/java/com/vaadin/tests/components/grid/GridNoSelectionModelTest.java
index 4222b20d15..a33387e256 100644
--- a/server/src/test/java/com/vaadin/tests/components/grid/GridNoSelectionModelTest.java
+++ b/server/src/test/java/com/vaadin/tests/components/grid/GridNoSelectionModelTest.java
@@ -1,10 +1,12 @@
 package com.vaadin.tests.components.grid;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+
 import java.util.Arrays;
 import java.util.LinkedHashSet;
 import java.util.Optional;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -34,15 +36,15 @@ public class GridNoSelectionModelTest {
     public void select() {
         model.select(PERSON_A);
 
-        Assert.assertFalse(model.isSelected(PERSON_A));
-        Assert.assertEquals(0, model.getSelectedItems().size());
-        Assert.assertEquals(Optional.empty(), model.getFirstSelectedItem());
+        assertFalse(model.isSelected(PERSON_A));
+        assertEquals(0, model.getSelectedItems().size());
+        assertEquals(Optional.empty(), model.getFirstSelectedItem());
 
         model.select(PERSON_B);
 
-        Assert.assertFalse(model.isSelected(PERSON_B));
-        Assert.assertEquals(0, model.getSelectedItems().size());
-        Assert.assertEquals(Optional.empty(), model.getFirstSelectedItem());
+        assertFalse(model.isSelected(PERSON_B));
+        assertEquals(0, model.getSelectedItems().size());
+        assertEquals(Optional.empty(), model.getFirstSelectedItem());
     }
 
     @Test
@@ -50,7 +52,7 @@ public class GridNoSelectionModelTest {
         grid.setSelectionMode(SelectionMode.SINGLE);
 
         grid.getSelectionModel().select(PERSON_B);
-        Assert.assertEquals(PERSON_B,
+        assertEquals(PERSON_B,
                 grid.getSelectionModel().getFirstSelectedItem().get());
     }
 
@@ -59,7 +61,7 @@ public class GridNoSelectionModelTest {
         grid.setSelectionMode(SelectionMode.MULTI);
 
         grid.getSelectionModel().select(PERSON_B);
-        Assert.assertEquals(new LinkedHashSet<>(Arrays.asList(PERSON_B)),
+        assertEquals(new LinkedHashSet<>(Arrays.asList(PERSON_B)),
                 grid.getSelectionModel().getSelectedItems());
     }
 
diff --git a/server/src/test/java/com/vaadin/tests/components/grid/GridNullValueSort.java b/server/src/test/java/com/vaadin/tests/components/grid/GridNullValueSort.java
index c68cb2901c..b3040f8725 100644
--- a/server/src/test/java/com/vaadin/tests/components/grid/GridNullValueSort.java
+++ b/server/src/test/java/com/vaadin/tests/components/grid/GridNullValueSort.java
@@ -1,10 +1,11 @@
 package com.vaadin.tests.components.grid;
 
+import static org.junit.Assert.assertEquals;
+
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -148,7 +149,7 @@ public class GridNullValueSort {
                 .createSortingComparator();
         List<Integer> data = new ArrayList<>(source);
         data.sort(sortingComparator);
-        Assert.assertEquals(expected, data);
+        assertEquals(expected, data);
     }
 
 }
diff --git a/server/src/test/java/com/vaadin/tests/components/grid/GridSelectionModeTest.java b/server/src/test/java/com/vaadin/tests/components/grid/GridSelectionModeTest.java
index e9515be789..c8ca4cf791 100644
--- a/server/src/test/java/com/vaadin/tests/components/grid/GridSelectionModeTest.java
+++ b/server/src/test/java/com/vaadin/tests/components/grid/GridSelectionModeTest.java
@@ -1,6 +1,7 @@
 package com.vaadin.tests.components.grid;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+
 import org.junit.Before;
 import org.junit.Test;
 
@@ -22,22 +23,22 @@ public class GridSelectionModeTest {
 
     @Test
     public void testSelectionModes() {
-        Assert.assertEquals(SingleSelectionModelImpl.class,
+        assertEquals(SingleSelectionModelImpl.class,
                 grid.getSelectionModel().getClass());
 
-        Assert.assertEquals(MultiSelectionModelImpl.class,
+        assertEquals(MultiSelectionModelImpl.class,
                 grid.setSelectionMode(SelectionMode.MULTI).getClass());
-        Assert.assertEquals(MultiSelectionModelImpl.class,
+        assertEquals(MultiSelectionModelImpl.class,
                 grid.getSelectionModel().getClass());
 
-        Assert.assertEquals(NoSelectionModel.class,
+        assertEquals(NoSelectionModel.class,
                 grid.setSelectionMode(SelectionMode.NONE).getClass());
-        Assert.assertEquals(NoSelectionModel.class,
+        assertEquals(NoSelectionModel.class,
                 grid.getSelectionModel().getClass());
 
-        Assert.assertEquals(SingleSelectionModelImpl.class,
+        assertEquals(SingleSelectionModelImpl.class,
                 grid.setSelectionMode(SelectionMode.SINGLE).getClass());
-        Assert.assertEquals(SingleSelectionModelImpl.class,
+        assertEquals(SingleSelectionModelImpl.class,
                 grid.getSelectionModel().getClass());
     }
 
diff --git a/server/src/test/java/com/vaadin/tests/components/grid/GridSingleSelectionModelTest.java b/server/src/test/java/com/vaadin/tests/components/grid/GridSingleSelectionModelTest.java
index ce4da636d0..5791e2bc9d 100644
--- a/server/src/test/java/com/vaadin/tests/components/grid/GridSingleSelectionModelTest.java
+++ b/server/src/test/java/com/vaadin/tests/components/grid/GridSingleSelectionModelTest.java
@@ -2,6 +2,8 @@ package com.vaadin.tests.components.grid;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertTrue;
 
 import java.util.ArrayList;
@@ -12,7 +14,6 @@ import java.util.Map;
 import java.util.Optional;
 import java.util.concurrent.atomic.AtomicReference;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.Mockito;
@@ -127,11 +128,11 @@ public class GridSingleSelectionModelTest {
 
         customGrid.getDataCommunicator().beforeClientResponse(true);
 
-        Assert.assertFalse("Item should have been updated as selected",
+        assertFalse("Item should have been updated as selected",
                 customModel.generatedData.get("Foo"));
-        Assert.assertFalse("Item should have been updated as NOT selected",
+        assertFalse("Item should have been updated as NOT selected",
                 customModel.generatedData.get("Bar"));
-        Assert.assertFalse("Item should have been updated as NOT selected",
+        assertFalse("Item should have been updated as NOT selected",
                 customModel.generatedData.get("Baz"));
 
         customModel.generatedData.clear();
@@ -139,11 +140,11 @@ public class GridSingleSelectionModelTest {
         customGrid.getSelectionModel().select("Foo");
         customGrid.getDataCommunicator().beforeClientResponse(false);
 
-        Assert.assertTrue("Item should have been updated as selected",
+        assertTrue("Item should have been updated as selected",
                 customModel.generatedData.get("Foo"));
-        Assert.assertFalse("Item should have NOT been updated",
+        assertFalse("Item should have NOT been updated",
                 customModel.generatedData.containsKey("Bar"));
-        Assert.assertFalse("Item should have NOT been updated",
+        assertFalse("Item should have NOT been updated",
                 customModel.generatedData.containsKey("Baz"));
 
         // switch to another selection model to cause event
@@ -154,11 +155,11 @@ public class GridSingleSelectionModelTest {
         // since the selection model has been removed, it is no longer a data
         // generator for the data communicator, would need to verify somehow
         // that row is not marked as selected anymore ? (done in UI tests)
-        Assert.assertTrue(customModel.generatedData.isEmpty()); // at least
-                                                                // removed
-                                                                // selection
-                                                                // model is not
-                                                                // triggered
+        assertTrue(customModel.generatedData.isEmpty()); // at least
+                                                         // removed
+                                                         // selection
+                                                         // model is not
+                                                         // triggered
     }
 
     @Test
@@ -167,19 +168,19 @@ public class GridSingleSelectionModelTest {
         gridWithStrings.setItems("Foo", "Bar", "Baz");
 
         GridSelectionModel<String> model = gridWithStrings.getSelectionModel();
-        Assert.assertFalse(model.isSelected("Foo"));
+        assertFalse(model.isSelected("Foo"));
 
         model.select("Foo");
-        Assert.assertTrue(model.isSelected("Foo"));
-        Assert.assertEquals(Optional.of("Foo"), model.getFirstSelectedItem());
+        assertTrue(model.isSelected("Foo"));
+        assertEquals(Optional.of("Foo"), model.getFirstSelectedItem());
 
         model.select("Bar");
-        Assert.assertFalse(model.isSelected("Foo"));
-        Assert.assertTrue(model.isSelected("Bar"));
+        assertFalse(model.isSelected("Foo"));
+        assertTrue(model.isSelected("Bar"));
 
         model.deselect("Bar");
-        Assert.assertFalse(model.isSelected("Bar"));
-        Assert.assertFalse(model.getFirstSelectedItem().isPresent());
+        assertFalse(model.isSelected("Bar"));
+        assertFalse(model.getFirstSelectedItem().isPresent());
     }
 
     @Test
@@ -271,21 +272,21 @@ public class GridSingleSelectionModelTest {
     public void getSelectedItem() {
         selectionModel.setSelectedItem(PERSON_B);
 
-        Assert.assertEquals(PERSON_B, selectionModel.getSelectedItem().get());
+        assertEquals(PERSON_B, selectionModel.getSelectedItem().get());
 
         selectionModel.deselect(PERSON_B);
-        Assert.assertFalse(selectionModel.getSelectedItem().isPresent());
+        assertFalse(selectionModel.getSelectedItem().isPresent());
     }
 
     @Test
     public void select_deselect_getSelectedItem() {
         selectionModel.select(PERSON_C);
 
-        Assert.assertEquals(PERSON_C, selectionModel.getSelectedItem().get());
+        assertEquals(PERSON_C, selectionModel.getSelectedItem().get());
 
         selectionModel.deselect(PERSON_C);
 
-        Assert.assertFalse(selectionModel.getSelectedItem().isPresent());
+        assertFalse(selectionModel.getSelectedItem().isPresent());
     }
 
     @SuppressWarnings({ "serial" })
@@ -313,18 +314,18 @@ public class GridSingleSelectionModelTest {
         AtomicReference<ValueChangeEvent<?>> event = new AtomicReference<>();
         Registration actualRegistration = select
                 .addSingleSelectionListener(evt -> {
-                    Assert.assertNull(event.get());
+                    assertNull(event.get());
                     event.set(evt);
                 });
-        Assert.assertSame(registration, actualRegistration);
+        assertSame(registration, actualRegistration);
 
         selectionListener.get().selectionChange(new SingleSelectionEvent<>(grid,
                 select.asSingleSelect(), null, true));
 
-        Assert.assertEquals(grid, event.get().getComponent());
-        Assert.assertEquals(value, event.get().getValue());
-        Assert.assertEquals(null, event.get().getOldValue());
-        Assert.assertTrue(event.get().isUserOriginated());
+        assertEquals(grid, event.get().getComponent());
+        assertEquals(value, event.get().getValue());
+        assertEquals(null, event.get().getOldValue());
+        assertTrue(event.get().isUserOriginated());
     }
 
 }
diff --git a/server/src/test/java/com/vaadin/tests/components/grid/GridValueProvider.java b/server/src/test/java/com/vaadin/tests/components/grid/GridValueProvider.java
index 27ba971127..6b3d85900d 100644
--- a/server/src/test/java/com/vaadin/tests/components/grid/GridValueProvider.java
+++ b/server/src/test/java/com/vaadin/tests/components/grid/GridValueProvider.java
@@ -15,11 +15,13 @@
  */
 package com.vaadin.tests.components.grid;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertSame;
+
 import java.util.List;
 import java.util.Locale;
 import java.util.stream.Collectors;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.data.provider.DataProvider;
@@ -39,7 +41,7 @@ public class GridValueProvider {
                 person -> person.getFirstName() + " " + person.getLastName());
         Person person = new Person("first", "last", "email", 123, Sex.UNKNOWN,
                 null);
-        Assert.assertEquals("first last", col.getValueProvider().apply(person));
+        assertEquals("first last", col.getValueProvider().apply(person));
     }
 
     @Test
@@ -49,7 +51,7 @@ public class GridValueProvider {
                 .getColumn("email");
         Person person = new Person("first", "last", "eeemaaail", 123,
                 Sex.UNKNOWN, null);
-        Assert.assertEquals("eeemaaail", col.getValueProvider().apply(person));
+        assertEquals("eeemaaail", col.getValueProvider().apply(person));
 
     }
 
@@ -71,7 +73,7 @@ public class GridValueProvider {
 
         List<Person> queryPersons = persons.fetch(new Query<>())
                 .collect(Collectors.toList());
-        Assert.assertEquals(1, queryPersons.size());
-        Assert.assertSame(upperCasePerson, queryPersons.get(0));
+        assertEquals(1, queryPersons.size());
+        assertSame(upperCasePerson, queryPersons.get(0));
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/components/menubar/MenuBarDeclarativeTest.java b/server/src/test/java/com/vaadin/tests/components/menubar/MenuBarDeclarativeTest.java
index e0706d9575..5a67d2bcce 100644
--- a/server/src/test/java/com/vaadin/tests/components/menubar/MenuBarDeclarativeTest.java
+++ b/server/src/test/java/com/vaadin/tests/components/menubar/MenuBarDeclarativeTest.java
@@ -15,10 +15,12 @@
  */
 package com.vaadin.tests.components.menubar;
 
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.fail;
+
 import java.io.IOException;
 import java.util.List;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.server.ExternalResource;
@@ -140,8 +142,8 @@ public class MenuBarDeclarativeTest extends DeclarativeTestBase<MenuBar> {
 
         List<MenuItem> expectedMenuItems = expected.getItems();
         List<MenuItem> actualMenuItems = result.getItems();
-        Assert.assertEquals("Different amount of menu items",
-                expectedMenuItems.size(), actualMenuItems.size());
+        assertEquals("Different amount of menu items", expectedMenuItems.size(),
+                actualMenuItems.size());
 
         for (int i = 0; i < expectedMenuItems.size(); ++i) {
             compareMenus(expectedMenuItems.get(i), actualMenuItems.get(i));
@@ -153,38 +155,37 @@ public class MenuBarDeclarativeTest extends DeclarativeTestBase<MenuBar> {
     private void compareMenus(MenuItem expected, MenuItem actual) {
         String baseError = "Error Comparing MenuItem " + expected.getText()
                 + ": ";
-        Assert.assertEquals(baseError + "Visibile", expected.isVisible(),
+        assertEquals(baseError + "Visibile", expected.isVisible(),
                 actual.isVisible());
-        Assert.assertEquals(baseError + "Checkable", expected.isCheckable(),
+        assertEquals(baseError + "Checkable", expected.isCheckable(),
                 actual.isCheckable());
-        Assert.assertEquals(baseError + "Checked", expected.isChecked(),
+        assertEquals(baseError + "Checked", expected.isChecked(),
                 actual.isChecked());
-        Assert.assertEquals(baseError + "Separator", expected.isSeparator(),
+        assertEquals(baseError + "Separator", expected.isSeparator(),
                 actual.isSeparator());
-        Assert.assertEquals(baseError + "Enabled", expected.isEnabled(),
+        assertEquals(baseError + "Enabled", expected.isEnabled(),
                 actual.isEnabled());
 
-        Assert.assertEquals(baseError + "Text", expected.getText(),
-                actual.getText());
-        Assert.assertEquals(baseError + "Description",
-                expected.getDescription(), actual.getDescription());
-        Assert.assertEquals(baseError + "Style Name", expected.getStyleName(),
+        assertEquals(baseError + "Text", expected.getText(), actual.getText());
+        assertEquals(baseError + "Description", expected.getDescription(),
+                actual.getDescription());
+        assertEquals(baseError + "Style Name", expected.getStyleName(),
                 actual.getStyleName());
 
         if (expected.getIcon() != null) {
-            Assert.assertNotNull(baseError + "Icon was null", actual.getIcon());
+            assertNotNull(baseError + "Icon was null", actual.getIcon());
         } else {
             if (actual.getIcon() != null) {
-                Assert.fail(baseError + "Icon should've been null");
+                fail(baseError + "Icon should've been null");
             }
         }
 
-        Assert.assertEquals(baseError + "Has Children", expected.hasChildren(),
+        assertEquals(baseError + "Has Children", expected.hasChildren(),
                 actual.hasChildren());
         if (expected.hasChildren()) {
             List<MenuItem> children = expected.getChildren();
             List<MenuItem> actualChildren = actual.getChildren();
-            Assert.assertEquals(baseError + "Child count", children.size(),
+            assertEquals(baseError + "Child count", children.size(),
                     actualChildren.size());
             for (int i = 0; i < children.size(); ++i) {
                 compareMenus(children.get(i), actualChildren.get(i));
diff --git a/server/src/test/java/com/vaadin/tests/components/treegrid/TreeGridTest.java b/server/src/test/java/com/vaadin/tests/components/treegrid/TreeGridTest.java
index 1876d8de35..d7abcd7301 100644
--- a/server/src/test/java/com/vaadin/tests/components/treegrid/TreeGridTest.java
+++ b/server/src/test/java/com/vaadin/tests/components/treegrid/TreeGridTest.java
@@ -1,6 +1,9 @@
 package com.vaadin.tests.components.treegrid;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import org.junit.Test;
 
 import com.vaadin.data.TreeData;
@@ -35,16 +38,16 @@ public class TreeGridTest {
         treeGrid.addCollapseListener(e -> collapseEventFired = true);
 
         // Test expand event
-        Assert.assertFalse(expandEventFired);
+        assertFalse(expandEventFired);
         treeGrid.expand("Foo");
-        Assert.assertTrue("Item not expanded", treeGrid.isExpanded("Foo"));
-        Assert.assertTrue("Expand event not fired", expandEventFired);
+        assertTrue("Item not expanded", treeGrid.isExpanded("Foo"));
+        assertTrue("Expand event not fired", expandEventFired);
 
         // Test collapse event
-        Assert.assertFalse(collapseEventFired);
+        assertFalse(collapseEventFired);
         treeGrid.collapse("Foo");
-        Assert.assertFalse("Item not collapsed", treeGrid.isExpanded("Foo"));
-        Assert.assertTrue("Collapse event not fired", collapseEventFired);
+        assertFalse("Item not collapsed", treeGrid.isExpanded("Foo"));
+        assertTrue("Collapse event not fired", collapseEventFired);
     }
 
     @Test
@@ -52,8 +55,8 @@ public class TreeGridTest {
         Column<String, String> column = treeGrid.addColumn(Object::toString)
                 .setId("foo");
         treeGrid.setHierarchyColumn("foo");
-        Assert.assertEquals("Hierarchy column was not correctly returned",
-                column, treeGrid.getHierarchyColumn());
+        assertEquals("Hierarchy column was not correctly returned", column,
+                treeGrid.getHierarchyColumn());
     }
 
 }
diff --git a/server/src/test/java/com/vaadin/tests/data/converter/AbstractConverterTest.java b/server/src/test/java/com/vaadin/tests/data/converter/AbstractConverterTest.java
index ead81250bf..797a4bc96f 100644
--- a/server/src/test/java/com/vaadin/tests/data/converter/AbstractConverterTest.java
+++ b/server/src/test/java/com/vaadin/tests/data/converter/AbstractConverterTest.java
@@ -1,6 +1,10 @@
 package com.vaadin.tests.data.converter;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
 import org.junit.Test;
 
 import com.vaadin.data.Converter;
@@ -23,17 +27,17 @@ public abstract class AbstractConverterTest {
 
     protected <T> void assertValue(String assertMessage, T expectedValue,
             Result<?> result) {
-        Assert.assertNotNull("Result should never be null", result);
-        Assert.assertFalse("Result is not ok", result.isError());
-        Assert.assertEquals(expectedValue,
+        assertNotNull("Result should never be null", result);
+        assertFalse("Result is not ok", result.isError());
+        assertEquals(expectedValue,
                 result.getOrThrow(message -> new AssertionError(
                         assertMessage != null ? assertMessage : message)));
     }
 
     protected void assertError(String expectedResultMessage, Result<?> result) {
-        Assert.assertNotNull("Result should never be null", result);
-        Assert.assertTrue("Result should be an error", result.isError());
-        Assert.assertEquals(expectedResultMessage, result.getMessage().get());
+        assertNotNull("Result should never be null", result);
+        assertTrue("Result should be an error", result.isError());
+        assertEquals(expectedResultMessage, result.getMessage().get());
     }
 
     protected String getErrorMessage() {
diff --git a/server/src/test/java/com/vaadin/tests/data/converter/AbstractStringConverterTest.java b/server/src/test/java/com/vaadin/tests/data/converter/AbstractStringConverterTest.java
index 123ef80de2..459702beaf 100644
--- a/server/src/test/java/com/vaadin/tests/data/converter/AbstractStringConverterTest.java
+++ b/server/src/test/java/com/vaadin/tests/data/converter/AbstractStringConverterTest.java
@@ -1,6 +1,8 @@
 package com.vaadin.tests.data.converter;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
 import org.junit.Test;
 
 import com.vaadin.data.Converter;
@@ -23,8 +25,8 @@ public abstract class AbstractStringConverterTest
     public void testErrorMessage() {
         Result<?> result = getConverter().convertToModel("abc",
                 new ValueContext());
-        Assert.assertTrue(result.isError());
-        Assert.assertEquals(getErrorMessage(), result.getMessage().get());
+        assertTrue(result.isError());
+        assertEquals(getErrorMessage(), result.getMessage().get());
     }
 
     @Override
diff --git a/server/src/test/java/com/vaadin/tests/data/converter/ConverterTest.java b/server/src/test/java/com/vaadin/tests/data/converter/ConverterTest.java
index 3ba3c28882..3c31fddd7e 100644
--- a/server/src/test/java/com/vaadin/tests/data/converter/ConverterTest.java
+++ b/server/src/test/java/com/vaadin/tests/data/converter/ConverterTest.java
@@ -1,6 +1,7 @@
 package com.vaadin.tests.data.converter;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+
 import org.junit.Test;
 
 import com.vaadin.data.Converter;
@@ -26,9 +27,9 @@ public class ConverterTest {
 
     @Test
     public void basicConversion() {
-        Assert.assertEquals("presentation-123",
+        assertEquals("presentation-123",
                 converter.convertToPresentation("123", new ValueContext()));
-        Assert.assertEquals("123",
+        assertEquals("123",
                 converter.convertToModel("presentation-123", new ValueContext())
                         .getOrThrow(msg -> new AssertionError(msg)));
     }
diff --git a/server/src/test/java/com/vaadin/tests/data/converter/LocalDateTimeToDateConverterTest.java b/server/src/test/java/com/vaadin/tests/data/converter/LocalDateTimeToDateConverterTest.java
index fdad1391f5..eaa66fd526 100644
--- a/server/src/test/java/com/vaadin/tests/data/converter/LocalDateTimeToDateConverterTest.java
+++ b/server/src/test/java/com/vaadin/tests/data/converter/LocalDateTimeToDateConverterTest.java
@@ -15,13 +15,14 @@
  */
 package com.vaadin.tests.data.converter;
 
+import static org.junit.Assert.assertEquals;
+
 import java.time.LocalDateTime;
 import java.time.ZoneOffset;
 import java.util.Calendar;
 import java.util.Date;
 import java.util.TimeZone;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.data.Binder;
@@ -56,7 +57,7 @@ public class LocalDateTimeToDateConverterTest extends AbstractConverterTest {
 
     @Test
     public void testToPresentation() {
-        Assert.assertEquals(LOCAL_DATE,
+        assertEquals(LOCAL_DATE,
                 getConverter().convertToPresentation(DATE, new ValueContext()));
     }
 
@@ -73,7 +74,7 @@ public class LocalDateTimeToDateConverterTest extends AbstractConverterTest {
         BeanWithDate bean = new BeanWithDate();
         binder.writeBean(bean);
 
-        Assert.assertEquals(DATE, bean.getDate());
+        assertEquals(DATE, bean.getDate());
     }
 
     public static class BeanWithDate {
diff --git a/server/src/test/java/com/vaadin/tests/data/converter/LocalDateToDateConverterTest.java b/server/src/test/java/com/vaadin/tests/data/converter/LocalDateToDateConverterTest.java
index 9517ad783b..c1466ab94c 100644
--- a/server/src/test/java/com/vaadin/tests/data/converter/LocalDateToDateConverterTest.java
+++ b/server/src/test/java/com/vaadin/tests/data/converter/LocalDateToDateConverterTest.java
@@ -15,13 +15,14 @@
  */
 package com.vaadin.tests.data.converter;
 
+import static org.junit.Assert.assertEquals;
+
 import java.time.LocalDate;
 import java.time.ZoneId;
 import java.util.Calendar;
 import java.util.Date;
 import java.util.TimeZone;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.data.Binder;
@@ -57,7 +58,7 @@ public class LocalDateToDateConverterTest extends AbstractConverterTest {
 
     @Test
     public void testToPresentation() {
-        Assert.assertEquals(LOCAL_DATE,
+        assertEquals(LOCAL_DATE,
                 getConverter().convertToPresentation(DATE, new ValueContext()));
     }
 
@@ -74,7 +75,7 @@ public class LocalDateToDateConverterTest extends AbstractConverterTest {
         BeanWithDate bean = new BeanWithDate();
         binder.writeBean(bean);
 
-        Assert.assertEquals(DATE, bean.getDate());
+        assertEquals(DATE, bean.getDate());
     }
 
     public static class BeanWithDate {
diff --git a/server/src/test/java/com/vaadin/tests/data/converter/StringToBigDecimalConverterTest.java b/server/src/test/java/com/vaadin/tests/data/converter/StringToBigDecimalConverterTest.java
index 60dad91e61..54363e768f 100644
--- a/server/src/test/java/com/vaadin/tests/data/converter/StringToBigDecimalConverterTest.java
+++ b/server/src/test/java/com/vaadin/tests/data/converter/StringToBigDecimalConverterTest.java
@@ -15,10 +15,11 @@
  */
 package com.vaadin.tests.data.converter;
 
+import static org.junit.Assert.assertEquals;
+
 import java.math.BigDecimal;
 import java.util.Locale;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.data.Result;
@@ -48,7 +49,7 @@ public class StringToBigDecimalConverterTest
 
         String converted = getConverter().convertToPresentation(bd,
                 new ValueContext(Locale.GERMAN));
-        Assert.assertEquals(expected, converted);
+        assertEquals(expected, converted);
     }
 
     @Test
@@ -58,7 +59,7 @@ public class StringToBigDecimalConverterTest
 
         assertValue(BigDecimal.ZERO,
                 converter.convertToModel("", new ValueContext()));
-        Assert.assertEquals("0", converter
-                .convertToPresentation(BigDecimal.ZERO, new ValueContext()));
+        assertEquals("0", converter.convertToPresentation(BigDecimal.ZERO,
+                new ValueContext()));
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/data/converter/StringToBigIntegerConverterTest.java b/server/src/test/java/com/vaadin/tests/data/converter/StringToBigIntegerConverterTest.java
index 28abe19224..132feee20d 100644
--- a/server/src/test/java/com/vaadin/tests/data/converter/StringToBigIntegerConverterTest.java
+++ b/server/src/test/java/com/vaadin/tests/data/converter/StringToBigIntegerConverterTest.java
@@ -15,10 +15,11 @@
  */
 package com.vaadin.tests.data.converter;
 
+import static org.junit.Assert.assertEquals;
+
 import java.math.BigInteger;
 import java.util.Locale;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.data.Result;
@@ -50,8 +51,7 @@ public class StringToBigIntegerConverterTest
 
         String converted = getConverter().convertToPresentation(bd,
                 new ValueContext(Locale.GERMAN));
-        Assert.assertEquals(
-                "Value with specific locale was converted incorrectly",
+        assertEquals("Value with specific locale was converted incorrectly",
                 expected, converted);
     }
 
@@ -62,8 +62,8 @@ public class StringToBigIntegerConverterTest
 
         assertValue(BigInteger.ZERO,
                 converter.convertToModel("", new ValueContext()));
-        Assert.assertEquals("0", converter
-                .convertToPresentation(BigInteger.ZERO, new ValueContext()));
+        assertEquals("0", converter.convertToPresentation(BigInteger.ZERO,
+                new ValueContext()));
     }
 
 }
diff --git a/server/src/test/java/com/vaadin/tests/data/converter/StringToBooleanConverterTest.java b/server/src/test/java/com/vaadin/tests/data/converter/StringToBooleanConverterTest.java
index 5c265fe31c..f1ab5f19f6 100644
--- a/server/src/test/java/com/vaadin/tests/data/converter/StringToBooleanConverterTest.java
+++ b/server/src/test/java/com/vaadin/tests/data/converter/StringToBooleanConverterTest.java
@@ -1,10 +1,11 @@
 package com.vaadin.tests.data.converter;
 
+import static org.junit.Assert.assertEquals;
+
 import java.text.SimpleDateFormat;
 import java.util.Date;
 import java.util.Locale;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.data.ValueContext;
@@ -57,9 +58,9 @@ public class StringToBooleanConverterTest extends AbstractStringConverterTest {
         assertValue(false,
                 yesNoConverter.convertToModel("no", new ValueContext()));
 
-        Assert.assertEquals("yes",
+        assertEquals("yes",
                 yesNoConverter.convertToPresentation(true, new ValueContext()));
-        Assert.assertEquals("no", yesNoConverter.convertToPresentation(false,
+        assertEquals("no", yesNoConverter.convertToPresentation(false,
                 new ValueContext()));
     }
 
@@ -70,23 +71,22 @@ public class StringToBooleanConverterTest extends AbstractStringConverterTest {
         assertValue(false, emptyTrueConverter.convertToModel("ABSENT",
                 new ValueContext()));
 
-        Assert.assertEquals("", emptyTrueConverter.convertToPresentation(true,
+        assertEquals("", emptyTrueConverter.convertToPresentation(true,
+                new ValueContext()));
+        assertEquals("ABSENT", emptyTrueConverter.convertToPresentation(false,
                 new ValueContext()));
-        Assert.assertEquals("ABSENT", emptyTrueConverter
-                .convertToPresentation(false, new ValueContext()));
     }
 
     @Test
     public void testLocale() {
-        Assert.assertEquals("May 18, 2033", localeConverter
-                .convertToPresentation(true, new ValueContext(Locale.US)));
-        Assert.assertEquals("January 24, 2065", localeConverter
+        assertEquals("May 18, 2033", localeConverter.convertToPresentation(true,
+                new ValueContext(Locale.US)));
+        assertEquals("January 24, 2065", localeConverter
                 .convertToPresentation(false, new ValueContext(Locale.US)));
 
-        Assert.assertEquals("18. Mai 2033", localeConverter
-                .convertToPresentation(true, new ValueContext(Locale.GERMANY)));
-        Assert.assertEquals("24. Januar 2065",
-                localeConverter.convertToPresentation(false,
-                        new ValueContext(Locale.GERMANY)));
+        assertEquals("18. Mai 2033", localeConverter.convertToPresentation(true,
+                new ValueContext(Locale.GERMANY)));
+        assertEquals("24. Januar 2065", localeConverter.convertToPresentation(
+                false, new ValueContext(Locale.GERMANY)));
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/data/converter/StringToDoubleConverterTest.java b/server/src/test/java/com/vaadin/tests/data/converter/StringToDoubleConverterTest.java
index 2dda3d7dbf..43dab81203 100644
--- a/server/src/test/java/com/vaadin/tests/data/converter/StringToDoubleConverterTest.java
+++ b/server/src/test/java/com/vaadin/tests/data/converter/StringToDoubleConverterTest.java
@@ -1,6 +1,8 @@
 package com.vaadin.tests.data.converter;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
 import org.junit.Test;
 
 import com.vaadin.data.Result;
@@ -31,8 +33,8 @@ public class StringToDoubleConverterTest extends AbstractConverterTest {
     public void testErrorMessage() {
         Result<Double> result = getConverter().convertToModel("abc",
                 new ValueContext());
-        Assert.assertTrue(result.isError());
-        Assert.assertEquals("Failed", result.getMessage().get());
+        assertTrue(result.isError());
+        assertEquals("Failed", result.getMessage().get());
     }
 
     @Test
@@ -41,7 +43,7 @@ public class StringToDoubleConverterTest extends AbstractConverterTest {
                 getErrorMessage());
 
         assertValue(0.0, converter.convertToModel("", new ValueContext()));
-        Assert.assertEquals("0",
+        assertEquals("0",
                 converter.convertToPresentation(0.0, new ValueContext()));
     }
 
diff --git a/server/src/test/java/com/vaadin/tests/data/converter/StringToFloatConverterTest.java b/server/src/test/java/com/vaadin/tests/data/converter/StringToFloatConverterTest.java
index 2601ae2cd4..6cac48df97 100644
--- a/server/src/test/java/com/vaadin/tests/data/converter/StringToFloatConverterTest.java
+++ b/server/src/test/java/com/vaadin/tests/data/converter/StringToFloatConverterTest.java
@@ -1,6 +1,7 @@
 package com.vaadin.tests.data.converter;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+
 import org.junit.Test;
 
 import com.vaadin.data.ValueContext;
@@ -40,7 +41,7 @@ public class StringToFloatConverterTest extends AbstractStringConverterTest {
 
         assertValue((float) 0.0,
                 converter.convertToModel("", new ValueContext()));
-        Assert.assertEquals("0", converter.convertToPresentation((float) 0.0,
+        assertEquals("0", converter.convertToPresentation((float) 0.0,
                 new ValueContext()));
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/data/converter/StringToIntegerConverterTest.java b/server/src/test/java/com/vaadin/tests/data/converter/StringToIntegerConverterTest.java
index 8ea4e7a558..db050233cf 100644
--- a/server/src/test/java/com/vaadin/tests/data/converter/StringToIntegerConverterTest.java
+++ b/server/src/test/java/com/vaadin/tests/data/converter/StringToIntegerConverterTest.java
@@ -1,6 +1,9 @@
 package com.vaadin.tests.data.converter;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import org.junit.Test;
 
 import com.vaadin.data.Result;
@@ -22,9 +25,8 @@ public class StringToIntegerConverterTest extends AbstractConverterTest {
 
     @Test
     public void testValueOutOfRange() {
-        Double[] values = { Integer.MAX_VALUE * 2.0,
-                Integer.MIN_VALUE * 2.0, Long.MAX_VALUE * 2.0,
-                Long.MIN_VALUE * 2.0 };
+        Double[] values = { Integer.MAX_VALUE * 2.0, Integer.MIN_VALUE * 2.0,
+                Long.MAX_VALUE * 2.0, Long.MIN_VALUE * 2.0 };
 
         boolean accepted = false;
         for (Number value : values) {
@@ -35,7 +37,7 @@ public class StringToIntegerConverterTest extends AbstractConverterTest {
                 accepted = true;
             }
         }
-        Assert.assertFalse("Accepted value outside range of int", accepted);
+        assertFalse("Accepted value outside range of int", accepted);
     }
 
     @Test
@@ -48,8 +50,8 @@ public class StringToIntegerConverterTest extends AbstractConverterTest {
     public void testErrorMessage() {
         Result<Integer> result = getConverter().convertToModel("abc",
                 new ValueContext());
-        Assert.assertTrue(result.isError());
-        Assert.assertEquals("Failed", result.getMessage().get());
+        assertTrue(result.isError());
+        assertEquals("Failed", result.getMessage().get());
     }
 
     @Test
@@ -58,7 +60,7 @@ public class StringToIntegerConverterTest extends AbstractConverterTest {
                 getErrorMessage());
 
         assertValue(0, converter.convertToModel("", new ValueContext()));
-        Assert.assertEquals("0",
+        assertEquals("0",
                 converter.convertToPresentation(0, new ValueContext()));
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/data/converter/StringToLongConverterTest.java b/server/src/test/java/com/vaadin/tests/data/converter/StringToLongConverterTest.java
index fb8ab07d80..ed70763823 100644
--- a/server/src/test/java/com/vaadin/tests/data/converter/StringToLongConverterTest.java
+++ b/server/src/test/java/com/vaadin/tests/data/converter/StringToLongConverterTest.java
@@ -1,6 +1,7 @@
 package com.vaadin.tests.data.converter;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+
 import org.junit.Test;
 
 import com.vaadin.data.Result;
@@ -56,7 +57,7 @@ public class StringToLongConverterTest extends AbstractStringConverterTest {
                 getErrorMessage());
 
         assertValue((long) 0, converter.convertToModel("", new ValueContext()));
-        Assert.assertEquals("0",
+        assertEquals("0",
                 converter.convertToPresentation((long) 0, new ValueContext()));
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/data/selection/AbstractStaleSelectionTest.java b/server/src/test/java/com/vaadin/tests/data/selection/AbstractStaleSelectionTest.java
index 45e25cc867..1a8529302e 100644
--- a/server/src/test/java/com/vaadin/tests/data/selection/AbstractStaleSelectionTest.java
+++ b/server/src/test/java/com/vaadin/tests/data/selection/AbstractStaleSelectionTest.java
@@ -1,9 +1,11 @@
 package com.vaadin.tests.data.selection;
 
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import java.util.List;
 import java.util.concurrent.Future;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;
@@ -56,13 +58,12 @@ public abstract class AbstractStaleSelectionTest<S extends AbstractListing<StrBe
     }
 
     protected final void assertIsStale(StrBean bean) {
-        Assert.assertTrue("Bean with id " + bean.getId() + " should be stale.",
+        assertTrue("Bean with id " + bean.getId() + " should be stale.",
                 dataProvider.isStale(bean));
     }
 
     protected final void assertNotStale(StrBean bean) {
-        Assert.assertFalse(
-                "Bean with id " + bean.getId() + " should not be stale.",
+        assertFalse("Bean with id " + bean.getId() + " should not be stale.",
                 dataProvider.isStale(bean));
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/data/selection/GridStaleElementTest.java b/server/src/test/java/com/vaadin/tests/data/selection/GridStaleElementTest.java
index 64b7ecbc35..16ed3df97c 100644
--- a/server/src/test/java/com/vaadin/tests/data/selection/GridStaleElementTest.java
+++ b/server/src/test/java/com/vaadin/tests/data/selection/GridStaleElementTest.java
@@ -1,9 +1,11 @@
 package com.vaadin.tests.data.selection;
 
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import java.util.List;
 import java.util.concurrent.Future;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -64,15 +66,15 @@ public class GridStaleElementTest {
 
         assertStale(toReplace);
         model.getSelectedItems()
-                .forEach(item -> Assert.assertFalse(
+                .forEach(item -> assertFalse(
                         "Selection should not contain stale values",
                         dataProvider.isStale(item)));
 
         Object oldId = dataProvider.getId(toReplace);
-        Assert.assertTrue("Selection did not contain an item with matching Id.",
+        assertTrue("Selection did not contain an item with matching Id.",
                 model.getSelectedItems().stream().map(dataProvider::getId)
                         .anyMatch(oldId::equals));
-        Assert.assertTrue("Stale element is not considered selected.",
+        assertTrue("Stale element is not considered selected.",
                 model.isSelected(toReplace));
     }
 
@@ -91,26 +93,25 @@ public class GridStaleElementTest {
 
         assertStale(toReplace);
         model.getSelectedItems()
-                .forEach(i -> Assert.assertFalse(
+                .forEach(i -> assertFalse(
                         "Selection should not contain stale values",
                         dataProvider.isStale(i)));
 
-        Assert.assertTrue("Selection did not contain an item with matching Id.",
+        assertTrue("Selection did not contain an item with matching Id.",
                 model.getSelectedItems().stream().map(dataProvider::getId)
                         .filter(i -> dataProvider.getId(toReplace).equals(i))
                         .findFirst().isPresent());
-        Assert.assertTrue("Stale element is not considered selected.",
+        assertTrue("Stale element is not considered selected.",
                 model.isSelected(toReplace));
     }
 
     private void assertNotStale(StrBean bean) {
-        Assert.assertFalse(
-                "Bean with id " + bean.getId() + " should not be stale.",
+        assertFalse("Bean with id " + bean.getId() + " should not be stale.",
                 dataProvider.isStale(bean));
     }
 
     private void assertStale(StrBean bean) {
-        Assert.assertTrue("Bean with id " + bean.getId() + " should be stale.",
+        assertTrue("Bean with id " + bean.getId() + " should be stale.",
                 dataProvider.isStale(bean));
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/data/selection/StaleMultiSelectionTest.java b/server/src/test/java/com/vaadin/tests/data/selection/StaleMultiSelectionTest.java
index 9769ec3997..11918df0d6 100644
--- a/server/src/test/java/com/vaadin/tests/data/selection/StaleMultiSelectionTest.java
+++ b/server/src/test/java/com/vaadin/tests/data/selection/StaleMultiSelectionTest.java
@@ -1,10 +1,12 @@
 package com.vaadin.tests.data.selection;
 
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import java.util.Collection;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
-import org.junit.Assert;
 import org.junit.Test;
 import org.junit.runners.Parameterized.Parameters;
 
@@ -30,15 +32,15 @@ public class StaleMultiSelectionTest
 
         assertIsStale(toReplace);
         select.getSelectedItems()
-                .forEach(item -> Assert.assertFalse(
+                .forEach(item -> assertFalse(
                         "Selection should not contain stale values",
                         dataProvider.isStale(item)));
 
         Object oldId = dataProvider.getId(toReplace);
-        Assert.assertTrue("Selection did not contain an item with matching Id.",
+        assertTrue("Selection did not contain an item with matching Id.",
                 select.getSelectedItems().stream().map(dataProvider::getId)
                         .anyMatch(oldId::equals));
-        Assert.assertTrue("Stale element is not considered selected.",
+        assertTrue("Stale element is not considered selected.",
                 select.isSelected(toReplace));
     }
 
diff --git a/server/src/test/java/com/vaadin/tests/data/selection/StaleSingleSelectionTest.java b/server/src/test/java/com/vaadin/tests/data/selection/StaleSingleSelectionTest.java
index e8b354de9e..bdcdb46b18 100644
--- a/server/src/test/java/com/vaadin/tests/data/selection/StaleSingleSelectionTest.java
+++ b/server/src/test/java/com/vaadin/tests/data/selection/StaleSingleSelectionTest.java
@@ -1,10 +1,12 @@
 package com.vaadin.tests.data.selection;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+
 import java.util.Collection;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
-import org.junit.Assert;
 import org.junit.Test;
 import org.junit.runners.Parameterized.Parameters;
 
@@ -29,10 +31,10 @@ public class StaleSingleSelectionTest
         dataProvider.refreshItem(replacement);
 
         assertIsStale(toReplace);
-        Assert.assertFalse("Selection should not contain stale values",
+        assertFalse("Selection should not contain stale values",
                 dataProvider.isStale(select.getValue()));
 
-        Assert.assertEquals("Selected item id did not match original.",
+        assertEquals("Selected item id did not match original.",
                 toReplace.getId(), dataProvider.getId(select.getValue()));
     }
 
diff --git a/server/src/test/java/com/vaadin/tests/design/ComponentFactoryTest.java b/server/src/test/java/com/vaadin/tests/design/ComponentFactoryTest.java
index 813ff361f3..41be5aa6ab 100644
--- a/server/src/test/java/com/vaadin/tests/design/ComponentFactoryTest.java
+++ b/server/src/test/java/com/vaadin/tests/design/ComponentFactoryTest.java
@@ -15,12 +15,13 @@
  */
 package com.vaadin.tests.design;
 
+import static org.junit.Assert.assertEquals;
+
 import java.io.ByteArrayInputStream;
 import java.util.ArrayList;
 import java.util.List;
 
 import org.junit.After;
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.ui.AbstractComponent;
@@ -69,9 +70,8 @@ public class ComponentFactoryTest {
 
         Design.read(new ByteArrayInputStream("<vaadin-label />".getBytes()));
 
-        Assert.assertEquals("There should be one message logged", 1,
-                messages.size());
-        Assert.assertEquals("Requested class " + Label.class.getCanonicalName(),
+        assertEquals("There should be one message logged", 1, messages.size());
+        assertEquals("Requested class " + Label.class.getCanonicalName(),
                 messages.get(0));
     }
 
@@ -109,10 +109,8 @@ public class ComponentFactoryTest {
         DesignContext designContext = new DesignContext();
         designContext.getDefaultInstance(new DefaultInstanceTestComponent());
 
-        Assert.assertEquals("There should be one class requests", 1,
-                classes.size());
-        Assert.assertEquals(
-                "First class should be DefaultInstanceTestComponent",
+        assertEquals("There should be one class requests", 1, classes.size());
+        assertEquals("First class should be DefaultInstanceTestComponent",
                 DefaultInstanceTestComponent.class.getName(), classes.get(0));
     }
 
diff --git a/server/src/test/java/com/vaadin/tests/design/ComponentMapperTest.java b/server/src/test/java/com/vaadin/tests/design/ComponentMapperTest.java
index 25062f76f4..e9eefa3e6b 100644
--- a/server/src/test/java/com/vaadin/tests/design/ComponentMapperTest.java
+++ b/server/src/test/java/com/vaadin/tests/design/ComponentMapperTest.java
@@ -15,11 +15,13 @@
  */
 package com.vaadin.tests.design;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.ui.Component;
@@ -100,11 +102,11 @@ public class ComponentMapperTest {
         Component component = Design
                 .read(new ByteArrayInputStream("<custom-foobar />".getBytes()));
 
-        Assert.assertTrue(
+        assertTrue(
                 "<custom-foobar> should resolve "
                         + ComponentWithCustomTagName.class.getSimpleName(),
                 component instanceof ComponentWithCustomTagName);
-        Assert.assertEquals("custom-foobar",
+        assertEquals("custom-foobar",
                 ((ComponentWithCustomTagName) component).tagName);
     }
 
@@ -119,7 +121,7 @@ public class ComponentMapperTest {
         Design.write(component, bos);
         String writtenDesign = new String(bos.toByteArray());
 
-        Assert.assertTrue(
+        assertTrue(
                 "Written design should contain \"<custom-special\", but instead got "
                         + writtenDesign,
                 writtenDesign.contains("<custom-special"));
diff --git a/server/src/test/java/com/vaadin/tests/design/DeclarativeTestBaseBase.java b/server/src/test/java/com/vaadin/tests/design/DeclarativeTestBaseBase.java
index a3b6fbeeeb..f3e7c237a8 100644
--- a/server/src/test/java/com/vaadin/tests/design/DeclarativeTestBaseBase.java
+++ b/server/src/test/java/com/vaadin/tests/design/DeclarativeTestBaseBase.java
@@ -16,6 +16,7 @@
 package com.vaadin.tests.design;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
+import static org.junit.Assert.assertNull;
 
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
@@ -95,11 +96,11 @@ public abstract class DeclarativeTestBaseBase<T extends Component> {
 
     protected void assertEquals(String message, Object o1, Object o2) {
         if (o1 == null) {
-            Assert.assertNull(message, o2);
+            assertNull(message, o2);
             return;
         }
         if (o2 == null) {
-            Assert.assertNull(message, o1);
+            assertNull(message, o1);
             return;
         }
 
diff --git a/server/src/test/java/com/vaadin/tests/design/DesignFormatterTest.java b/server/src/test/java/com/vaadin/tests/design/DesignFormatterTest.java
index f448f5c2b2..9f6253067a 100644
--- a/server/src/test/java/com/vaadin/tests/design/DesignFormatterTest.java
+++ b/server/src/test/java/com/vaadin/tests/design/DesignFormatterTest.java
@@ -16,7 +16,9 @@
 package com.vaadin.tests.design;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
 
 import java.io.File;
 import java.math.BigDecimal;
@@ -25,7 +27,6 @@ import java.util.Date;
 import java.util.HashSet;
 import java.util.TimeZone;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -80,15 +81,15 @@ public class DesignFormatterTest {
         assertEquals("", formatter.format(true));
         assertEquals("false", formatter.format(false));
 
-        Assert.assertTrue(formatter.parse("true", boolean.class));
-        Assert.assertTrue(formatter.parse("foobar", boolean.class));
-        Assert.assertTrue(formatter.parse("", boolean.class));
-        Assert.assertFalse(formatter.parse("false", boolean.class));
+        assertTrue(formatter.parse("true", boolean.class));
+        assertTrue(formatter.parse("foobar", boolean.class));
+        assertTrue(formatter.parse("", boolean.class));
+        assertFalse(formatter.parse("false", boolean.class));
 
-        Assert.assertTrue(formatter.parse("true", Boolean.class));
-        Assert.assertTrue(formatter.parse("foobar", Boolean.class));
-        Assert.assertTrue(formatter.parse("", Boolean.class));
-        Assert.assertFalse(formatter.parse("false", Boolean.class));
+        assertTrue(formatter.parse("true", Boolean.class));
+        assertTrue(formatter.parse("foobar", Boolean.class));
+        assertTrue(formatter.parse("", Boolean.class));
+        assertFalse(formatter.parse("false", Boolean.class));
     }
 
     @Test
@@ -236,7 +237,7 @@ public class DesignFormatterTest {
     protected void assertInvalidShortcut(String shortcut) {
         try {
             formatter.parse(shortcut, ShortcutAction.class);
-            Assert.fail("Invalid shortcut '" + shortcut + "' should throw");
+            fail("Invalid shortcut '" + shortcut + "' should throw");
         } catch (IllegalArgumentException e) {
             // expected
         }
diff --git a/server/src/test/java/com/vaadin/tests/design/DesignReadInConstructorTest.java b/server/src/test/java/com/vaadin/tests/design/DesignReadInConstructorTest.java
index b870e55f13..f97842b0cf 100644
--- a/server/src/test/java/com/vaadin/tests/design/DesignReadInConstructorTest.java
+++ b/server/src/test/java/com/vaadin/tests/design/DesignReadInConstructorTest.java
@@ -16,6 +16,7 @@
 package com.vaadin.tests.design;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
+import static org.junit.Assert.assertEquals;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
@@ -26,7 +27,6 @@ import org.jsoup.Jsoup;
 import org.jsoup.nodes.Attribute;
 import org.jsoup.nodes.Document;
 import org.jsoup.nodes.Element;
-import org.junit.Assert;
 import org.junit.Ignore;
 import org.junit.Test;
 
@@ -37,7 +37,7 @@ public class DesignReadInConstructorTest {
     @Test
     public void useDesignReadInConstructor() {
         DesignReadInConstructor dric = new DesignReadInConstructor();
-        Assert.assertEquals(3, dric.getComponentCount());
+        assertEquals(3, dric.getComponentCount());
     }
 
     @Test
@@ -55,7 +55,7 @@ public class DesignReadInConstructorTest {
     }
 
     private void assertJsoupTreeEquals(Element expected, Element actual) {
-        Assert.assertEquals(expected.tagName(), actual.tagName());
+        assertEquals(expected.tagName(), actual.tagName());
 
         Set<String> keys = new HashSet<>();
 
@@ -66,12 +66,11 @@ public class DesignReadInConstructorTest {
             keys.add(attr.getKey());
         }
         for (String attributeKey : keys) {
-            Assert.assertEquals(expected.attr(attributeKey),
+            assertEquals(expected.attr(attributeKey),
                     actual.attr(attributeKey));
         }
 
-        Assert.assertEquals(expected.children().size(),
-                actual.children().size());
+        assertEquals(expected.children().size(), actual.children().size());
         for (int i = 0; i < expected.children().size(); i++) {
             assertJsoupTreeEquals(expected.child(i), actual.child(i));
         }
diff --git a/server/src/test/java/com/vaadin/tests/design/DesignTest.java b/server/src/test/java/com/vaadin/tests/design/DesignTest.java
index 95749aed68..115dde4934 100644
--- a/server/src/test/java/com/vaadin/tests/design/DesignTest.java
+++ b/server/src/test/java/com/vaadin/tests/design/DesignTest.java
@@ -15,13 +15,14 @@
  */
 package com.vaadin.tests.design;
 
+import static org.junit.Assert.assertEquals;
+
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.util.Iterator;
 
-import org.junit.Assert;
 import org.junit.Ignore;
 import org.junit.Test;
 
@@ -43,13 +44,11 @@ public class DesignTest {
         Component root = Design.read(getClass()
                 .getResourceAsStream("verticallayout-two-children.html"));
         VerticalLayout rootLayout = (VerticalLayout) root;
-        Assert.assertEquals(VerticalLayout.class, root.getClass());
+        assertEquals(VerticalLayout.class, root.getClass());
 
-        Assert.assertEquals(2, rootLayout.getComponentCount());
-        Assert.assertEquals(TextField.class,
-                rootLayout.getComponent(0).getClass());
-        Assert.assertEquals(Button.class,
-                rootLayout.getComponent(1).getClass());
+        assertEquals(2, rootLayout.getComponentCount());
+        assertEquals(TextField.class, rootLayout.getComponent(0).getClass());
+        assertEquals(Button.class, rootLayout.getComponent(1).getClass());
     }
 
     @Test(expected = DesignException.class)
diff --git a/server/src/test/java/com/vaadin/tests/design/FieldNameWhichConflictsWithGettersTest.java b/server/src/test/java/com/vaadin/tests/design/FieldNameWhichConflictsWithGettersTest.java
index 91e7e89627..0b70006965 100644
--- a/server/src/test/java/com/vaadin/tests/design/FieldNameWhichConflictsWithGettersTest.java
+++ b/server/src/test/java/com/vaadin/tests/design/FieldNameWhichConflictsWithGettersTest.java
@@ -16,6 +16,8 @@
 package com.vaadin.tests.design;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
@@ -23,7 +25,6 @@ import java.io.IOException;
 import org.jsoup.Jsoup;
 import org.jsoup.nodes.Document;
 import org.jsoup.nodes.Element;
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.annotations.DesignRoot;
@@ -48,8 +49,8 @@ public class FieldNameWhichConflictsWithGettersTest {
     @Test
     public void readWithConflictingFields() {
         MyVerticalLayout v = new MyVerticalLayout();
-        Assert.assertNotNull(v.caption);
-        Assert.assertNotNull(v.description);
+        assertNotNull(v.caption);
+        assertNotNull(v.description);
     }
 
     @Test
@@ -72,13 +73,13 @@ public class FieldNameWhichConflictsWithGettersTest {
         Document doc = Jsoup.parse(str);
         Element body = doc.body();
         Element captionElement = body.getElementById("caption");
-        Assert.assertNotNull(captionElement);
-        Assert.assertEquals("vaadin-label", captionElement.tagName());
+        assertNotNull(captionElement);
+        assertEquals("vaadin-label", captionElement.tagName());
 
         Element descriptionElement = captionElement.nextElementSibling();
-        Assert.assertNotNull(descriptionElement);
-        Assert.assertEquals("vaadin-text-field", descriptionElement.tagName());
-        Assert.assertEquals("description", descriptionElement.attr("_id"));
+        assertNotNull(descriptionElement);
+        assertEquals("vaadin-text-field", descriptionElement.tagName());
+        assertEquals("description", descriptionElement.attr("_id"));
 
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/design/InvalidTagNamesTest.java b/server/src/test/java/com/vaadin/tests/design/InvalidTagNamesTest.java
index 98ca82d646..229e4d69ac 100644
--- a/server/src/test/java/com/vaadin/tests/design/InvalidTagNamesTest.java
+++ b/server/src/test/java/com/vaadin/tests/design/InvalidTagNamesTest.java
@@ -16,10 +16,11 @@
 package com.vaadin.tests.design;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
 
 import java.io.ByteArrayInputStream;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.ui.Button;
@@ -38,7 +39,7 @@ public class InvalidTagNamesTest {
     public void emptyTag() {
         // JSoup parses empty tags into text nodes
         Component c = readDesign("<>foo</>");
-        Assert.assertNull(c);
+        assertNull(c);
     }
 
     @Test(expected = DesignException.class)
@@ -51,7 +52,7 @@ public class InvalidTagNamesTest {
         // JSoup will refuse to parse tags starting with - and convert them into
         // text nodes instead
         Component c = readDesign("<-v>foo</-v>");
-        Assert.assertNull(c);
+        assertNull(c);
     }
 
     @Test(expected = DesignException.class)
@@ -69,7 +70,7 @@ public class InvalidTagNamesTest {
     // parsed currently as <vaadin-button> (this should not be considered API)
     public void tagEndsInDash() {
         Component c = readDesign("<vaadin-button-></vaadin-button->");
-        Assert.assertTrue(c.getClass() == Button.class);
+        assertTrue(c.getClass() == Button.class);
     }
 
     // @Test(expected = DesignException.class)
@@ -77,7 +78,7 @@ public class InvalidTagNamesTest {
     // parsed currently as <vaadin-button> (this should not be considered API)
     public void tagEndsInTwoDashes() {
         Component c = readDesign("<vaadin-button--></vaadin-button-->");
-        Assert.assertTrue(c.getClass() == Button.class);
+        assertTrue(c.getClass() == Button.class);
     }
 
     // @Test(expected = DesignException.class)
@@ -85,7 +86,7 @@ public class InvalidTagNamesTest {
     // parsed currently as <vaadin-button> (this should not be considered API)
     public void tagWithTwoDashes() {
         Component c = readDesign("<vaadin--button></vaadin--button>");
-        Assert.assertTrue(c.getClass() == Button.class);
+        assertTrue(c.getClass() == Button.class);
     }
 
     @Test(expected = DesignException.class)
diff --git a/server/src/test/java/com/vaadin/tests/design/designroot/CompositeDesignRootTest.java b/server/src/test/java/com/vaadin/tests/design/designroot/CompositeDesignRootTest.java
index fbe0b029f2..e18ef0b409 100644
--- a/server/src/test/java/com/vaadin/tests/design/designroot/CompositeDesignRootTest.java
+++ b/server/src/test/java/com/vaadin/tests/design/designroot/CompositeDesignRootTest.java
@@ -15,7 +15,9 @@
  */
 package com.vaadin.tests.design.designroot;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+
 import org.junit.Test;
 
 import com.vaadin.tests.server.component.composite.MyPrefilledComposite;
@@ -29,11 +31,11 @@ public class CompositeDesignRootTest {
         CompositeDesignRootForVerticalLayout r = new CompositeDesignRootForVerticalLayout();
         // Composition root, should be VerticalLayout
         Component compositionRoot = r.iterator().next();
-        Assert.assertNotNull(compositionRoot);
-        Assert.assertEquals(VerticalLayout.class, compositionRoot.getClass());
-        Assert.assertNotNull(r.ok);
-        Assert.assertNotNull(r.cancel);
-        Assert.assertEquals("original", r.preInitializedField.getValue());
+        assertNotNull(compositionRoot);
+        assertEquals(VerticalLayout.class, compositionRoot.getClass());
+        assertNotNull(r.ok);
+        assertNotNull(r.cancel);
+        assertEquals("original", r.preInitializedField.getValue());
     }
 
     @Test
@@ -41,9 +43,8 @@ public class CompositeDesignRootTest {
         CompositeDesignRootForMyComposite r = new CompositeDesignRootForMyComposite();
         // Composition root, should be MyPrefilledcomposite
         Component compositionRoot = r.iterator().next();
-        Assert.assertNotNull(compositionRoot);
-        Assert.assertEquals(MyPrefilledComposite.class,
-                compositionRoot.getClass());
+        assertNotNull(compositionRoot);
+        assertEquals(MyPrefilledComposite.class, compositionRoot.getClass());
 
     }
 
diff --git a/server/src/test/java/com/vaadin/tests/design/designroot/CustomComponentDesignRootTest.java b/server/src/test/java/com/vaadin/tests/design/designroot/CustomComponentDesignRootTest.java
index 5331fdba4b..bab95d9e19 100644
--- a/server/src/test/java/com/vaadin/tests/design/designroot/CustomComponentDesignRootTest.java
+++ b/server/src/test/java/com/vaadin/tests/design/designroot/CustomComponentDesignRootTest.java
@@ -15,7 +15,9 @@
  */
 package com.vaadin.tests.design.designroot;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+
 import org.junit.Test;
 
 import com.vaadin.tests.server.component.customcomponent.MyPrefilledCustomComponent;
@@ -29,11 +31,11 @@ public class CustomComponentDesignRootTest {
         CustomComponentDesignRootForVerticalLayout r = new CustomComponentDesignRootForVerticalLayout();
         // Composition root, should be VerticalLayout
         Component compositionRoot = r.iterator().next();
-        Assert.assertNotNull(compositionRoot);
-        Assert.assertEquals(VerticalLayout.class, compositionRoot.getClass());
-        Assert.assertNotNull(r.ok);
-        Assert.assertNotNull(r.cancel);
-        Assert.assertEquals("original", r.preInitializedField.getValue());
+        assertNotNull(compositionRoot);
+        assertEquals(VerticalLayout.class, compositionRoot.getClass());
+        assertNotNull(r.ok);
+        assertNotNull(r.cancel);
+        assertEquals("original", r.preInitializedField.getValue());
     }
 
     @Test
@@ -41,8 +43,8 @@ public class CustomComponentDesignRootTest {
         CustomComponentDesignRootForMyCustomComponent r = new CustomComponentDesignRootForMyCustomComponent();
         // Composition root, should be MyPrefilledCustomComponent
         Component compositionRoot = r.iterator().next();
-        Assert.assertNotNull(compositionRoot);
-        Assert.assertEquals(MyPrefilledCustomComponent.class,
+        assertNotNull(compositionRoot);
+        assertEquals(MyPrefilledCustomComponent.class,
                 compositionRoot.getClass());
 
     }
diff --git a/server/src/test/java/com/vaadin/tests/design/designroot/DesignRootTest.java b/server/src/test/java/com/vaadin/tests/design/designroot/DesignRootTest.java
index 3f35c7602d..fb1e216800 100644
--- a/server/src/test/java/com/vaadin/tests/design/designroot/DesignRootTest.java
+++ b/server/src/test/java/com/vaadin/tests/design/designroot/DesignRootTest.java
@@ -15,40 +15,42 @@
  */
 package com.vaadin.tests.design.designroot;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+
 import org.junit.Test;
 
 public class DesignRootTest {
     @Test
     public void designAnnotationWithoutFilename() {
         DesignWithEmptyAnnotation d = new DesignWithEmptyAnnotation();
-        Assert.assertNotNull(d.ok);
-        Assert.assertNotNull(d.CaNCEL);
-        Assert.assertEquals("original", d.preInitializedField.getValue());
+        assertNotNull(d.ok);
+        assertNotNull(d.CaNCEL);
+        assertEquals("original", d.preInitializedField.getValue());
     }
 
     @Test
     public void designAnnotationWithFilename() {
         DesignWithAnnotation d = new DesignWithAnnotation();
-        Assert.assertNotNull(d.ok);
-        Assert.assertNotNull(d.cancel);
-        Assert.assertEquals("original", d.preInitializedField.getValue());
+        assertNotNull(d.ok);
+        assertNotNull(d.cancel);
+        assertEquals("original", d.preInitializedField.getValue());
     }
 
     @Test
     public void extendedDesignAnnotationWithoutFilename() {
         DesignWithEmptyAnnotation d = new ExtendedDesignWithEmptyAnnotation();
-        Assert.assertNotNull(d.ok);
-        Assert.assertNotNull(d.CaNCEL);
-        Assert.assertEquals("original", d.preInitializedField.getValue());
+        assertNotNull(d.ok);
+        assertNotNull(d.CaNCEL);
+        assertEquals("original", d.preInitializedField.getValue());
     }
 
     @Test
     public void extendedDesignAnnotationWithFilename() {
         DesignWithAnnotation d = new ExtendedDesignWithAnnotation();
-        Assert.assertNotNull(d.ok);
-        Assert.assertNotNull(d.cancel);
-        Assert.assertEquals("original", d.preInitializedField.getValue());
+        assertNotNull(d.ok);
+        assertNotNull(d.cancel);
+        assertEquals("original", d.preInitializedField.getValue());
     }
 
 }
diff --git a/server/src/test/java/com/vaadin/tests/event/EventRouterTest.java b/server/src/test/java/com/vaadin/tests/event/EventRouterTest.java
index a290d43ea3..013c8b8f58 100644
--- a/server/src/test/java/com/vaadin/tests/event/EventRouterTest.java
+++ b/server/src/test/java/com/vaadin/tests/event/EventRouterTest.java
@@ -15,10 +15,12 @@
  */
 package com.vaadin.tests.event;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+
 import java.lang.reflect.Method;
 
 import org.easymock.EasyMock;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -70,10 +72,10 @@ public class EventRouterTest {
         EasyMock.replay(component, listener);
         try {
             router.fireEvent(new Component.Event(component));
-            Assert.fail("Did not receive expected exception from listener");
+            fail("Did not receive expected exception from listener");
         } catch (RuntimeException e) {
             // e is a ListenerMethod@MethodException
-            Assert.assertEquals("listener failed", e.getCause().getMessage());
+            assertEquals("listener failed", e.getCause().getMessage());
         }
         EasyMock.verify(listener);
     }
diff --git a/server/src/test/java/com/vaadin/tests/server/ClassesSerializableTest.java b/server/src/test/java/com/vaadin/tests/server/ClassesSerializableTest.java
index aa37e860d7..d85c23b5f8 100644
--- a/server/src/test/java/com/vaadin/tests/server/ClassesSerializableTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/ClassesSerializableTest.java
@@ -1,5 +1,7 @@
 package com.vaadin.tests.server;
 
+import static org.junit.Assert.fail;
+
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.File;
@@ -26,7 +28,6 @@ import java.util.jar.JarFile;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.ui.Component;
@@ -213,7 +214,7 @@ public class ClassesSerializableTest {
                         field.getDeclaringClass().getName(), field.getName()))
                 .collect(Collectors.joining(", "));
 
-        Assert.fail("Fields with functional types that are not serializable: "
+        fail("Fields with functional types that are not serializable: "
                 + nonSerializableString);
     }
 
@@ -233,9 +234,8 @@ public class ClassesSerializableTest {
                 nonSerializableString += ")";
             }
         }
-        Assert.fail(
-                "Serializable not implemented by the following classes and interfaces: "
-                        + nonSerializableString);
+        fail("Serializable not implemented by the following classes and interfaces: "
+                + nonSerializableString);
 
     }
 
diff --git a/server/src/test/java/com/vaadin/tests/server/CsrfTokenMissingTest.java b/server/src/test/java/com/vaadin/tests/server/CsrfTokenMissingTest.java
index 2f4ba832d3..da1edeff59 100644
--- a/server/src/test/java/com/vaadin/tests/server/CsrfTokenMissingTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/CsrfTokenMissingTest.java
@@ -15,6 +15,9 @@
  */
 package com.vaadin.tests.server;
 
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import java.util.UUID;
 import java.util.logging.Level;
 import java.util.logging.Logger;
@@ -23,7 +26,6 @@ import javax.servlet.ServletException;
 import javax.servlet.http.HttpServletRequest;
 
 import org.easymock.EasyMock;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -149,7 +151,7 @@ public class CsrfTokenMissingTest {
         } catch (JsonException e) {
             LOGGER.log(Level.SEVERE, "", e);
 
-            Assert.assertTrue(false);
+            assertTrue(false);
             return null;
         }
     }
@@ -196,8 +198,8 @@ public class CsrfTokenMissingTest {
 
         RpcRequest rpcRequest = createRequest();
 
-        Assert.assertTrue(isDefaultToken(rpcRequest));
-        Assert.assertFalse(isRequestValid(rpcRequest));
+        assertTrue(isDefaultToken(rpcRequest));
+        assertFalse(isRequestValid(rpcRequest));
     }
 
     @Test
@@ -206,8 +208,8 @@ public class CsrfTokenMissingTest {
 
         RpcRequest rpcRequest = createRequest();
 
-        Assert.assertTrue(isDefaultToken(rpcRequest));
-        Assert.assertTrue(isRequestValid(rpcRequest));
+        assertTrue(isDefaultToken(rpcRequest));
+        assertTrue(isRequestValid(rpcRequest));
     }
 
     @Test
@@ -216,8 +218,8 @@ public class CsrfTokenMissingTest {
 
         RpcRequest rpcRequest = createRequest();
 
-        Assert.assertTrue(isInvalidToken(rpcRequest));
-        Assert.assertFalse(isRequestValid(rpcRequest));
+        assertTrue(isInvalidToken(rpcRequest));
+        assertFalse(isRequestValid(rpcRequest));
     }
 
     @Test
@@ -226,8 +228,8 @@ public class CsrfTokenMissingTest {
 
         RpcRequest rpcRequest = createRequest();
 
-        Assert.assertTrue(isInvalidToken(rpcRequest));
-        Assert.assertTrue(isRequestValid(rpcRequest));
+        assertTrue(isInvalidToken(rpcRequest));
+        assertTrue(isRequestValid(rpcRequest));
     }
 
     @Test
@@ -236,8 +238,8 @@ public class CsrfTokenMissingTest {
 
         RpcRequest rpcRequest = createRequest();
 
-        Assert.assertTrue(isValidToken(rpcRequest));
-        Assert.assertTrue(isRequestValid(rpcRequest));
+        assertTrue(isValidToken(rpcRequest));
+        assertTrue(isRequestValid(rpcRequest));
     }
 
     @Test
@@ -246,8 +248,8 @@ public class CsrfTokenMissingTest {
 
         RpcRequest rpcRequest = createRequest();
 
-        Assert.assertTrue(isValidToken(rpcRequest));
-        Assert.assertTrue(isRequestValid(rpcRequest));
+        assertTrue(isValidToken(rpcRequest));
+        assertTrue(isRequestValid(rpcRequest));
     }
 
 }
diff --git a/server/src/test/java/com/vaadin/tests/server/StreamResourceTest.java b/server/src/test/java/com/vaadin/tests/server/StreamResourceTest.java
index 7f6e17d8f8..438bf31925 100644
--- a/server/src/test/java/com/vaadin/tests/server/StreamResourceTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/StreamResourceTest.java
@@ -15,8 +15,10 @@
  */
 package com.vaadin.tests.server;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+
 import org.easymock.EasyMock;
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.server.StreamResource;
@@ -33,7 +35,7 @@ public class StreamResourceTest {
         StreamResource resource1 = new StreamResource(null, null);
         StreamResource resource2 = new StreamResource(null, null);
 
-        Assert.assertEquals(resource1, resource2);
+        assertEquals(resource1, resource2);
     }
 
     @Test
@@ -42,7 +44,7 @@ public class StreamResourceTest {
         StreamResource resource2 = new StreamResource(
                 EasyMock.createMock(StreamSource.class), "");
 
-        Assert.assertNotEquals(resource1, resource2);
+        assertNotEquals(resource1, resource2);
     }
 
     @Test
diff --git a/server/src/test/java/com/vaadin/tests/server/component/AbstractListenerMethodsTestBase.java b/server/src/test/java/com/vaadin/tests/server/component/AbstractListenerMethodsTestBase.java
index 2203635430..8a31b8cf98 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/AbstractListenerMethodsTestBase.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/AbstractListenerMethodsTestBase.java
@@ -1,5 +1,8 @@
 package com.vaadin.tests.server.component;
 
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.util.Collection;
@@ -7,7 +10,6 @@ import java.util.HashSet;
 import java.util.Set;
 
 import org.easymock.EasyMock;
-import org.junit.Assert;
 
 import com.vaadin.shared.Registration;
 import com.vaadin.tests.VaadinClasses;
@@ -54,13 +56,11 @@ public abstract class AbstractListenerMethodsTestBase {
                                         .getName()
                                 + ";");
                         System.out.println("import " + c.getName() + ";");
-                        System.out
-                                .println(
-                                        "public class " + c.getSimpleName()
-                                                + "Listeners extends "
-                                                + AbstractListenerMethodsTestBase.class
-                                                        .getSimpleName()
-                                                + " {");
+                        System.out.println("public class " + c.getSimpleName()
+                                + "Listeners extends "
+                                + AbstractListenerMethodsTestBase.class
+                                        .getSimpleName()
+                                + " {");
                     }
 
                     String listenerClassName = m.getParameterTypes()[0]
@@ -163,11 +163,10 @@ public abstract class AbstractListenerMethodsTestBase {
             SecurityException, IllegalAccessException,
             InvocationTargetException, NoSuchMethodException {
         Collection<?> registeredListeners = getListeners(c, eventClass);
-        Assert.assertEquals("Number of listeners", expectedListeners.length,
+        assertEquals("Number of listeners", expectedListeners.length,
                 registeredListeners.size());
 
-        Assert.assertArrayEquals(expectedListeners,
-                registeredListeners.toArray());
+        assertArrayEquals(expectedListeners, registeredListeners.toArray());
 
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/server/component/ComponentSizeParseTest.java b/server/src/test/java/com/vaadin/tests/server/component/ComponentSizeParseTest.java
index c0de675414..6403f9f956 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/ComponentSizeParseTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/ComponentSizeParseTest.java
@@ -16,7 +16,8 @@
 
 package com.vaadin.tests.server.component;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+
 import org.junit.Test;
 
 import com.vaadin.server.Sizeable.Unit;
@@ -49,13 +50,13 @@ public class ComponentSizeParseTest {
         LabelWithPublicState label = new LabelWithPublicState();
         label.setHeight(string);
 
-        Assert.assertEquals(amout, label.getHeight(), 0);
-        Assert.assertEquals(unit, label.getHeightUnits());
+        assertEquals(amout, label.getHeight(), 0);
+        assertEquals(unit, label.getHeightUnits());
 
         label = new LabelWithPublicState();
 
         label.setHeight(10, unit);
         label.beforeClientResponse(true);
-        Assert.assertEquals(string, label.getState().height);
+        assertEquals(string, label.getState().height);
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/server/component/DeclarativeMarginTestBase.java b/server/src/test/java/com/vaadin/tests/server/component/DeclarativeMarginTestBase.java
index 66f6076f7b..f90b69bf1c 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/DeclarativeMarginTestBase.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/DeclarativeMarginTestBase.java
@@ -15,7 +15,8 @@
  */
 package com.vaadin.tests.server.component;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
 
 import com.vaadin.shared.ui.MarginInfo;
 import com.vaadin.tests.design.DeclarativeTestBase;
@@ -34,7 +35,7 @@ public abstract class DeclarativeMarginTestBase<L extends Layout & MarginHandler
         }
         design += " />";
         L layout = read(design);
-        Assert.assertTrue(layout.isSpacing());
+        assertTrue(layout.isSpacing());
         testWrite(design, layout);
 
         // Spacing off
@@ -44,7 +45,7 @@ public abstract class DeclarativeMarginTestBase<L extends Layout & MarginHandler
         }
         design += " />";
         layout = read(design);
-        Assert.assertFalse(layout.isSpacing());
+        assertFalse(layout.isSpacing());
         testWrite(design, layout);
     }
 
@@ -65,7 +66,7 @@ public abstract class DeclarativeMarginTestBase<L extends Layout & MarginHandler
             // introspection and MarginInfo is not a proper bean. It ends up
             // considering *all* MarginInfo objects equal... (#18229)
             L layout = read(design);
-            Assert.assertEquals("For tag: " + design, marginToTest,
+            assertEquals("For tag: " + design, marginToTest,
                     layout.getMargin());
 
             testWrite(design, layout);
diff --git a/server/src/test/java/com/vaadin/tests/server/component/FinalMethodTest.java b/server/src/test/java/com/vaadin/tests/server/component/FinalMethodTest.java
index 71d423808e..718f9d0222 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/FinalMethodTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/FinalMethodTest.java
@@ -1,10 +1,11 @@
 package com.vaadin.tests.server.component;
 
+import static org.junit.Assert.assertTrue;
+
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.util.HashSet;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.tests.VaadinClasses;
@@ -29,7 +30,7 @@ public class FinalMethodTest {
             ensureNoFinalMethods(c, tested);
             count++;
         }
-        Assert.assertTrue(count > 0);
+        assertTrue(count > 0);
     }
 
     private void ensureNoFinalMethods(Class<?> clazz,
diff --git a/server/src/test/java/com/vaadin/tests/server/component/ItemCaptionGeneratorTest.java b/server/src/test/java/com/vaadin/tests/server/component/ItemCaptionGeneratorTest.java
index 1f80e46476..a9f9b48471 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/ItemCaptionGeneratorTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/ItemCaptionGeneratorTest.java
@@ -1,9 +1,10 @@
 package com.vaadin.tests.server.component;
 
+import static org.junit.Assert.assertEquals;
+
 import java.util.ArrayList;
 import java.util.Collection;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.data.provider.DataGenerator;
@@ -71,9 +72,8 @@ public class ItemCaptionGeneratorTest {
             listing.getDataCommunicator().addDataGenerator(dataGenerator);
             listing.getDataCommunicator().beforeClientResponse(true);
 
-            Assert.assertEquals(
-                    listing.getClass().getName()
-                            + " does not convert null caption from generator to empty string",
+            assertEquals(listing.getClass().getName()
+                    + " does not convert null caption from generator to empty string",
                     "",
                     dataGenerator.generated.hasKey((String) listing.getData())
                             ? dataGenerator.generated.getString(
diff --git a/server/src/test/java/com/vaadin/tests/server/component/StateGetDoesNotMarkDirtyTest.java b/server/src/test/java/com/vaadin/tests/server/component/StateGetDoesNotMarkDirtyTest.java
index 99c686743c..459a876467 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/StateGetDoesNotMarkDirtyTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/StateGetDoesNotMarkDirtyTest.java
@@ -1,5 +1,7 @@
 package com.vaadin.tests.server.component;
 
+import static org.junit.Assert.assertTrue;
+
 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
@@ -9,7 +11,6 @@ import java.util.HashSet;
 import java.util.Locale;
 import java.util.Set;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.Mockito;
@@ -96,7 +97,7 @@ public class StateGetDoesNotMarkDirtyTest {
                 }
             }
         }
-        Assert.assertTrue(count > 0);
+        assertTrue(count > 0);
     }
 
     private void prepareMockUI(Component newInstance) {
diff --git a/server/src/test/java/com/vaadin/tests/server/component/WriteEmptyDesignTest.java b/server/src/test/java/com/vaadin/tests/server/component/WriteEmptyDesignTest.java
index 4c65744224..c3fe9e4a4b 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/WriteEmptyDesignTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/WriteEmptyDesignTest.java
@@ -15,6 +15,8 @@
  */
 package com.vaadin.tests.server.component;
 
+import static org.junit.Assert.assertEquals;
+
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
@@ -22,7 +24,6 @@ import java.io.OutputStream;
 import org.jsoup.Jsoup;
 import org.jsoup.nodes.Document;
 import org.jsoup.nodes.Element;
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.ui.Component;
@@ -54,7 +55,7 @@ public class WriteEmptyDesignTest {
     private void checkHtml(String html) {
         Document doc = Jsoup.parse(html);
         Element body = doc.body();
-        Assert.assertEquals("There should be no elements in the html body.", "",
+        assertEquals("There should be no elements in the html body.", "",
                 body.html());
     }
-}
\ No newline at end of file
+}
diff --git a/server/src/test/java/com/vaadin/tests/server/component/abstractlisting/AbstractListingDeclarativeTest.java b/server/src/test/java/com/vaadin/tests/server/component/abstractlisting/AbstractListingDeclarativeTest.java
index a3b9e244cf..05e31fc0c1 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/abstractlisting/AbstractListingDeclarativeTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/abstractlisting/AbstractListingDeclarativeTest.java
@@ -170,7 +170,7 @@ public abstract class AbstractListingDeclarativeTest<T extends AbstractListing>
 
     private void testReadData(String design, T expected, T read,
             DesignContext context) {
-        Assert.assertEquals(
+        assertEquals(
                 read.getDataCommunicator().getDataProvider()
                         .size(new Query<>()),
                 expected.getDataCommunicator().getDataProvider()
diff --git a/server/src/test/java/com/vaadin/tests/server/component/abstractmultiselect/AbstractMultiSelectDeclarativeTest.java b/server/src/test/java/com/vaadin/tests/server/component/abstractmultiselect/AbstractMultiSelectDeclarativeTest.java
index 1b11ab11dc..35f7647049 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/abstractmultiselect/AbstractMultiSelectDeclarativeTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/abstractmultiselect/AbstractMultiSelectDeclarativeTest.java
@@ -68,7 +68,7 @@ public abstract class AbstractMultiSelectDeclarativeTest<T extends AbstractMulti
 
         DesignContext context = readComponentAndCompare(design, component,
                 ctxt -> configureContext(type, attribute, component, ctxt));
-        Assert.assertEquals(type,
+        assertEquals(type,
                 context.getCustomAttributes(context.getRootComponent())
                         .get(attribute));
         context = new DesignContext();
@@ -97,7 +97,7 @@ public abstract class AbstractMultiSelectDeclarativeTest<T extends AbstractMulti
 
         DesignContext context = readComponentAndCompare(design, component,
                 ctxt -> configureContext(type, attribute, component, ctxt));
-        Assert.assertEquals(type,
+        assertEquals(type,
                 context.getCustomAttributes(context.getRootComponent())
                         .get(attribute));
         context = new DesignContext();
diff --git a/server/src/test/java/com/vaadin/tests/server/component/abstractorderedlayout/LayoutSettingsOnReplaceTest.java b/server/src/test/java/com/vaadin/tests/server/component/abstractorderedlayout/LayoutSettingsOnReplaceTest.java
index 79164dabd7..39d3a00d50 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/abstractorderedlayout/LayoutSettingsOnReplaceTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/abstractorderedlayout/LayoutSettingsOnReplaceTest.java
@@ -15,7 +15,8 @@
  */
 package com.vaadin.tests.server.component.abstractorderedlayout;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+
 import org.junit.Test;
 
 import com.vaadin.ui.AbstractComponent;
@@ -52,7 +53,7 @@ public class LayoutSettingsOnReplaceTest {
         };
         layout.replaceComponent(first, replace);
 
-        Assert.assertEquals(
+        assertEquals(
                 "Expand ratio for replaced component is not "
                         + "the same as for previous one",
                 ratio, layout.getExpandRatio(replace), 0.0001);
@@ -79,7 +80,7 @@ public class LayoutSettingsOnReplaceTest {
         };
         layout.replaceComponent(first, replace);
 
-        Assert.assertEquals(
+        assertEquals(
                 "Alignment for replaced component is not "
                         + "the same as for previous one",
                 alignment, layout.getComponentAlignment(replace));
diff --git a/server/src/test/java/com/vaadin/tests/server/component/abstractsinglecomponentcontainer/RemoveFromParentLockingTest.java b/server/src/test/java/com/vaadin/tests/server/component/abstractsinglecomponentcontainer/RemoveFromParentLockingTest.java
index f963152960..6295b9a0e7 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/abstractsinglecomponentcontainer/RemoveFromParentLockingTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/abstractsinglecomponentcontainer/RemoveFromParentLockingTest.java
@@ -15,8 +15,9 @@
  */
 package com.vaadin.tests.server.component.abstractsinglecomponentcontainer;
 
+import static org.junit.Assert.assertEquals;
+
 import org.junit.After;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -66,7 +67,7 @@ public class RemoveFromParentLockingTest {
             throw new AssertionError(
                     "Moving component when not holding its sessions's lock should throw");
         } catch (IllegalStateException e) {
-            Assert.assertEquals(
+            assertEquals(
                     "Cannot remove from parent when the session is not locked.",
                     e.getMessage());
         }
@@ -99,7 +100,7 @@ public class RemoveFromParentLockingTest {
             throw new AssertionError(
                     "Moving component when not holding its sessions's lock should throw");
         } catch (IllegalStateException e) {
-            Assert.assertEquals(
+            assertEquals(
                     "Cannot remove from parent when the session is not locked."
                             + " Furthermore, there is another locked session, indicating that the component might be about to be moved from one session to another.",
                     e.getMessage());
diff --git a/server/src/test/java/com/vaadin/tests/server/component/abstractsingleselect/AbstractSingleSelectDeclarativeTest.java b/server/src/test/java/com/vaadin/tests/server/component/abstractsingleselect/AbstractSingleSelectDeclarativeTest.java
index 6e46658b86..9dcbb31246 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/abstractsingleselect/AbstractSingleSelectDeclarativeTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/abstractsingleselect/AbstractSingleSelectDeclarativeTest.java
@@ -64,7 +64,7 @@ public abstract class AbstractSingleSelectDeclarativeTest<T extends AbstractSing
         component.setSelectedItem("bar");
 
         DesignContext context = readComponentAndCompare(design, component);
-        Assert.assertEquals(type,
+        assertEquals(type,
                 context.getCustomAttributes(context.getRootComponent())
                         .get(attribute));
         context = new DesignContext();
@@ -93,7 +93,7 @@ public abstract class AbstractSingleSelectDeclarativeTest<T extends AbstractSing
         component.setValue("bar");
 
         DesignContext context = readComponentAndCompare(design, component);
-        Assert.assertEquals(type,
+        assertEquals(type,
                 context.getCustomAttributes(context.getRootComponent())
                         .get(attribute));
         context = new DesignContext();
diff --git a/server/src/test/java/com/vaadin/tests/server/component/audio/AudioStateTest.java b/server/src/test/java/com/vaadin/tests/server/component/audio/AudioStateTest.java
index d96b6b3bc9..89dc4f547c 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/audio/AudioStateTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/audio/AudioStateTest.java
@@ -15,7 +15,8 @@
  */
 package com.vaadin.tests.server.component.audio;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+
 import org.junit.Test;
 
 import com.vaadin.shared.ui.audio.AudioState;
@@ -30,7 +31,7 @@ public class AudioStateTest {
     public void getState_audioHasCustomState() {
         TestAudio audio = new TestAudio();
         AudioState state = audio.getState();
-        Assert.assertEquals("Unexpected state class", AudioState.class,
+        assertEquals("Unexpected state class", AudioState.class,
                 state.getClass());
     }
 
@@ -38,14 +39,14 @@ public class AudioStateTest {
     public void getPrimaryStyleName_audioHasCustomPrimaryStyleName() {
         Audio audio = new Audio();
         AudioState state = new AudioState();
-        Assert.assertEquals("Unexpected primary style name",
-                state.primaryStyleName, audio.getPrimaryStyleName());
+        assertEquals("Unexpected primary style name", state.primaryStyleName,
+                audio.getPrimaryStyleName());
     }
 
     @Test
     public void audioStateHasCustomPrimaryStyleName() {
         AudioState state = new AudioState();
-        Assert.assertEquals("Unexpected primary style name", "v-audio",
+        assertEquals("Unexpected primary style name", "v-audio",
                 state.primaryStyleName);
     }
 
diff --git a/server/src/test/java/com/vaadin/tests/server/component/button/ButtonClickTest.java b/server/src/test/java/com/vaadin/tests/server/component/button/ButtonClickTest.java
index 00bba9cd1d..2adbfe2df8 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/button/ButtonClickTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/button/ButtonClickTest.java
@@ -1,8 +1,11 @@
 package com.vaadin.tests.server.component.button;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import java.util.concurrent.atomic.AtomicInteger;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.server.VaadinRequest;
@@ -25,13 +28,13 @@ public class ButtonClickTest {
         });
 
         b.click();
-        Assert.assertEquals(1, counter.get());
+        assertEquals(1, counter.get());
     }
 
     @Test
     public void testClick() {
         getButton().click();
-        Assert.assertTrue("Button doesn't fire clicks", clicked);
+        assertTrue("Button doesn't fire clicks", clicked);
     }
 
     @Test
@@ -39,7 +42,7 @@ public class ButtonClickTest {
         Button b = getButton();
         b.setEnabled(false);
         b.click();
-        Assert.assertFalse("Disabled button fires click events", clicked);
+        assertFalse("Disabled button fires click events", clicked);
     }
 
     private Button getButton() {
diff --git a/server/src/test/java/com/vaadin/tests/server/component/button/ButtonDeclarativeTest.java b/server/src/test/java/com/vaadin/tests/server/component/button/ButtonDeclarativeTest.java
index 70f93e7cff..408a7ca3b1 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/button/ButtonDeclarativeTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/button/ButtonDeclarativeTest.java
@@ -81,23 +81,23 @@ public class ButtonDeclarativeTest extends DeclarativeTestBase<Button> {
         String expectedCaptionPlainText = "> One";
 
         Button read = read(designPlainText);
-        Assert.assertEquals(expectedCaptionPlainText, read.getCaption());
+        assertEquals(expectedCaptionPlainText, read.getCaption());
 
         designPlainText = designPlainText.replace("vaadin-button",
                 "vaadin-native-button");
         Button nativeButton = read(designPlainText);
-        Assert.assertEquals(expectedCaptionPlainText,
+        assertEquals(expectedCaptionPlainText,
                 nativeButton.getCaption());
 
         String designHtml = "<vaadin-button>&gt; One</vaadin-button>";
         String expectedCaptionHtml = "&gt; One";
         read = read(designHtml);
-        Assert.assertEquals(expectedCaptionHtml, read.getCaption());
+        assertEquals(expectedCaptionHtml, read.getCaption());
 
         designHtml = designHtml.replace("vaadin-button",
                 "vaadin-native-button");
         nativeButton = read(designHtml);
-        Assert.assertEquals(expectedCaptionHtml, nativeButton.getCaption());
+        assertEquals(expectedCaptionHtml, nativeButton.getCaption());
 
         read = new Button("&amp; Test");
         read.setCaptionAsHtml(true);
diff --git a/server/src/test/java/com/vaadin/tests/server/component/combobox/ComboBoxFilteringTest.java b/server/src/test/java/com/vaadin/tests/server/component/combobox/ComboBoxFilteringTest.java
index 35c28eba17..9db40d2ed6 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/combobox/ComboBoxFilteringTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/combobox/ComboBoxFilteringTest.java
@@ -15,13 +15,15 @@
  */
 package com.vaadin.tests.server.component.combobox;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertSame;
+
 import java.util.Collections;
 import java.util.List;
 import java.util.Locale;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -42,8 +44,8 @@ import com.vaadin.ui.ComboBox;
  * @author Vaadin Ltd
  */
 public class ComboBoxFilteringTest {
-    private static final String[] PERSON_NAMES = {
-            "Enrique Iglesias", "Henry Dunant", "Erwin Engelbrecht" };
+    private static final String[] PERSON_NAMES = { "Enrique Iglesias",
+            "Henry Dunant", "Erwin Engelbrecht" };
 
     private ComboBox<Person> comboBox;
 
@@ -196,28 +198,26 @@ public class ComboBoxFilteringTest {
 
         comboBox.setDataProvider(provider);
 
-        Assert.assertSame(provider, comboBox.getDataProvider());
+        assertSame(provider, comboBox.getDataProvider());
     }
 
     @Test
     public void setItems_hasListDataProvider() {
         comboBox.setItems();
 
-        Assert.assertEquals(ListDataProvider.class,
+        assertEquals(ListDataProvider.class,
                 comboBox.getDataProvider().getClass());
     }
 
     private void checkFiltering(String filterText, String nonMatchingFilterText,
             int totalMatches, int matchingResults) {
-        Assert.assertEquals(
-                "ComboBox filtered out results with no filter applied",
+        assertEquals("ComboBox filtered out results with no filter applied",
                 totalMatches, comboBoxSizeWithFilter(null));
-        Assert.assertEquals(
-                "ComboBox filtered out results with empty filter string",
+        assertEquals("ComboBox filtered out results with empty filter string",
                 totalMatches, comboBoxSizeWithFilter(""));
-        Assert.assertEquals("ComboBox filtered out wrong number of results",
+        assertEquals("ComboBox filtered out wrong number of results",
                 matchingResults, comboBoxSizeWithFilter(filterText));
-        Assert.assertEquals(
+        assertEquals(
                 "ComboBox should have no results with a non-matching filter", 0,
                 comboBoxSizeWithFilter(nonMatchingFilterText));
     }
diff --git a/server/src/test/java/com/vaadin/tests/server/component/customlayout/CustomLayoutTest.java b/server/src/test/java/com/vaadin/tests/server/component/customlayout/CustomLayoutTest.java
index 9d60628e12..8ebc620328 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/customlayout/CustomLayoutTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/customlayout/CustomLayoutTest.java
@@ -15,6 +15,10 @@
  */
 package com.vaadin.tests.server.component.customlayout;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
 import java.io.ByteArrayInputStream;
 import java.io.FilterInputStream;
 import java.io.IOException;
@@ -26,7 +30,6 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Locale;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.ui.CustomLayout;
@@ -52,9 +55,9 @@ public class CustomLayoutTest {
         InputStreamImpl stream = new InputStreamImpl(inputStream, buffer / 2);
         new CustomLayout(stream);
 
-        Assert.assertTrue("Stream is not closed in CustomLayout CTOR ",
+        assertTrue("Stream is not closed in CustomLayout CTOR ",
                 stream.isClosed());
-        Assert.assertEquals("Number of read bytes is incorrect", bytes.length,
+        assertEquals("Number of read bytes is incorrect", bytes.length,
                 stream.getCount());
     }
 
@@ -78,7 +81,7 @@ public class CustomLayoutTest {
                 }
             }
         }
-        Assert.assertNotNull(
+        assertNotNull(
                 "Unable to find default buffer size in CustomLayout class",
                 field);
         field.setAccessible(true);
diff --git a/server/src/test/java/com/vaadin/tests/server/component/grid/EditorImplTest.java b/server/src/test/java/com/vaadin/tests/server/component/grid/EditorImplTest.java
index 61fd282edf..d85f9028c8 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/grid/EditorImplTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/grid/EditorImplTest.java
@@ -15,11 +15,13 @@
  */
 package com.vaadin.tests.server.component.grid;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
 import java.util.Optional;
 import java.util.stream.Stream;
 
-import com.vaadin.ui.Grid;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.Mockito;
@@ -29,6 +31,7 @@ import com.vaadin.data.PropertyDefinition;
 import com.vaadin.data.PropertySet;
 import com.vaadin.shared.communication.ServerRpc;
 import com.vaadin.shared.ui.grid.editor.EditorServerRpc;
+import com.vaadin.ui.Grid;
 import com.vaadin.ui.components.grid.EditorCancelEvent;
 import com.vaadin.ui.components.grid.EditorCancelListener;
 import com.vaadin.ui.components.grid.EditorImpl;
@@ -87,13 +90,13 @@ public class EditorImplTest {
 
         @Override
         public void onEditorCancel(EditorCancelEvent<Object> event) {
-            Assert.assertNull(cancelEvent);
+            assertNull(cancelEvent);
             cancelEvent = event;
         }
 
         @Override
         public void onEditorSave(EditorSaveEvent<Object> event) {
-            Assert.assertNull(saveEvent);
+            assertNull(saveEvent);
             saveEvent = event;
         }
 
@@ -128,23 +131,23 @@ public class EditorImplTest {
 
         editor.save();
 
-        Assert.assertNotNull(editor.saveEvent);
-        Assert.assertNull(editor.cancelEvent);
+        assertNotNull(editor.saveEvent);
+        assertNull(editor.cancelEvent);
 
-        Assert.assertEquals(editor, editor.saveEvent.getSource());
-        Assert.assertEquals(beanToEdit, editor.saveEvent.getBean());
+        assertEquals(editor, editor.saveEvent.getSource());
+        assertEquals(beanToEdit, editor.saveEvent.getBean());
     }
 
     @Test
     public void cancel_eventIsFired() {
         editor.cancel();
 
-        Assert.assertNull(editor.saveEvent);
-        Assert.assertNotNull(editor.cancelEvent);
+        assertNull(editor.saveEvent);
+        assertNotNull(editor.cancelEvent);
 
-        Assert.assertEquals(editor, editor.cancelEvent.getSource());
+        assertEquals(editor, editor.cancelEvent.getSource());
 
-        Assert.assertEquals(beanToEdit, editor.cancelEvent.getBean());
+        assertEquals(beanToEdit, editor.cancelEvent.getBean());
     }
 
     @Test
@@ -153,31 +156,31 @@ public class EditorImplTest {
 
         editor.rpc.save();
 
-        Assert.assertNotNull(editor.saveEvent);
-        Assert.assertNull(editor.cancelEvent);
+        assertNotNull(editor.saveEvent);
+        assertNull(editor.cancelEvent);
 
-        Assert.assertEquals(editor, editor.saveEvent.getSource());
+        assertEquals(editor, editor.saveEvent.getSource());
 
-        Assert.assertEquals(beanToEdit, editor.saveEvent.getBean());
+        assertEquals(beanToEdit, editor.saveEvent.getBean());
     }
 
     @Test
     public void cancelFromClient_eventIsFired() {
         editor.rpc.cancel(false);
 
-        Assert.assertNull(editor.saveEvent);
-        Assert.assertNotNull(editor.cancelEvent);
+        assertNull(editor.saveEvent);
+        assertNotNull(editor.cancelEvent);
 
-        Assert.assertEquals(editor, editor.cancelEvent.getSource());
+        assertEquals(editor, editor.cancelEvent.getSource());
 
-        Assert.assertEquals(beanToEdit, editor.cancelEvent.getBean());
+        assertEquals(beanToEdit, editor.cancelEvent.getBean());
     }
 
     @Test
     public void cancelAfterSaveFromClient_eventIsNotFired() {
         editor.rpc.cancel(true);
 
-        Assert.assertNull(editor.saveEvent);
-        Assert.assertNull(editor.cancelEvent);
+        assertNull(editor.saveEvent);
+        assertNull(editor.cancelEvent);
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/server/component/grid/GridChildrenTest.java b/server/src/test/java/com/vaadin/tests/server/component/grid/GridChildrenTest.java
index 97cfe6ebc7..6a8e329f20 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/grid/GridChildrenTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/grid/GridChildrenTest.java
@@ -15,9 +15,12 @@
  */
 package com.vaadin.tests.server.component.grid;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+
 import java.util.Iterator;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -48,8 +51,8 @@ public class GridChildrenTest {
         Label label = new Label();
         merged.setComponent(label);
         Iterator<Component> i = grid.iterator();
-        Assert.assertEquals(label, i.next());
-        Assert.assertFalse(i.hasNext());
+        assertEquals(label, i.next());
+        assertFalse(i.hasNext());
     }
 
     @Test
@@ -58,9 +61,9 @@ public class GridChildrenTest {
                 "baz");
         Label label = new Label();
         merged.setComponent(label);
-        Assert.assertEquals(grid, label.getParent());
+        assertEquals(grid, label.getParent());
         merged.setText("foo");
-        Assert.assertNull(label.getParent());
+        assertNull(label.getParent());
     }
 
     @Test
@@ -69,9 +72,9 @@ public class GridChildrenTest {
                 "baz");
         Label label = new Label();
         merged.setComponent(label);
-        Assert.assertEquals(grid, label.getParent());
+        assertEquals(grid, label.getParent());
         grid.removeHeaderRow(0);
-        Assert.assertNull(label.getParent());
+        assertNull(label.getParent());
     }
 
     @Test
@@ -79,9 +82,9 @@ public class GridChildrenTest {
         FooterCell merged = grid.addFooterRowAt(0).join("foo", "bar", "baz");
         Label label = new Label();
         merged.setComponent(label);
-        Assert.assertEquals(grid, label.getParent());
+        assertEquals(grid, label.getParent());
         merged.setText("foo");
-        Assert.assertNull(label.getParent());
+        assertNull(label.getParent());
     }
 
     @Test
@@ -89,9 +92,9 @@ public class GridChildrenTest {
         FooterCell merged = grid.addFooterRowAt(0).join("foo", "bar", "baz");
         Label label = new Label();
         merged.setComponent(label);
-        Assert.assertEquals(grid, label.getParent());
+        assertEquals(grid, label.getParent());
         grid.removeFooterRow(0);
-        Assert.assertNull(label.getParent());
+        assertNull(label.getParent());
     }
 
     @Test
@@ -100,8 +103,8 @@ public class GridChildrenTest {
         Label label = new Label();
         merged.setComponent(label);
         Iterator<Component> i = grid.iterator();
-        Assert.assertEquals(label, i.next());
-        Assert.assertFalse(i.hasNext());
-        Assert.assertEquals(grid, label.getParent());
+        assertEquals(label, i.next());
+        assertFalse(i.hasNext());
+        assertEquals(grid, label.getParent());
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/server/component/grid/GridCustomPropertySetTest.java b/server/src/test/java/com/vaadin/tests/server/component/grid/GridCustomPropertySetTest.java
index c1726d77ba..ba773ca68d 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/grid/GridCustomPropertySetTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/grid/GridCustomPropertySetTest.java
@@ -15,10 +15,11 @@
  */
 package com.vaadin.tests.server.component.grid;
 
+import static org.junit.Assert.assertEquals;
+
 import java.util.Optional;
 import java.util.stream.Stream;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.data.PropertyDefinition;
@@ -166,20 +167,20 @@ public class GridCustomPropertySetTest {
     @Test
     public void customPropertySet() {
         GridWithCustomPropertySet customGrid = new GridWithCustomPropertySet();
-        Assert.assertEquals(0, customGrid.getColumns().size());
+        assertEquals(0, customGrid.getColumns().size());
 
         Column<MyBeanWithoutGetters, Integer> numberColumn = (Column<MyBeanWithoutGetters, Integer>) customGrid
                 .addColumn("numbah");
-        Assert.assertEquals(1, customGrid.getColumns().size());
-        Assert.assertEquals("The Number", numberColumn.getCaption());
-        Assert.assertEquals(24, (int) numberColumn.getValueProvider()
+        assertEquals(1, customGrid.getColumns().size());
+        assertEquals("The Number", numberColumn.getCaption());
+        assertEquals(24, (int) numberColumn.getValueProvider()
                 .apply(new MyBeanWithoutGetters("foo", 24)));
 
         Column<MyBeanWithoutGetters, String> stringColumn = (Column<MyBeanWithoutGetters, String>) customGrid
                 .addColumn("string");
-        Assert.assertEquals(2, customGrid.getColumns().size());
-        Assert.assertEquals("The String", stringColumn.getCaption());
-        Assert.assertEquals("foo", stringColumn.getValueProvider()
+        assertEquals(2, customGrid.getColumns().size());
+        assertEquals("The String", stringColumn.getCaption());
+        assertEquals("foo", stringColumn.getValueProvider()
                 .apply(new MyBeanWithoutGetters("foo", 24)));
     }
 
diff --git a/server/src/test/java/com/vaadin/tests/server/component/grid/GridDeclarativeTest.java b/server/src/test/java/com/vaadin/tests/server/component/grid/GridDeclarativeTest.java
index 52af306ec5..8d1d6c6955 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/grid/GridDeclarativeTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/grid/GridDeclarativeTest.java
@@ -15,6 +15,8 @@
  */
 package com.vaadin.tests.server.component.grid;
 
+import static org.junit.Assert.assertNull;
+
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.util.List;
@@ -26,7 +28,6 @@ import org.jsoup.nodes.Element;
 import org.jsoup.parser.Tag;
 import org.jsoup.select.Elements;
 import org.jsoup.select.Selector;
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.data.SelectionModel.Multi;
@@ -109,19 +110,17 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
         String headerRowText3 = "foobar";
         join.setText(headerRowText3);
 
-        String design = String.format(
-                "<%s><table><colgroup>" + "<col column-id='column0' sortable>"
-                        + "<col column-id='id' sortable>"
-                        + "<col column-id='mail' sortable>"
-                        + "</colgroup><thead>"
-                        + "<tr default><th plain-text column-ids='column0'>First Name</th>"
-                        + "<th plain-text column-ids='id'>Id</th>"
-                        + "<th plain-text column-ids='mail'>Mail</th></tr>"
-                        + "<tr><th plain-text column-ids='column0'>%s</th>"
-                        + "<th colspan='2' plain-text column-ids='id,mail'>foobar</th></tr>"
-                        + "</thead></table></%s>",
-                getComponentTag(), headerRowText1, headerRowText3,
-                getComponentTag());
+        String design = String.format("<%s><table><colgroup>"
+                + "<col column-id='column0' sortable>"
+                + "<col column-id='id' sortable>"
+                + "<col column-id='mail' sortable>" + "</colgroup><thead>"
+                + "<tr default><th plain-text column-ids='column0'>First Name</th>"
+                + "<th plain-text column-ids='id'>Id</th>"
+                + "<th plain-text column-ids='mail'>Mail</th></tr>"
+                + "<tr><th plain-text column-ids='column0'>%s</th>"
+                + "<th colspan='2' plain-text column-ids='id,mail'>foobar</th></tr>"
+                + "</thead></table></%s>", getComponentTag(), headerRowText1,
+                headerRowText3, getComponentTag());
 
         testRead(design, grid);
         testWrite(design, grid);
@@ -150,19 +149,17 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
         String footerRowText2 = "foobar";
         footer.join(cell2, cell3).setHtml(footerRowText2);
 
-        String design = String.format(
-                "<%s><table><colgroup>" + "<col column-id='column0' sortable>"
-                        + "<col column-id='id' sortable>"
-                        + "<col column-id='mail' sortable>"
-                        + "</colgroup><thead>"
-                        + "<tr default><th plain-text column-ids='column0'>First Name</th>"
-                        + "<th plain-text column-ids='id'>Id</th>"
-                        + "<th plain-text column-ids='mail'>Mail</th></tr></thead>"
-                        + "<tfoot><tr><td plain-text column-ids='column0'>%s</td>"
-                        + "<td colspan='2' column-ids='id,mail'>%s</td></tr></tfoot>"
-                        + "</table></%s>",
-                getComponentTag(), footerRowText1, footerRowText2,
-                getComponentTag());
+        String design = String.format("<%s><table><colgroup>"
+                + "<col column-id='column0' sortable>"
+                + "<col column-id='id' sortable>"
+                + "<col column-id='mail' sortable>" + "</colgroup><thead>"
+                + "<tr default><th plain-text column-ids='column0'>First Name</th>"
+                + "<th plain-text column-ids='id'>Id</th>"
+                + "<th plain-text column-ids='mail'>Mail</th></tr></thead>"
+                + "<tfoot><tr><td plain-text column-ids='column0'>%s</td>"
+                + "<td colspan='2' column-ids='id,mail'>%s</td></tr></tfoot>"
+                + "</table></%s>", getComponentTag(), footerRowText1,
+                footerRowText2, getComponentTag());
 
         testRead(design, grid);
         testWrite(design, grid);
@@ -203,17 +200,15 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
         int expandRatio = 83;
         column2.setExpandRatio(expandRatio);
 
-        String design = String.format(
-                "<%s><table><colgroup>"
-                        + "<col column-id='column0' sortable='%s' editable resizable='%s' hidable hidden>"
-                        + "<col column-id='id' sortable hiding-toggle-caption='%s' width='%s' min-width='%s' max-width='%s' expand='%s'>"
-                        + "</colgroup><thead>"
-                        + "<tr default><th plain-text column-ids='column0'>%s</th>"
-                        + "<th plain-text column-ids='id'>%s</th>"
-                        + "</tr></thead>" + "</table></%s>",
-                getComponentTag(), sortable, resizable, hidingToggleCaption,
-                width, minWidth, maxWidth, expandRatio, caption, "Id",
-                getComponentTag());
+        String design = String.format("<%s><table><colgroup>"
+                + "<col column-id='column0' sortable='%s' editable resizable='%s' hidable hidden>"
+                + "<col column-id='id' sortable hiding-toggle-caption='%s' width='%s' min-width='%s' max-width='%s' expand='%s'>"
+                + "</colgroup><thead>"
+                + "<tr default><th plain-text column-ids='column0'>%s</th>"
+                + "<th plain-text column-ids='id'>%s</th>" + "</tr></thead>"
+                + "</table></%s>", getComponentTag(), sortable, resizable,
+                hidingToggleCaption, width, minWidth, maxWidth, expandRatio,
+                caption, "Id", getComponentTag());
 
         testRead(design, grid, true);
         testWrite(design, grid);
@@ -232,15 +227,14 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
         footerRow.getCell(column1).setText("x");
         footerRow.getCell(column2).setHtml("y");
 
-        String design = String.format(
-                "<%s><table><colgroup>" + "<col column-id='column0' sortable>"
-                        + "<col column-id='id' sortable></colgroup><thead>"
-                        + "<tr default><th plain-text column-ids='column0'>First Name</th>"
-                        + "<th plain-text column-ids='id'>Id</th></tr>"
-                        + "</thead><tbody></tbody>"
-                        + "<tfoot><tr><td plain-text column-ids='column0'>x</td>"
-                        + "<td column-ids='id'>y</td></tr></tfoot>"
-                        + "</table></%s>",
+        String design = String.format("<%s><table><colgroup>"
+                + "<col column-id='column0' sortable>"
+                + "<col column-id='id' sortable></colgroup><thead>"
+                + "<tr default><th plain-text column-ids='column0'>First Name</th>"
+                + "<th plain-text column-ids='id'>Id</th></tr>"
+                + "</thead><tbody></tbody>"
+                + "<tfoot><tr><td plain-text column-ids='column0'>x</td>"
+                + "<td column-ids='id'>y</td></tr></tfoot>" + "</table></%s>",
                 getComponentTag(), getComponentTag());
 
         testRead(design, grid);
@@ -259,22 +253,22 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
         grid.addColumn(Person::getFirstName).setCaption("First Name");
         grid.addColumn(Person::getLastName).setId("id").setCaption("Id");
 
-        String design = String.format(
-                "<%s><table><colgroup>" + "<col column-id='column0' sortable>"
-                        + "<col column-id='id' sortable></colgroup><thead>"
-                        + "<tr default><th plain-text column-ids='column0'>First Name</th>"
-                        + "<th plain-text column-ids='id'>Id</th></tr>"
-                        + "</thead><tbody>"
-                        + "<tr item='%s'><td>%s</td><td>%s</td></tr>"
-                        + "<tr item='%s'><td>%s</td><td>%s</td></tr>"
-                        + "</tbody></table></%s>",
-                getComponentTag(), person1.toString(), person1.getFirstName(),
+        String design = String.format("<%s><table><colgroup>"
+                + "<col column-id='column0' sortable>"
+                + "<col column-id='id' sortable></colgroup><thead>"
+                + "<tr default><th plain-text column-ids='column0'>First Name</th>"
+                + "<th plain-text column-ids='id'>Id</th></tr>"
+                + "</thead><tbody>"
+                + "<tr item='%s'><td>%s</td><td>%s</td></tr>"
+                + "<tr item='%s'><td>%s</td><td>%s</td></tr>"
+                + "</tbody></table></%s>", getComponentTag(),
+                person1.toString(), person1.getFirstName(),
                 person1.getLastName(), person2.toString(),
                 person2.getFirstName(), person2.getLastName(),
                 getComponentTag());
 
         Grid<?> readGrid = testRead(design, grid, true, true);
-        Assert.assertEquals(2, readGrid.getDataProvider().size(new Query<>()));
+        assertEquals(2, readGrid.getDataProvider().size(new Query<>()));
         testWrite(design, grid, true);
     }
 
@@ -324,7 +318,7 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
                 person3.getLastName(), getComponentTag());
 
         Grid<?> readGrid = testRead(design, grid, true, true);
-        Assert.assertEquals(3, readGrid.getDataProvider().size(new Query<>()));
+        assertEquals(3, readGrid.getDataProvider().size(new Query<>()));
         testWrite(design, grid, true);
     }
 
@@ -344,22 +338,22 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
                 .setSelectionMode(SelectionMode.SINGLE);
         model.select(person2);
 
-        String design = String.format(
-                "<%s><table><colgroup>" + "<col column-id='column0' sortable>"
-                        + "<col column-id='id' sortable></colgroup><thead>"
-                        + "<tr default><th plain-text column-ids='column0'>First Name</th>"
-                        + "<th plain-text column-ids='id'>Id</th></tr>"
-                        + "</thead><tbody>"
-                        + "<tr item='%s'><td>%s</td><td>%s</td></tr>"
-                        + "<tr item='%s' selected><td>%s</td><td>%s</td></tr>"
-                        + "</tbody></table></%s>",
-                getComponentTag(), person1.toString(), person1.getFirstName(),
+        String design = String.format("<%s><table><colgroup>"
+                + "<col column-id='column0' sortable>"
+                + "<col column-id='id' sortable></colgroup><thead>"
+                + "<tr default><th plain-text column-ids='column0'>First Name</th>"
+                + "<th plain-text column-ids='id'>Id</th></tr>"
+                + "</thead><tbody>"
+                + "<tr item='%s'><td>%s</td><td>%s</td></tr>"
+                + "<tr item='%s' selected><td>%s</td><td>%s</td></tr>"
+                + "</tbody></table></%s>", getComponentTag(),
+                person1.toString(), person1.getFirstName(),
                 person1.getLastName(), person2.toString(),
                 person2.getFirstName(), person2.getLastName(),
                 getComponentTag());
 
         Grid<?> readGrid = testRead(design, grid, true, true);
-        Assert.assertEquals(2, readGrid.getDataProvider().size(new Query<>()));
+        assertEquals(2, readGrid.getDataProvider().size(new Query<>()));
         testWrite(design, grid, true);
     }
 
@@ -395,7 +389,7 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
                 person2.getLastName(), getComponentTag());
 
         Grid<?> readGrid = testRead(design, grid, true, true);
-        Assert.assertEquals(2, readGrid.getDataProvider().size(new Query<>()));
+        assertEquals(2, readGrid.getDataProvider().size(new Query<>()));
         testWrite(design, grid, true);
 
         grid.setSelectionMode(SelectionMode.SINGLE);
@@ -408,7 +402,7 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
                 getComponentTag());
 
         readGrid = testRead(design, grid, true, true);
-        Assert.assertEquals(2, readGrid.getDataProvider().size(new Query<>()));
+        assertEquals(2, readGrid.getDataProvider().size(new Query<>()));
         testWrite(design, grid, true);
     }
 
@@ -540,8 +534,8 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
         String actualFooter = grid.getFooterRow(0).getCell(id).getText();
         String expected = "> Test";
 
-        Assert.assertEquals(expected, actualHeader);
-        Assert.assertEquals(expected, actualFooter);
+        assertEquals(expected, actualHeader);
+        assertEquals(expected, actualFooter);
 
         design = design.replace(plainText, "");
         grid = read(design);
@@ -549,8 +543,8 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
         actualFooter = grid.getFooterRow(0).getCell(id).getHtml();
         expected = "&gt; Test";
 
-        Assert.assertEquals(expected, actualHeader);
-        Assert.assertEquals(expected, actualFooter);
+        assertEquals(expected, actualHeader);
+        assertEquals(expected, actualFooter);
 
         grid = new Grid<>();
         Column<Person, String> column = grid.addColumn(Person::getFirstName)
@@ -566,9 +560,9 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
         Element root = new Element(Tag.valueOf(getComponentTag()), "");
         grid.writeDesign(root, new DesignContext());
 
-        Assert.assertEquals("&amp;amp; Test",
+        assertEquals("&amp;amp; Test",
                 root.getElementsByTag("th").get(0).html());
-        Assert.assertEquals("&amp;amp; Test",
+        assertEquals("&amp;amp; Test",
                 root.getElementsByTag("td").get(0).html());
 
         header = grid.addHeaderRowAt(0);
@@ -581,10 +575,8 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
         root = new Element(Tag.valueOf(getComponentTag()), "");
         grid.writeDesign(root, new DesignContext());
 
-        Assert.assertEquals("&amp; Test",
-                root.getElementsByTag("th").get(0).html());
-        Assert.assertEquals("&amp; Test",
-                root.getElementsByTag("td").get(0).html());
+        assertEquals("&amp; Test", root.getElementsByTag("th").get(0).html());
+        assertEquals("&amp; Test", root.getElementsByTag("td").get(0).html());
 
     }
 
@@ -617,14 +609,14 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
     }
 
     private void compareHeaders(Grid<?> expected, Grid<?> actual) {
-        Assert.assertEquals("Different header row count",
-                expected.getHeaderRowCount(), actual.getHeaderRowCount());
+        assertEquals("Different header row count", expected.getHeaderRowCount(),
+                actual.getHeaderRowCount());
         for (int i = 0; i < expected.getHeaderRowCount(); ++i) {
             HeaderRow expectedRow = expected.getHeaderRow(i);
             HeaderRow actualRow = actual.getHeaderRow(i);
 
             if (expectedRow.equals(expected.getDefaultHeaderRow())) {
-                Assert.assertEquals("Different index for default header row",
+                assertEquals("Different index for default header row",
                         actual.getDefaultHeaderRow(), actualRow);
             }
 
@@ -636,11 +628,11 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
 
                 switch (expectedCell.getCellType()) {
                 case TEXT:
-                    Assert.assertEquals(baseError + "Text content",
+                    assertEquals(baseError + "Text content",
                             expectedCell.getText(), actualCell.getText());
                     break;
                 case HTML:
-                    Assert.assertEquals(baseError + "HTML content",
+                    assertEquals(baseError + "HTML content",
                             expectedCell.getHtml(), actualCell.getHtml());
                     break;
                 case WIDGET:
@@ -654,8 +646,8 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
     }
 
     private void compareFooters(Grid<?> expected, Grid<?> actual) {
-        Assert.assertEquals("Different footer row count",
-                expected.getFooterRowCount(), actual.getFooterRowCount());
+        assertEquals("Different footer row count", expected.getFooterRowCount(),
+                actual.getFooterRowCount());
         for (int i = 0; i < expected.getFooterRowCount(); ++i) {
             FooterRow expectedRow = expected.getFooterRow(i);
             FooterRow actualRow = actual.getFooterRow(i);
@@ -668,11 +660,11 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
 
                 switch (expectedCell.getCellType()) {
                 case TEXT:
-                    Assert.assertEquals(baseError + "Text content",
+                    assertEquals(baseError + "Text content",
                             expectedCell.getText(), actualCell.getText());
                     break;
                 case HTML:
-                    Assert.assertEquals(baseError + "HTML content",
+                    assertEquals(baseError + "HTML content",
                             expectedCell.getHtml(), actualCell.getHtml());
                     break;
                 case WIDGET:
@@ -688,7 +680,7 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
     private void compareGridColumns(Grid<?> expected, Grid<?> actual) {
         List<?> columns = expected.getColumns();
         List<?> actualColumns = actual.getColumns();
-        Assert.assertEquals("Different amount of columns", columns.size(),
+        assertEquals("Different amount of columns", columns.size(),
                 actualColumns.size());
         for (int i = 0; i < columns.size(); ++i) {
             Column<?, ?> col1 = (Column<?, ?>) columns.get(i);
@@ -762,7 +754,7 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
 
         @SuppressWarnings("unchecked")
         Grid<Person> grid = read(design);
-        Assert.assertEquals(beanClass, grid.getBeanType());
+        assertEquals(beanClass, grid.getBeanType());
 
         testWrite(design, grid);
     }
@@ -786,31 +778,29 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
         Document html = Jsoup.parse(design);
         Elements cols = Selector.select("vaadin-grid", html)
                 .select("colgroup > col");
-        Assert.assertEquals("Number of columns in the design file", i,
-                cols.size());
+        assertEquals("Number of columns in the design file", i, cols.size());
 
     }
 
     private void assertColumns(int expectedCount,
             List<Column<Person, ?>> expectedColumns,
             List<Column<Person, ?>> columns, Person testPerson) {
-        Assert.assertEquals(expectedCount, expectedColumns.size());
-        Assert.assertEquals(expectedCount, columns.size());
+        assertEquals(expectedCount, expectedColumns.size());
+        assertEquals(expectedCount, columns.size());
         for (int i = 0; i < expectedColumns.size(); i++) {
             Column<Person, ?> expectedColumn = expectedColumns.get(i);
             Column<Person, ?> column = columns.get(i);
 
             // Property mapping
-            Assert.assertEquals(expectedColumn.getId(), column.getId());
+            assertEquals(expectedColumn.getId(), column.getId());
             // Header caption
-            Assert.assertEquals(expectedColumn.getCaption(),
-                    column.getCaption());
+            assertEquals(expectedColumn.getCaption(), column.getCaption());
 
             // Value providers are not stored in the declarative file
             // so this only works for bean properties
             if (column.getId() != null
                     && !column.getId().equals("column" + i)) {
-                Assert.assertEquals(
+                assertEquals(
                         expectedColumn.getValueProvider().apply(testPerson),
                         column.getValueProvider().apply(testPerson));
             }
@@ -834,8 +824,8 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
         assertColumns(0, grid.getColumns(), readGrid.getColumns(), testPerson);
 
         // Can add a mapped property
-        Assert.assertEquals("The email", readGrid.addColumn("email")
-                .getValueProvider().apply(testPerson));
+        assertEquals("The email", readGrid.addColumn("email").getValueProvider()
+                .apply(testPerson));
     }
 
     @Test
@@ -856,11 +846,11 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
 
         assertColumns(1, grid.getColumns(), readGrid.getColumns(), testPerson);
         // First name should not be mapped to the property
-        Assert.assertNull(readGrid.getColumns().get(0).getValueProvider()
+        assertNull(readGrid.getColumns().get(0).getValueProvider()
                 .apply(testPerson));
 
         // Can add a mapped property
-        Assert.assertEquals("the last", readGrid.addColumn("lastName")
+        assertEquals("the last", readGrid.addColumn("lastName")
                 .getValueProvider().apply(testPerson));
     }
 
@@ -882,7 +872,7 @@ public class GridDeclarativeTest extends AbstractListingDeclarativeTest<Grid> {
 
         assertColumns(12, grid.getColumns(), readGrid.getColumns(), testPerson);
         // First and last name should not be mapped to anything but should exist
-        Assert.assertNull(readGrid.getColumns().get(11).getValueProvider()
+        assertNull(readGrid.getColumns().get(11).getValueProvider()
                 .apply(testPerson));
 
     }
diff --git a/server/src/test/java/com/vaadin/tests/server/component/grid/GridDetailsTest.java b/server/src/test/java/com/vaadin/tests/server/component/grid/GridDetailsTest.java
index 454b5d3b3d..08abc4b7b4 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/grid/GridDetailsTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/grid/GridDetailsTest.java
@@ -1,11 +1,14 @@
 package com.vaadin.tests.server.component.grid;
 
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Iterator;
 import java.util.List;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -57,13 +60,10 @@ public class GridDetailsTest {
         for (Component c : grid) {
             if (c instanceof Label) {
                 String value = ((Label) c).getValue();
-                Assert.assertTrue(
-                        "Unexpected label in component iterator with value "
-                                + value,
-                        data.remove(value));
+                assertTrue("Unexpected label in component iterator with value "
+                        + value, data.remove(value));
             } else {
-                Assert.fail(
-                        "Iterator contained a component that is not a label.");
+                fail("Iterator contained a component that is not a label.");
             }
         }
     }
@@ -78,10 +78,10 @@ public class GridDetailsTest {
 
     @Test
     public void testGridComponentIteratorIsEmptyAfterHidingDetails() {
-        Assert.assertTrue("Component iterator should have components.",
+        assertTrue("Component iterator should have components.",
                 grid.iterator().hasNext());
         data.forEach(s -> grid.setDetailsVisible(s, false));
-        Assert.assertFalse("Component iterator should not have components.",
+        assertFalse("Component iterator should not have components.",
                 grid.iterator().hasNext());
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/server/component/grid/GridTest.java b/server/src/test/java/com/vaadin/tests/server/component/grid/GridTest.java
index 5f8327bb8d..cb0459dc90 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/grid/GridTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/grid/GridTest.java
@@ -1,8 +1,12 @@
 package com.vaadin.tests.server.component.grid;
 
+import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
 
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
@@ -23,15 +27,14 @@ import java.util.concurrent.atomic.AtomicReference;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
-import com.vaadin.data.provider.DataCommunicator;
 import org.easymock.Capture;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
 import com.vaadin.data.Binder.Binding;
 import com.vaadin.data.ValidationException;
 import com.vaadin.data.ValueProvider;
+import com.vaadin.data.provider.DataCommunicator;
 import com.vaadin.data.provider.DataGenerator;
 import com.vaadin.data.provider.GridSortOrder;
 import com.vaadin.data.provider.QuerySortOrder;
@@ -75,7 +78,8 @@ public class GridTest {
     public void testCreateGridWithDataCommunicator() {
         DataCommunicator specificDataCommunicator = new DataCommunicator<>();
 
-        TestGrid<String> grid = new TestGrid(String.class, specificDataCommunicator);
+        TestGrid<String> grid = new TestGrid(String.class,
+                specificDataCommunicator);
 
         assertEquals(specificDataCommunicator, grid.getDataCommunicator());
     }
@@ -184,7 +188,7 @@ public class GridTest {
         assertEquals("foo", event.getFirstSelectedItem().get());
         assertEquals("foo",
                 event.getAllSelectedItems().stream().findFirst().get());
-        Assert.assertArrayEquals(new String[] { "foo", "bar" },
+        assertArrayEquals(new String[] { "foo", "bar" },
                 event.getAllSelectedItems().toArray(new String[2]));
 
         grid.getSelectionModel().deselect("foo");
@@ -195,7 +199,7 @@ public class GridTest {
         assertEquals("bar", event.getFirstSelectedItem().get());
         assertEquals("bar",
                 event.getAllSelectedItems().stream().findFirst().get());
-        Assert.assertArrayEquals(new String[] { "bar" },
+        assertArrayEquals(new String[] { "bar" },
                 event.getAllSelectedItems().toArray(new String[1]));
 
         grid.getSelectionModel().deselectAll();
@@ -211,8 +215,7 @@ public class GridTest {
     public void testAddSelectionListener_noSelectionMode() {
         grid.setSelectionMode(SelectionMode.NONE);
 
-        grid.addSelectionListener(
-                event -> Assert.fail("never ever happens (tm)"));
+        grid.addSelectionListener(event -> fail("never ever happens (tm)"));
     }
 
     @Test
@@ -221,8 +224,8 @@ public class GridTest {
         grid.sort(column);
 
         GridSortOrder<String> sortOrder = grid.getSortOrder().get(0);
-        Assert.assertEquals(column, sortOrder.getSorted());
-        Assert.assertEquals(SortDirection.ASCENDING, sortOrder.getDirection());
+        assertEquals(column, sortOrder.getSorted());
+        assertEquals(SortDirection.ASCENDING, sortOrder.getDirection());
     }
 
     @Test
@@ -231,8 +234,8 @@ public class GridTest {
         grid.sort(column, SortDirection.DESCENDING);
 
         GridSortOrder<String> sortOrder = grid.getSortOrder().get(0);
-        Assert.assertEquals(column, sortOrder.getSorted());
-        Assert.assertEquals(SortDirection.DESCENDING, sortOrder.getDirection());
+        assertEquals(column, sortOrder.getSorted());
+        assertEquals(SortDirection.DESCENDING, sortOrder.getDirection());
     }
 
     @Test
@@ -245,13 +248,11 @@ public class GridTest {
         grid.setSortOrder(order);
 
         List<GridSortOrder<String>> sortOrder = grid.getSortOrder();
-        Assert.assertEquals(column2, sortOrder.get(0).getSorted());
-        Assert.assertEquals(SortDirection.DESCENDING,
-                sortOrder.get(0).getDirection());
+        assertEquals(column2, sortOrder.get(0).getSorted());
+        assertEquals(SortDirection.DESCENDING, sortOrder.get(0).getDirection());
 
-        Assert.assertEquals(column1, sortOrder.get(1).getSorted());
-        Assert.assertEquals(SortDirection.ASCENDING,
-                sortOrder.get(1).getDirection());
+        assertEquals(column1, sortOrder.get(1).getSorted());
+        assertEquals(SortDirection.ASCENDING, sortOrder.get(1).getDirection());
     }
 
     @Test
@@ -272,15 +273,14 @@ public class GridTest {
         List<GridSortOrder<String>> list = new ArrayList<>();
         AtomicReference<Boolean> fired = new AtomicReference<>();
         grid.addSortListener(event -> {
-            Assert.assertTrue(list.isEmpty());
+            assertTrue(list.isEmpty());
             fired.set(true);
             list.addAll(event.getSortOrder());
         });
         grid.sort(column1, SortDirection.DESCENDING);
 
-        Assert.assertEquals(column1, list.get(0).getSorted());
-        Assert.assertEquals(SortDirection.DESCENDING,
-                list.get(0).getDirection());
+        assertEquals(column1, list.get(0).getSorted());
+        assertEquals(SortDirection.DESCENDING, list.get(0).getDirection());
 
         List<GridSortOrder<String>> order = Arrays.asList(
                 new GridSortOrder<>(column2, SortDirection.DESCENDING),
@@ -289,19 +289,17 @@ public class GridTest {
 
         grid.setSortOrder(order);
 
-        Assert.assertEquals(column2, list.get(0).getSorted());
-        Assert.assertEquals(SortDirection.DESCENDING,
-                list.get(0).getDirection());
+        assertEquals(column2, list.get(0).getSorted());
+        assertEquals(SortDirection.DESCENDING, list.get(0).getDirection());
 
-        Assert.assertEquals(column1, list.get(1).getSorted());
-        Assert.assertEquals(SortDirection.ASCENDING,
-                list.get(1).getDirection());
+        assertEquals(column1, list.get(1).getSorted());
+        assertEquals(SortDirection.ASCENDING, list.get(1).getDirection());
 
         list.clear();
         fired.set(false);
         grid.clearSortOrder();
-        Assert.assertEquals(0, list.size());
-        Assert.assertTrue(fired.get());
+        assertEquals(0, list.size());
+        assertTrue(fired.get());
     }
 
     @Test
@@ -311,19 +309,18 @@ public class GridTest {
         Column<Person, ?> nameColumn = grid.getColumn("name");
         Column<Person, ?> bornColumn = grid.getColumn("born");
 
-        Assert.assertNotNull(nameColumn);
-        Assert.assertNotNull(bornColumn);
+        assertNotNull(nameColumn);
+        assertNotNull(bornColumn);
 
-        Assert.assertEquals("Name", nameColumn.getCaption());
-        Assert.assertEquals("Born", bornColumn.getCaption());
+        assertEquals("Name", nameColumn.getCaption());
+        assertEquals("Born", bornColumn.getCaption());
 
         JsonObject json = getRowData(grid, new Person("Lorem", 2000));
 
         Set<String> values = Stream.of(json.keys()).map(json::getString)
                 .collect(Collectors.toSet());
 
-        Assert.assertEquals(new HashSet<>(Arrays.asList("Lorem", "2000")),
-                values);
+        assertEquals(new HashSet<>(Arrays.asList("Lorem", "2000")), values);
 
         assertSingleSortProperty(nameColumn, "name");
         assertSingleSortProperty(bornColumn, "born");
@@ -340,18 +337,18 @@ public class GridTest {
 
         Optional<Binding<Person, ?>> maybeBinding = grid.getEditor().getBinder()
                 .getBinding("name");
-        Assert.assertTrue(maybeBinding.isPresent());
+        assertTrue(maybeBinding.isPresent());
 
         Binding<Person, ?> binding = maybeBinding.get();
-        Assert.assertSame(nameField, binding.getField());
+        assertSame(nameField, binding.getField());
 
         Person person = new Person("Lorem", 2000);
         grid.getEditor().getBinder().setBean(person);
 
-        Assert.assertEquals("Lorem", nameField.getValue());
+        assertEquals("Lorem", nameField.getValue());
 
         nameField.setValue("Ipsum");
-        Assert.assertEquals("Ipsum", person.getName());
+        assertEquals("Ipsum", person.getName());
     }
 
     @Test(expected = IllegalStateException.class)
@@ -377,17 +374,16 @@ public class GridTest {
         grid.addColumn("name");
 
         List<Column<Person, ?>> columns = grid.getColumns();
-        Assert.assertEquals(2, columns.size());
-        Assert.assertEquals("born", columns.get(0).getId());
-        Assert.assertEquals("name", columns.get(1).getId());
+        assertEquals(2, columns.size());
+        assertEquals("born", columns.get(0).getId());
+        assertEquals("name", columns.get(1).getId());
     }
 
     @Test
     public void removeColumnByColumn() {
         grid.removeColumn(fooColumn);
 
-        Assert.assertEquals(
-                Arrays.asList(lengthColumn, objectColumn, randomColumn),
+        assertEquals(Arrays.asList(lengthColumn, objectColumn, randomColumn),
                 grid.getColumns());
     }
 
@@ -397,8 +393,7 @@ public class GridTest {
         // Questionable that this doesn't throw, but that's a separate ticket...
         grid.removeColumn(fooColumn);
 
-        Assert.assertEquals(
-                Arrays.asList(lengthColumn, objectColumn, randomColumn),
+        assertEquals(Arrays.asList(lengthColumn, objectColumn, randomColumn),
                 grid.getColumns());
     }
 
@@ -412,8 +407,7 @@ public class GridTest {
     public void removeColumnById() {
         grid.removeColumn("foo");
 
-        Assert.assertEquals(
-                Arrays.asList(lengthColumn, objectColumn, randomColumn),
+        assertEquals(Arrays.asList(lengthColumn, objectColumn, randomColumn),
                 grid.getColumns());
     }
 
@@ -421,14 +415,14 @@ public class GridTest {
     public void removeAllColumns() {
         grid.removeAllColumns();
 
-        Assert.assertEquals(Collections.emptyList(), grid.getColumns());
+        assertEquals(Collections.emptyList(), grid.getColumns());
     }
 
     @Test
     public void removeAllColumnsInGridWithoutColumns() {
         grid.removeAllColumns();
         grid.removeAllColumns();
-        Assert.assertEquals(Collections.emptyList(), grid.getColumns());
+        assertEquals(Collections.emptyList(), grid.getColumns());
     }
 
     @Test
@@ -474,9 +468,9 @@ public class GridTest {
 
         List<Column<String, ?>> columns = grid.getColumns();
 
-        Assert.assertEquals(2, columns.size());
-        Assert.assertEquals("length", columns.get(0).getId());
-        Assert.assertEquals("foo", columns.get(1).getId());
+        assertEquals(2, columns.size());
+        assertEquals("length", columns.get(0).getId());
+        assertEquals("foo", columns.get(1).getId());
     }
 
     @Test(expected = IllegalStateException.class)
@@ -496,16 +490,16 @@ public class GridTest {
         grid.setColumns("born", "name");
 
         List<Column<Person, ?>> columns = grid.getColumns();
-        Assert.assertEquals(2, columns.size());
-        Assert.assertEquals("born", columns.get(0).getId());
-        Assert.assertEquals("name", columns.get(1).getId());
+        assertEquals(2, columns.size());
+        assertEquals("born", columns.get(0).getId());
+        assertEquals("name", columns.get(1).getId());
     }
 
     @Test
     public void setColumnOrder_byColumn() {
         grid.setColumnOrder(randomColumn, lengthColumn);
 
-        Assert.assertEquals(Arrays.asList(randomColumn, lengthColumn, fooColumn,
+        assertEquals(Arrays.asList(randomColumn, lengthColumn, fooColumn,
                 objectColumn), grid.getColumns());
     }
 
@@ -519,7 +513,7 @@ public class GridTest {
     public void setColumnOrder_byString() {
         grid.setColumnOrder("randomColumnId", "length");
 
-        Assert.assertEquals(Arrays.asList(randomColumn, lengthColumn, fooColumn,
+        assertEquals(Arrays.asList(randomColumn, lengthColumn, fooColumn,
                 objectColumn), grid.getColumns());
     }
 
@@ -563,12 +557,12 @@ public class GridTest {
                 .addColumn(ValueProvider.identity())
                 .getComparator(SortDirection.ASCENDING);
 
-        Assert.assertNotNull(comparator);
+        assertNotNull(comparator);
 
         List<Object> values = new ArrayList<>(Arrays.asList(expectedOrder));
         Collections.shuffle(values, new Random(42));
 
-        Assert.assertArrayEquals(expectedOrder,
+        assertArrayEquals(expectedOrder,
                 values.stream().sorted(comparator).toArray());
     }
 
@@ -587,7 +581,7 @@ public class GridTest {
         String formattedValue = Stream.of(rowData.keys())
                 .map(rowData::getString).filter(value -> !value.equals("Name"))
                 .findFirst().orElse(null);
-        Assert.assertEquals(formattedValue, "2,017");
+        assertEquals(formattedValue, "2,017");
     }
 
     @Test(expected = IllegalArgumentException.class)
@@ -605,7 +599,7 @@ public class GridTest {
 
     @Test
     public void columnId_sortProperty_noId() {
-        Assert.assertEquals(0,
+        assertEquals(0,
                 objectColumn.getSortOrder(SortDirection.ASCENDING).count());
     }
 
@@ -623,10 +617,9 @@ public class GridTest {
                 .getSortOrder(SortDirection.ASCENDING)
                 .toArray(QuerySortOrder[]::new);
 
-        Assert.assertEquals(1, sortOrders.length);
-        Assert.assertEquals(SortDirection.ASCENDING,
-                sortOrders[0].getDirection());
-        Assert.assertEquals(expectedProperty, sortOrders[0].getSorted());
+        assertEquals(1, sortOrders.length);
+        assertEquals(SortDirection.ASCENDING, sortOrders[0].getDirection());
+        assertEquals(expectedProperty, sortOrders[0].getSorted());
     }
 
     private static <T> JsonObject getRowData(Grid<T> grid, T row) {
diff --git a/server/src/test/java/com/vaadin/tests/server/component/gridlayout/DefaultAlignmentTest.java b/server/src/test/java/com/vaadin/tests/server/component/gridlayout/DefaultAlignmentTest.java
index 9b6368474f..c682a43674 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/gridlayout/DefaultAlignmentTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/gridlayout/DefaultAlignmentTest.java
@@ -1,6 +1,7 @@
 package com.vaadin.tests.server.component.gridlayout;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+
 import org.junit.Before;
 import org.junit.Test;
 
@@ -24,10 +25,9 @@ public class DefaultAlignmentTest {
         TextField tf = new TextField("A TextField");
         gridLayout.addComponent(label);
         gridLayout.addComponent(tf);
-        Assert.assertEquals(Alignment.TOP_LEFT,
+        assertEquals(Alignment.TOP_LEFT,
                 gridLayout.getComponentAlignment(label));
-        Assert.assertEquals(Alignment.TOP_LEFT,
-                gridLayout.getComponentAlignment(tf));
+        assertEquals(Alignment.TOP_LEFT, gridLayout.getComponentAlignment(tf));
     }
 
     @Test
@@ -37,9 +37,9 @@ public class DefaultAlignmentTest {
         gridLayout.setDefaultComponentAlignment(Alignment.MIDDLE_CENTER);
         gridLayout.addComponent(label);
         gridLayout.addComponent(tf);
-        Assert.assertEquals(Alignment.MIDDLE_CENTER,
+        assertEquals(Alignment.MIDDLE_CENTER,
                 gridLayout.getComponentAlignment(label));
-        Assert.assertEquals(Alignment.MIDDLE_CENTER,
+        assertEquals(Alignment.MIDDLE_CENTER,
                 gridLayout.getComponentAlignment(tf));
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/server/component/gridlayout/GridLayoutDeclarativeTest.java b/server/src/test/java/com/vaadin/tests/server/component/gridlayout/GridLayoutDeclarativeTest.java
index 0ca92e4ed5..a63ec8b20a 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/gridlayout/GridLayoutDeclarativeTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/gridlayout/GridLayoutDeclarativeTest.java
@@ -239,7 +239,7 @@ public class GridLayoutDeclarativeTest
                     continue;
                 }
 
-                Assert.assertEquals(expected.getComponentAlignment(eC),
+                assertEquals(expected.getComponentAlignment(eC),
                         result.getComponentAlignment(rC));
 
             }
@@ -297,7 +297,7 @@ public class GridLayoutDeclarativeTest
         Component component = Design.read(input);
         GridLayout readLayout = (GridLayout) component;
 
-        Assert.assertEquals(layout.getRows(), readLayout.getRows());
+        assertEquals(layout.getRows(), readLayout.getRows());
     }
 
     @Test
@@ -333,15 +333,15 @@ public class GridLayoutDeclarativeTest
                 + "</vaadin-grid-layout>";
         DesignContext context = Design
                 .read(new ByteArrayInputStream(design.getBytes(UTF_8)), null);
-        Assert.assertEquals(null, context.getCustomAttributes(
+        assertEquals(null, context.getCustomAttributes(
                 context.getComponentByLocalId("marginComponent")));
-        Assert.assertEquals(null, context.getCustomAttributes(
+        assertEquals(null, context.getCustomAttributes(
                 context.getComponentByLocalId("marginLeftComponent")));
-        Assert.assertEquals(null, context.getCustomAttributes(
+        assertEquals(null, context.getCustomAttributes(
                 context.getComponentByLocalId("marginRightComponent")));
-        Assert.assertEquals(null, context.getCustomAttributes(
+        assertEquals(null, context.getCustomAttributes(
                 context.getComponentByLocalId("marginTopComponent")));
-        Assert.assertEquals(null, context.getCustomAttributes(
+        assertEquals(null, context.getCustomAttributes(
                 context.getComponentByLocalId("marginBottomComponent")));
     }
 
@@ -355,8 +355,8 @@ public class GridLayoutDeclarativeTest
 
         PreconfiguredGridLayout myLayout = (PreconfiguredGridLayout) Design
                 .read(new ByteArrayInputStream(design.getBytes(UTF_8)));
-        Assert.assertEquals(2, myLayout.getRows());
-        Assert.assertEquals(2, myLayout.getColumns());
+        assertEquals(2, myLayout.getRows());
+        assertEquals(2, myLayout.getColumns());
     }
 
 }
diff --git a/server/src/test/java/com/vaadin/tests/server/component/label/LabelDeclarativeTest.java b/server/src/test/java/com/vaadin/tests/server/component/label/LabelDeclarativeTest.java
index 7a0a8957b0..d6eeb13d84 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/label/LabelDeclarativeTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/label/LabelDeclarativeTest.java
@@ -94,23 +94,23 @@ public class LabelDeclarativeTest extends DeclarativeTestBase<Label> {
     public void testHtmlEntities() {
         String design = "<vaadin-label plain-text=\"true\">&gt; Test</vaadin-label>";
         Label read = read(design);
-        Assert.assertEquals("> Test", read.getValue());
+        assertEquals("> Test", read.getValue());
 
         design = design.replace("plain-text=\"true\"", "");
         read = read(design);
-        Assert.assertEquals("&gt; Test", read.getValue());
+        assertEquals("&gt; Test", read.getValue());
 
         Label label = new Label("&amp; Test");
         label.setContentMode(ContentMode.TEXT);
 
         Element root = new Element(Tag.valueOf("vaadin-label"), "");
         label.writeDesign(root, new DesignContext());
-        Assert.assertEquals("&amp;amp; Test", root.html());
+        assertEquals("&amp;amp; Test", root.html());
 
         label.setContentMode(ContentMode.HTML);
         root = new Element(Tag.valueOf("vaadin-label"), "");
         label.writeDesign(root, new DesignContext());
-        Assert.assertEquals("&amp; Test", root.html());
+        assertEquals("&amp; Test", root.html());
     }
 
     /**
diff --git a/server/src/test/java/com/vaadin/tests/server/component/loginform/LoginFormTest.java b/server/src/test/java/com/vaadin/tests/server/component/loginform/LoginFormTest.java
index a69c3f32a2..b37eea5188 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/loginform/LoginFormTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/loginform/LoginFormTest.java
@@ -1,8 +1,9 @@
 package com.vaadin.tests.server.component.loginform;
 
+import static org.junit.Assert.assertEquals;
+
 import java.util.Iterator;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -27,9 +28,9 @@ public class LoginFormTest {
 
     @Test
     public void defaultCaptions() {
-        Assert.assertEquals("Username", loginForm.getUsernameCaption());
-        Assert.assertEquals("Password", loginForm.getPasswordCaption());
-        Assert.assertEquals("Login", loginForm.getLoginButtonCaption());
+        assertEquals("Username", loginForm.getUsernameCaption());
+        assertEquals("Password", loginForm.getPasswordCaption());
+        assertEquals("Login", loginForm.getLoginButtonCaption());
     }
 
     @Test
@@ -38,9 +39,9 @@ public class LoginFormTest {
         loginForm.setPasswordCaption("p");
         loginForm.setLoginButtonCaption("l");
 
-        Assert.assertEquals("u", loginForm.getUsernameCaption());
-        Assert.assertEquals("p", loginForm.getPasswordCaption());
-        Assert.assertEquals("l", loginForm.getLoginButtonCaption());
+        assertEquals("u", loginForm.getUsernameCaption());
+        assertEquals("p", loginForm.getPasswordCaption());
+        assertEquals("l", loginForm.getLoginButtonCaption());
     }
 
     @Test
@@ -51,9 +52,9 @@ public class LoginFormTest {
         loginForm.setPasswordCaption("p");
         loginForm.setLoginButtonCaption("l");
 
-        Assert.assertEquals("u", loginForm.getUsernameCaption());
-        Assert.assertEquals("p", loginForm.getPasswordCaption());
-        Assert.assertEquals("l", loginForm.getLoginButtonCaption());
+        assertEquals("u", loginForm.getUsernameCaption());
+        assertEquals("p", loginForm.getPasswordCaption());
+        assertEquals("l", loginForm.getLoginButtonCaption());
     }
 
     @Test
@@ -68,9 +69,9 @@ public class LoginFormTest {
         loginForm.setPasswordCaption("p");
         loginForm.setLoginButtonCaption("l");
 
-        Assert.assertEquals("u", loginForm.getUsernameCaption());
-        Assert.assertEquals("p", loginForm.getPasswordCaption());
-        Assert.assertEquals("l", loginForm.getLoginButtonCaption());
+        assertEquals("u", loginForm.getUsernameCaption());
+        assertEquals("p", loginForm.getPasswordCaption());
+        assertEquals("l", loginForm.getLoginButtonCaption());
     }
 
     @Test
@@ -100,8 +101,8 @@ public class LoginFormTest {
         ui.setContent(customForm);
         Iterator<Component> i = ((HasComponents) customForm.iterator().next())
                 .iterator();
-        Assert.assertEquals("Username caption", i.next().getCaption());
-        Assert.assertEquals("Password caption", i.next().getCaption());
-        Assert.assertEquals("Do it", i.next().getCaption());
+        assertEquals("Username caption", i.next().getCaption());
+        assertEquals("Password caption", i.next().getCaption());
+        assertEquals("Do it", i.next().getCaption());
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/server/component/menubar/MenuBarIdsTest.java b/server/src/test/java/com/vaadin/tests/server/component/menubar/MenuBarIdsTest.java
index bd8c2dd443..d06e1d438e 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/menubar/MenuBarIdsTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/menubar/MenuBarIdsTest.java
@@ -1,9 +1,11 @@
 package com.vaadin.tests.server.component.menubar;
 
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+
 import java.util.HashSet;
 import java.util.Set;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -81,7 +83,7 @@ public class MenuBarIdsTest implements Command {
     private static void assertUniqueIds(Set<Object> ids, MenuItem item) {
         int id = item.getId();
         System.out.println("Item " + item.getText() + ", id: " + id);
-        Assert.assertFalse(ids.contains(id));
+        assertFalse(ids.contains(id));
         ids.add(id);
         if (item.getChildren() != null) {
             for (MenuItem subItem : item.getChildren()) {
@@ -92,8 +94,7 @@ public class MenuBarIdsTest implements Command {
 
     @Override
     public void menuSelected(MenuItem selectedItem) {
-        Assert.assertNull(
-                "lastSelectedItem was not cleared before selecting an item",
+        assertNull("lastSelectedItem was not cleared before selecting an item",
                 lastSelectedItem);
 
         lastSelectedItem = selectedItem;
diff --git a/server/src/test/java/com/vaadin/tests/server/component/orderedlayout/DefaultAlignmentTest.java b/server/src/test/java/com/vaadin/tests/server/component/orderedlayout/DefaultAlignmentTest.java
index 7560c21adb..f0d9e9832a 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/orderedlayout/DefaultAlignmentTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/orderedlayout/DefaultAlignmentTest.java
@@ -1,6 +1,7 @@
 package com.vaadin.tests.server.component.orderedlayout;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+
 import org.junit.Before;
 import org.junit.Test;
 
@@ -37,10 +38,8 @@ public class DefaultAlignmentTest {
         TextField tf = new TextField("A TextField");
         layout.addComponent(label);
         layout.addComponent(tf);
-        Assert.assertEquals(Alignment.TOP_LEFT,
-                layout.getComponentAlignment(label));
-        Assert.assertEquals(Alignment.TOP_LEFT,
-                layout.getComponentAlignment(tf));
+        assertEquals(Alignment.TOP_LEFT, layout.getComponentAlignment(label));
+        assertEquals(Alignment.TOP_LEFT, layout.getComponentAlignment(tf));
     }
 
     @Test
@@ -59,9 +58,8 @@ public class DefaultAlignmentTest {
         layout.setDefaultComponentAlignment(Alignment.MIDDLE_CENTER);
         layout.addComponent(label);
         layout.addComponent(tf);
-        Assert.assertEquals(Alignment.MIDDLE_CENTER,
+        assertEquals(Alignment.MIDDLE_CENTER,
                 layout.getComponentAlignment(label));
-        Assert.assertEquals(Alignment.MIDDLE_CENTER,
-                layout.getComponentAlignment(tf));
+        assertEquals(Alignment.MIDDLE_CENTER, layout.getComponentAlignment(tf));
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/server/component/tabsheet/TabSheetTest.java b/server/src/test/java/com/vaadin/tests/server/component/tabsheet/TabSheetTest.java
index 91cfe7712a..54fb58a9c3 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/tabsheet/TabSheetTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/tabsheet/TabSheetTest.java
@@ -1,15 +1,16 @@
 package com.vaadin.tests.server.component.tabsheet;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
 
 import java.util.Iterator;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.shared.ui.tabsheet.TabsheetServerRpc;
@@ -35,7 +36,7 @@ public class TabSheetTest {
         Iterator<Component> iter = tabSheet.getComponentIterator();
 
         assertEquals(c, iter.next());
-        Assert.assertFalse(iter.hasNext());
+        assertFalse(iter.hasNext());
         assertNotNull(tabSheet.getTab(c));
     }
 
@@ -207,10 +208,10 @@ public class TabSheetTest {
         tabSheet.replaceComponent(lbl1, lbl2);
         assertSame(tab1, tabSheet.getTab(lbl1));
         assertSame(tab2, tabSheet.getTab(lbl2));
-        Assert.assertFalse(tab1.isClosable());
-        Assert.assertTrue(tab2.isClosable());
-        Assert.assertFalse(tab1.isEnabled());
-        Assert.assertTrue(tab2.isEnabled());
+        assertFalse(tab1.isClosable());
+        assertTrue(tab2.isClosable());
+        assertFalse(tab1.isEnabled());
+        assertTrue(tab2.isEnabled());
         assertEquals("description", tab1.getDescription());
         assertEquals(null, tab2.getDescription());
         assertEquals(3, tabSheet.getComponentCount());
@@ -226,7 +227,7 @@ public class TabSheetTest {
         assertNull(tabSheet.getTab(lbl1));
         assertNull(tab1.getComponent());
         assertNotNull(tabSheet.getTab(lbl3));
-        Assert.assertFalse(tabSheet.getTab(lbl3).isEnabled());
+        assertFalse(tabSheet.getTab(lbl3).isEnabled());
         assertEquals("description", tab1.getDescription());
         assertEquals(1, tabSheet.getTabPosition(tabSheet.getTab(lbl3)));
     }
@@ -322,18 +323,18 @@ public class TabSheetTest {
         });
 
         tabsheet.setSelectedTab(b2);
-        Assert.assertFalse(userOriginated.get());
-        Assert.assertEquals(b2, selected.get());
+        assertFalse(userOriginated.get());
+        assertEquals(b2, selected.get());
 
         TabsheetServerRpc rpc = ComponentTest.getRpcProxy(tabsheet,
                 TabsheetServerRpc.class);
         rpc.setSelected(tabsheet.getKey(b1));
-        Assert.assertTrue(userOriginated.get());
-        Assert.assertEquals(b1, selected.get());
+        assertTrue(userOriginated.get());
+        assertEquals(b1, selected.get());
 
         tabsheet.setSelectedTab(tabsheet.getTab(b4));
-        Assert.assertFalse(userOriginated.get());
-        Assert.assertEquals(b4, selected.get());
+        assertFalse(userOriginated.get());
+        assertEquals(b4, selected.get());
 
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/server/component/textarea/TextAreaDeclarativeTest.java b/server/src/test/java/com/vaadin/tests/server/component/textarea/TextAreaDeclarativeTest.java
index ad8d88e9c5..2c830279e9 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/textarea/TextAreaDeclarativeTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/textarea/TextAreaDeclarativeTest.java
@@ -68,7 +68,7 @@ public class TextAreaDeclarativeTest
     public void testHtmlEntities() throws IOException {
         String design = "<vaadin-text-area>&amp; Test</vaadin-text-area>";
         TextArea read = read(design);
-        Assert.assertEquals("& Test", read.getValue());
+        assertEquals("& Test", read.getValue());
 
         read.setValue("&amp; Test");
 
@@ -76,7 +76,7 @@ public class TextAreaDeclarativeTest
         Element root = new Element(Tag.valueOf("vaadin-text-area"), "");
         read.writeDesign(root, dc);
 
-        Assert.assertEquals("&amp;amp; Test", root.html());
+        assertEquals("&amp;amp; Test", root.html());
     }
 
     @Test
diff --git a/server/src/test/java/com/vaadin/tests/server/component/tree/TreeDeclarativeTest.java b/server/src/test/java/com/vaadin/tests/server/component/tree/TreeDeclarativeTest.java
index a8f7741f1b..b2c0c8ae21 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/tree/TreeDeclarativeTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/tree/TreeDeclarativeTest.java
@@ -1,6 +1,7 @@
 package com.vaadin.tests.server.component.tree;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertTrue;
+
 import org.junit.Test;
 
 import com.vaadin.data.TreeData;
@@ -32,28 +33,26 @@ public class TreeDeclarativeTest
         Tree<Person> tree = new Tree<>();
         tree.setTreeData(data);
         tree.setItemCaptionGenerator(item -> item.getFirstName());
-        
-        String designString = String.format("<%s>"
-                + "<node item='%s'>%s</node>"
-                + "<node item='%s' parent='%s'>%s</node>"
-                + "<node item='%s' parent='%s'>%s</node>"
-                + "<node item='%s' parent='%s'>%s</node>"
-                + "<node item='%s'>%s</node>"
-                + "</%s>", getComponentTag(),
-                person1.toString(), person1.getFirstName(),
+
+        String designString = String.format(
+                "<%s>" + "<node item='%s'>%s</node>"
+                        + "<node item='%s' parent='%s'>%s</node>"
+                        + "<node item='%s' parent='%s'>%s</node>"
+                        + "<node item='%s' parent='%s'>%s</node>"
+                        + "<node item='%s'>%s</node>" + "</%s>",
+                getComponentTag(), person1.toString(), person1.getFirstName(),
                 person2.toString(), person1.toString(), person2.getFirstName(),
                 person3.toString(), person1.toString(), person3.getFirstName(),
                 person4.toString(), person3.toString(), person4.getFirstName(),
-                person5.toString(), person5.getFirstName(),
-                getComponentTag());
+                person5.toString(), person5.getFirstName(), getComponentTag());
 
         testWrite(designString, tree, true);
         Tree<String> readTree = testRead(designString, tree);
-        Assert.assertEquals(2, readTree.getDataProvider()
+        assertEquals(2, readTree.getDataProvider()
                 .getChildCount(new HierarchicalQuery<>(null, null)));
-        Assert.assertEquals(2, readTree.getDataProvider().getChildCount(
+        assertEquals(2, readTree.getDataProvider().getChildCount(
                 new HierarchicalQuery<>(null, person1.toString())));
-        Assert.assertEquals(1, readTree.getDataProvider().getChildCount(
+        assertEquals(1, readTree.getDataProvider().getChildCount(
                 new HierarchicalQuery<>(null, person3.toString())));
     }
 
@@ -154,11 +153,11 @@ public class TreeDeclarativeTest
     @Override
     protected void assertEquals(String message, Object o1, Object o2) {
         if (o1 instanceof ItemCaptionGenerator) {
-            Assert.assertTrue(o2 instanceof ItemCaptionGenerator);
+            assertTrue(o2 instanceof ItemCaptionGenerator);
             return;
         }
         if (o1 instanceof IconGenerator) {
-            Assert.assertTrue(o2 instanceof IconGenerator);
+            assertTrue(o2 instanceof IconGenerator);
             return;
         }
         super.assertEquals(message, o1, o2);
diff --git a/server/src/test/java/com/vaadin/tests/server/component/treegrid/TreeGridDeclarativeTest.java b/server/src/test/java/com/vaadin/tests/server/component/treegrid/TreeGridDeclarativeTest.java
index a13ba357ef..5905d8d767 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/treegrid/TreeGridDeclarativeTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/treegrid/TreeGridDeclarativeTest.java
@@ -68,13 +68,13 @@ public class TreeGridDeclarativeTest
                 person7.getLastName(), getComponentTag());
 
         TreeGrid<String> readGrid = testRead(design, grid);
-        Assert.assertEquals(3, readGrid.getDataProvider()
+        assertEquals(3, readGrid.getDataProvider()
                 .size(new HierarchicalQuery<>(null, null)));
-        Assert.assertEquals(2, readGrid.getDataProvider()
+        assertEquals(2, readGrid.getDataProvider()
                 .size(new HierarchicalQuery<>(null, person1.toString())));
-        Assert.assertEquals(1, readGrid.getDataProvider()
+        assertEquals(1, readGrid.getDataProvider()
                 .size(new HierarchicalQuery<>(null, person5.toString())));
-        Assert.assertEquals(1, readGrid.getDataProvider()
+        assertEquals(1, readGrid.getDataProvider()
                 .size(new HierarchicalQuery<>(null, person6.toString())));
         testWrite(design, grid, true);
     }
diff --git a/server/src/test/java/com/vaadin/tests/server/component/upload/UploadDeclarativeTest.java b/server/src/test/java/com/vaadin/tests/server/component/upload/UploadDeclarativeTest.java
index 22695f3918..d43491f00c 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/upload/UploadDeclarativeTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/upload/UploadDeclarativeTest.java
@@ -15,7 +15,9 @@
  */
 package com.vaadin.tests.server.component.upload;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import org.junit.Test;
 
 import com.vaadin.tests.design.DeclarativeTestBase;
@@ -62,12 +64,11 @@ public class UploadDeclarativeTest extends DeclarativeTestBase<Upload> {
 
     @Test
     public void testImmediateModeDefault() {
-        Assert.assertTrue(
-                testRead("<v-upload />", new Upload()).isImmediateMode());
+        assertTrue(testRead("<v-upload />", new Upload()).isImmediateMode());
 
         Upload upload = new Upload();
         upload.setImmediateMode(false);
-        Assert.assertFalse(testRead("<v-upload immediate-mode=false />", upload)
+        assertFalse(testRead("<v-upload immediate-mode=false />", upload)
                 .isImmediateMode());
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/server/component/upload/UploadTest.java b/server/src/test/java/com/vaadin/tests/server/component/upload/UploadTest.java
index a2364b132d..a453769c66 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/upload/UploadTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/upload/UploadTest.java
@@ -15,7 +15,10 @@
  */
 package com.vaadin.tests.server.component.upload;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import org.junit.Test;
 
 import com.vaadin.server.StreamVariable;
@@ -38,14 +41,14 @@ public class UploadTest {
             variable.streamingFailed(new TestStreamingErrorEvent());
         } catch (Exception e) {
         }
-        Assert.assertFalse(upload.isUploading());
+        assertFalse(upload.isUploading());
     }
 
     @Test
     public void setImmediateMode_defaultTrue() {
         Upload upload = new Upload();
 
-        Assert.assertTrue("Upload should be in immediate mode by default",
+        assertTrue("Upload should be in immediate mode by default",
                 upload.isImmediateMode());
     }
 
@@ -53,7 +56,7 @@ public class UploadTest {
     public void getState_uploadHasCustomState() {
         TestUpload upload = new TestUpload();
         UploadState state = upload.getState();
-        Assert.assertEquals("Unexpected state class", UploadState.class,
+        assertEquals("Unexpected state class", UploadState.class,
                 state.getClass());
     }
 
@@ -61,14 +64,14 @@ public class UploadTest {
     public void getPrimaryStyleName_uploadHasCustomPrimaryStyleName() {
         Upload upload = new Upload();
         UploadState state = new UploadState();
-        Assert.assertEquals("Unexpected primary style name",
-                state.primaryStyleName, upload.getPrimaryStyleName());
+        assertEquals("Unexpected primary style name", state.primaryStyleName,
+                upload.getPrimaryStyleName());
     }
 
     @Test
     public void uploadStateHasCustomPrimaryStyleName() {
         UploadState state = new UploadState();
-        Assert.assertEquals("Unexpected primary style name", "v-upload",
+        assertEquals("Unexpected primary style name", "v-upload",
                 state.primaryStyleName);
     }
 
diff --git a/server/src/test/java/com/vaadin/tests/server/component/window/AttachDetachWindowTest.java b/server/src/test/java/com/vaadin/tests/server/component/window/AttachDetachWindowTest.java
index 8416a216c1..cd7570e7b6 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/window/AttachDetachWindowTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/window/AttachDetachWindowTest.java
@@ -226,7 +226,7 @@ public class AttachDetachWindowTest {
             eventFired[0] = event.getAttachedComponent().equals(window);
         });
         ui.addWindow(window);
-        Assert.assertTrue("Attach event is not fired for added window",
+        assertTrue("Attach event is not fired for added window",
                 eventFired[0]);
     }
 
@@ -242,7 +242,7 @@ public class AttachDetachWindowTest {
         ui.addWindow(window);
         ui.removeWindow(window);
 
-        Assert.assertTrue("Detach event is not fired for removed window",
+        assertTrue("Detach event is not fired for removed window",
                 eventFired[0]);
     }
 
diff --git a/server/src/test/java/com/vaadin/tests/server/component/window/WindowDeclarativeTest.java b/server/src/test/java/com/vaadin/tests/server/component/window/WindowDeclarativeTest.java
index ab4ef3b40f..a832ce6341 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/window/WindowDeclarativeTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/window/WindowDeclarativeTest.java
@@ -15,7 +15,8 @@
  */
 package com.vaadin.tests.server.component.window;
 
-import org.junit.Assert;
+import static org.junit.Assert.fail;
+
 import org.junit.Test;
 
 import com.vaadin.event.ShortcutAction.KeyCode;
@@ -134,7 +135,7 @@ public class WindowDeclarativeTest extends DeclarativeTestBase<Window> {
     protected void assertInvalidPosition(String position) {
         try {
             read("<vaadin-window position='" + position + "'>");
-            Assert.fail("Invalid position '" + position + "' should throw");
+            fail("Invalid position '" + position + "' should throw");
         } catch (Exception e) {
             // expected
         }
diff --git a/server/src/test/java/com/vaadin/tests/server/component/window/WindowTest.java b/server/src/test/java/com/vaadin/tests/server/component/window/WindowTest.java
index d743c4f009..aedcfbc5f0 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/window/WindowTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/window/WindowTest.java
@@ -15,7 +15,8 @@
  */
 package com.vaadin.tests.server.component.window;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+
 import org.junit.Before;
 import org.junit.Test;
 
@@ -38,23 +39,23 @@ public class WindowTest {
         Button b2 = new Button("button 2");
         window.setAssistiveDescription(l1, b2);
 
-        Assert.assertEquals(2, window.getAssistiveDescription().length);
-        Assert.assertEquals(l1, window.getAssistiveDescription()[0]);
-        Assert.assertEquals(b2, window.getAssistiveDescription()[1]);
+        assertEquals(2, window.getAssistiveDescription().length);
+        assertEquals(l1, window.getAssistiveDescription()[0]);
+        assertEquals(b2, window.getAssistiveDescription()[1]);
 
         // Modifying return value must not change actual value
         window.getAssistiveDescription()[0] = null;
 
-        Assert.assertEquals(2, window.getAssistiveDescription().length);
-        Assert.assertEquals(l1, window.getAssistiveDescription()[0]);
-        Assert.assertEquals(b2, window.getAssistiveDescription()[1]);
+        assertEquals(2, window.getAssistiveDescription().length);
+        assertEquals(l1, window.getAssistiveDescription()[0]);
+        assertEquals(b2, window.getAssistiveDescription()[1]);
 
     }
 
     @Test
     public void testSetPosition() {
         window.setPosition(100, 200);
-        Assert.assertEquals(100, window.getPositionX());
-        Assert.assertEquals(200, window.getPositionY());
+        assertEquals(100, window.getPositionX());
+        assertEquals(200, window.getPositionY());
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/server/componentcontainer/AddRemoveComponentTest.java b/server/src/test/java/com/vaadin/tests/server/componentcontainer/AddRemoveComponentTest.java
index e5537992c0..89c95ffeb8 100644
--- a/server/src/test/java/com/vaadin/tests/server/componentcontainer/AddRemoveComponentTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/componentcontainer/AddRemoveComponentTest.java
@@ -1,11 +1,13 @@
 package com.vaadin.tests.server.componentcontainer;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Modifier;
 import java.util.List;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.tests.VaadinClasses;
@@ -23,7 +25,7 @@ public class AddRemoveComponentTest {
         List<Class<? extends ComponentContainer>> containerClasses = VaadinClasses
                 .getComponentContainersSupportingAddRemoveComponent();
 
-        Assert.assertTrue(containerClasses.size() > 0);
+        assertTrue(containerClasses.size() > 0);
 
         // No default constructor, special case
         containerClasses.remove(CustomLayout.class);
@@ -52,7 +54,7 @@ public class AddRemoveComponentTest {
         hl.addComponent(label);
 
         componentContainer.removeComponent(label);
-        Assert.assertEquals(
+        assertEquals(
                 "Parent no longer correct for " + componentContainer.getClass(),
                 hl, label.getParent());
     }
diff --git a/server/src/test/java/com/vaadin/tests/server/componentcontainer/FormLayoutTest.java b/server/src/test/java/com/vaadin/tests/server/componentcontainer/FormLayoutTest.java
index 53bb87717f..10dc79da5b 100644
--- a/server/src/test/java/com/vaadin/tests/server/componentcontainer/FormLayoutTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/componentcontainer/FormLayoutTest.java
@@ -1,5 +1,6 @@
 package com.vaadin.tests.server.componentcontainer;
 
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertSame;
 import static org.junit.Assert.fail;
@@ -7,7 +8,6 @@ import static org.junit.Assert.fail;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.shared.ui.orderedlayout.FormLayoutState;
@@ -43,8 +43,8 @@ public class FormLayoutTest extends AbstractIndexedLayoutTestBase {
         return getLayout().getComponentCount();
     }
 
-    Component[] children = { new Label("A"), new Label("B"),
-            new Label("C"), new Label("D") };
+    Component[] children = { new Label("A"), new Label("B"), new Label("C"),
+            new Label("D") };
 
     @Test
     public void testConstructorWithComponents() {
@@ -63,7 +63,7 @@ public class FormLayoutTest extends AbstractIndexedLayoutTestBase {
     public void getState_formLayoutHasCustomState() {
         TestFormLayout layout = new TestFormLayout();
         FormLayoutState state = layout.getState();
-        Assert.assertEquals("Unexpected state class", FormLayoutState.class,
+        assertEquals("Unexpected state class", FormLayoutState.class,
                 state.getClass());
     }
 
@@ -71,14 +71,14 @@ public class FormLayoutTest extends AbstractIndexedLayoutTestBase {
     public void getPrimaryStyleName_formLayoutHasCustomPrimaryStyleName() {
         FormLayout layout = new FormLayout();
         FormLayoutState state = new FormLayoutState();
-        Assert.assertEquals("Unexpected primary style name",
-                state.primaryStyleName, layout.getPrimaryStyleName());
+        assertEquals("Unexpected primary style name", state.primaryStyleName,
+                layout.getPrimaryStyleName());
     }
 
     @Test
     public void formLayoutStateHasCustomPrimaryStyleName() {
         FormLayoutState state = new FormLayoutState();
-        Assert.assertEquals("Unexpected primary style name", "v-formlayout",
+        assertEquals("Unexpected primary style name", "v-formlayout",
                 state.primaryStyleName);
     }
 
diff --git a/server/src/test/java/com/vaadin/tests/server/componentcontainer/HorizontalLayoutTest.java b/server/src/test/java/com/vaadin/tests/server/componentcontainer/HorizontalLayoutTest.java
index 12f235011e..ec5784e7c4 100644
--- a/server/src/test/java/com/vaadin/tests/server/componentcontainer/HorizontalLayoutTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/componentcontainer/HorizontalLayoutTest.java
@@ -1,6 +1,8 @@
 package com.vaadin.tests.server.componentcontainer;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertSame;
+
 import org.junit.Test;
 
 import com.vaadin.ui.Button;
@@ -46,30 +48,30 @@ public class HorizontalLayoutTest extends AbstractIndexedLayoutTestBase {
 
         layout.addComponentsAndExpand(b1, b2);
 
-        Assert.assertEquals(3, layout.getComponentCount());
+        assertEquals(3, layout.getComponentCount());
 
-        Assert.assertSame(b3, layout.getComponent(0));
-        Assert.assertSame(b1, layout.getComponent(1));
-        Assert.assertSame(b2, layout.getComponent(2));
+        assertSame(b3, layout.getComponent(0));
+        assertSame(b1, layout.getComponent(1));
+        assertSame(b2, layout.getComponent(2));
 
-        Assert.assertEquals(0, layout.getExpandRatio(b3), 0);
-        Assert.assertEquals(1, layout.getExpandRatio(b1), 0);
-        Assert.assertEquals(1, layout.getExpandRatio(b2), 0);
+        assertEquals(0, layout.getExpandRatio(b3), 0);
+        assertEquals(1, layout.getExpandRatio(b1), 0);
+        assertEquals(1, layout.getExpandRatio(b2), 0);
 
-        Assert.assertEquals(-1, b3.getWidth(), 0);
-        Assert.assertEquals(100, b1.getWidth(), 0);
-        Assert.assertEquals(100, b2.getWidth(), 0);
+        assertEquals(-1, b3.getWidth(), 0);
+        assertEquals(100, b1.getWidth(), 0);
+        assertEquals(100, b2.getWidth(), 0);
     }
 
     @Test
     public void addAndExpand_undefinedHeightUpdated() {
         HorizontalLayout layout = getLayout();
 
-        Assert.assertEquals(-1, layout.getWidth(), 0);
+        assertEquals(-1, layout.getWidth(), 0);
 
         layout.addComponentsAndExpand();
 
-        Assert.assertEquals(100, layout.getWidth(), 0);
+        assertEquals(100, layout.getWidth(), 0);
     }
 
     @Test
@@ -80,7 +82,7 @@ public class HorizontalLayoutTest extends AbstractIndexedLayoutTestBase {
 
         layout.addComponentsAndExpand();
 
-        Assert.assertEquals(150, layout.getWidth(), 0);
+        assertEquals(150, layout.getWidth(), 0);
     }
 
 }
diff --git a/server/src/test/java/com/vaadin/tests/server/componentcontainer/VerticalLayoutTest.java b/server/src/test/java/com/vaadin/tests/server/componentcontainer/VerticalLayoutTest.java
index 2bb5d3a433..037b97c5a1 100644
--- a/server/src/test/java/com/vaadin/tests/server/componentcontainer/VerticalLayoutTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/componentcontainer/VerticalLayoutTest.java
@@ -1,6 +1,8 @@
 package com.vaadin.tests.server.componentcontainer;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertSame;
+
 import org.junit.Test;
 
 import com.vaadin.ui.Button;
@@ -46,30 +48,30 @@ public class VerticalLayoutTest extends AbstractIndexedLayoutTestBase {
 
         layout.addComponentsAndExpand(b1, b2);
 
-        Assert.assertEquals(3, layout.getComponentCount());
+        assertEquals(3, layout.getComponentCount());
 
-        Assert.assertSame(b3, layout.getComponent(0));
-        Assert.assertSame(b1, layout.getComponent(1));
-        Assert.assertSame(b2, layout.getComponent(2));
+        assertSame(b3, layout.getComponent(0));
+        assertSame(b1, layout.getComponent(1));
+        assertSame(b2, layout.getComponent(2));
 
-        Assert.assertEquals(0, layout.getExpandRatio(b3), 0);
-        Assert.assertEquals(1, layout.getExpandRatio(b1), 0);
-        Assert.assertEquals(1, layout.getExpandRatio(b2), 0);
+        assertEquals(0, layout.getExpandRatio(b3), 0);
+        assertEquals(1, layout.getExpandRatio(b1), 0);
+        assertEquals(1, layout.getExpandRatio(b2), 0);
 
-        Assert.assertEquals(-1, b3.getHeight(), 0);
-        Assert.assertEquals(100, b1.getHeight(), 0);
-        Assert.assertEquals(100, b2.getHeight(), 0);
+        assertEquals(-1, b3.getHeight(), 0);
+        assertEquals(100, b1.getHeight(), 0);
+        assertEquals(100, b2.getHeight(), 0);
     }
 
     @Test
     public void addAndExpand_undefinedHeightUpdated() {
         VerticalLayout layout = getLayout();
 
-        Assert.assertEquals(-1, layout.getHeight(), 0);
+        assertEquals(-1, layout.getHeight(), 0);
 
         layout.addComponentsAndExpand();
 
-        Assert.assertEquals(100, layout.getHeight(), 0);
+        assertEquals(100, layout.getHeight(), 0);
     }
 
     @Test
@@ -80,7 +82,7 @@ public class VerticalLayoutTest extends AbstractIndexedLayoutTestBase {
 
         layout.addComponentsAndExpand();
 
-        Assert.assertEquals(150, layout.getHeight(), 0);
+        assertEquals(150, layout.getHeight(), 0);
     }
 
 }
diff --git a/server/src/test/java/com/vaadin/tests/server/navigator/NavigatorTest.java b/server/src/test/java/com/vaadin/tests/server/navigator/NavigatorTest.java
index 019c13698d..2a756da1cb 100644
--- a/server/src/test/java/com/vaadin/tests/server/navigator/NavigatorTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/navigator/NavigatorTest.java
@@ -17,9 +17,11 @@
 package com.vaadin.tests.server.navigator;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
 import java.util.LinkedList;
@@ -31,7 +33,6 @@ import java.util.concurrent.atomic.AtomicReference;
 import org.easymock.EasyMock;
 import org.easymock.IArgumentMatcher;
 import org.easymock.IMocksControl;
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.navigator.NavigationStateManager;
@@ -370,24 +371,23 @@ public class NavigatorTest {
 
         TestNavigatorWithFragments navigator = new TestNavigatorWithFragments(
                 ui);
-        Assert.assertTrue("Add URI fragment Page method has not been called",
+        assertTrue("Add URI fragment Page method has not been called",
                 page.addUriFragmentCalled());
-        Assert.assertFalse("Unexpected remove URI fragment Page method call",
+        assertFalse("Unexpected remove URI fragment Page method call",
                 page.removeUriFragmentCalled());
-        Assert.assertNotNull("Navigator is null in UI", ui.getNavigator());
+        assertNotNull("Navigator is null in UI", ui.getNavigator());
 
         navigator.destroy();
-        Assert.assertTrue(
+        assertTrue(
                 "Remove URI fragment Page method has not been called after destroy",
                 page.removeUriFragmentCalled());
-        Assert.assertNull("Navigator is not null in UI after destroy",
+        assertNull("Navigator is not null in UI after destroy",
                 ui.getNavigator());
 
         try {
             page.setUriFragment("foobar", true); // This should throw
-            Assert.fail(
-                    "Expected null pointer exception after call uriFragmentChanged "
-                            + "for destroyed navigator");
+            fail("Expected null pointer exception after call uriFragmentChanged "
+                    + "for destroyed navigator");
         } catch (NullPointerException e) {
             // All ok.
         }
@@ -399,25 +399,24 @@ public class NavigatorTest {
         UI ui = new TestPushStateUI(page);
 
         TestNavigator navigator = new TestNavigator(ui);
-        Assert.assertTrue("Add URI fragment Page method has not been called",
+        assertTrue("Add URI fragment Page method has not been called",
                 page.addPopstateCalled());
-        Assert.assertFalse("Unexpected remove URI fragment Page method call",
+        assertFalse("Unexpected remove URI fragment Page method call",
                 page.removePopstateCalled());
-        Assert.assertNotNull("Navigator is null in UI", ui.getNavigator());
+        assertNotNull("Navigator is null in UI", ui.getNavigator());
 
         navigator.destroy();
-        Assert.assertTrue(
+        assertTrue(
                 "Remove URI fragment Page method has not been called after destroy",
                 page.removePopstateCalled());
-        Assert.assertNull("Navigator is not null in UI after destroy",
+        assertNull("Navigator is not null in UI after destroy",
                 ui.getNavigator());
 
         try {
             page.updateLocation("http://server/path/info", true, true);
 
-            Assert.fail(
-                    "Expected null pointer exception after call uriFragmentChanged "
-                            + "for destroyed navigator");
+            fail("Expected null pointer exception after call uriFragmentChanged "
+                    + "for destroyed navigator");
         } catch (NullPointerException e) {
             // All ok.
         }
@@ -531,12 +530,12 @@ public class NavigatorTest {
         navigator.addProvider(provider);
 
         navigator.navigateTo("test2");
-        Assert.assertEquals("", view2.getParams());
-        Assert.assertEquals(null, view1.getParams());
+        assertEquals("", view2.getParams());
+        assertEquals(null, view1.getParams());
         navigator.navigateTo("");
-        Assert.assertEquals("", view1.getParams());
+        assertEquals("", view1.getParams());
         navigator.navigateTo("test1/params");
-        Assert.assertEquals("params", view1.getParams());
+        assertEquals("params", view1.getParams());
     }
 
     @Test
@@ -1005,11 +1004,11 @@ public class NavigatorTest {
 
         // First time navigation
         navigator.navigateTo(viewName);
-        Assert.assertEquals(1, count[0]);
+        assertEquals(1, count[0]);
 
         // Second time navigation to the same view
         navigator.navigateTo(viewName);
-        Assert.assertEquals(1, count[0]);
+        assertEquals(1, count[0]);
     }
 
     public static class ViewIsNotAComponent implements View {
@@ -1065,8 +1064,8 @@ public class NavigatorTest {
         navigator.addView("foo", ViewIsNotAComponent.class);
         navigator.navigateTo("foo");
 
-        Assert.assertEquals(HorizontalLayout.class, ui.getContent().getClass());
-        Assert.assertEquals("Hello",
+        assertEquals(HorizontalLayout.class, ui.getContent().getClass());
+        assertEquals("Hello",
                 ((Label) ((HorizontalLayout) ui.getContent()).getComponent(0))
                         .getValue());
     }
@@ -1074,14 +1073,14 @@ public class NavigatorTest {
     @Test
     public void parameterMap_noViewSeparator() {
         Navigator navigator = createNavigatorWithState("fooview");
-        Assert.assertTrue(navigator.getStateParameterMap().isEmpty());
-        Assert.assertTrue(navigator.getStateParameterMap("foo").isEmpty());
+        assertTrue(navigator.getStateParameterMap().isEmpty());
+        assertTrue(navigator.getStateParameterMap("foo").isEmpty());
     }
 
     @Test
     public void parameterMap_noParameters() {
         Navigator navigator = createNavigatorWithState("fooview/");
-        Assert.assertTrue(navigator.getStateParameterMap().isEmpty());
+        assertTrue(navigator.getStateParameterMap().isEmpty());
     }
 
     @Test
@@ -1119,12 +1118,12 @@ public class NavigatorTest {
     @SafeVarargs
     private final void assertMap(Map<String, String> map,
             Entry<String, String>... entries) {
-        Assert.assertEquals(entries.length, map.size());
+        assertEquals(entries.length, map.size());
         for (Entry<String, String> entry : entries) {
-            Assert.assertTrue(
+            assertTrue(
                     "Map should contain a key called '" + entry.getKey() + "'",
                     map.containsKey(entry.getKey()));
-            Assert.assertEquals(entry.getValue(), map.get(entry.getKey()));
+            assertEquals(entry.getValue(), map.get(entry.getKey()));
         }
 
     }
@@ -1179,8 +1178,8 @@ public class NavigatorTest {
 
         navigator.navigateTo("view1");
 
-        Assert.assertTrue(mapRef.get().isEmpty());
-        Assert.assertTrue(mapRefB.get().isEmpty());
+        assertTrue(mapRef.get().isEmpty());
+        assertTrue(mapRefB.get().isEmpty());
         navigator.navigateTo("view1/a&b=c&d");
 
         assertMap(mapRef.get(), entry("a", ""), entry("b", "c"),
@@ -1208,7 +1207,7 @@ public class NavigatorTest {
         navigator.addView("view2", view2);
         navigator.navigateTo("view1");
         navigator.navigateTo("view2");
-        Assert.assertEquals("view1", navigator.getState());
+        assertEquals("view1", navigator.getState());
     }
 
     @Test
@@ -1231,7 +1230,7 @@ public class NavigatorTest {
         navigator.addView("view2", view2);
         navigator.navigateTo("view1");
         navigator.navigateTo("view2");
-        Assert.assertEquals("view2", navigator.getState());
+        assertEquals("view2", navigator.getState());
 
     }
 
@@ -1256,9 +1255,9 @@ public class NavigatorTest {
         navigator.addView("view2", view2);
         navigator.navigateTo("view1");
         navigator.navigateTo("view2");
-        Assert.assertEquals("view1", navigator.getState());
+        assertEquals("view1", navigator.getState());
         eventRef.get().navigate();
-        Assert.assertEquals("view2", navigator.getState());
+        assertEquals("view2", navigator.getState());
 
     }
 
@@ -1287,9 +1286,9 @@ public class NavigatorTest {
         navigator.runAfterLeaveConfirmation(() -> {
             leaveCount.incrementAndGet();
         });
-        Assert.assertEquals(0, leaveCount.get());
+        assertEquals(0, leaveCount.get());
         eventRef.get().navigate();
-        Assert.assertEquals(1, leaveCount.get());
-        Assert.assertEquals("view1", navigator.getState());
+        assertEquals(1, leaveCount.get());
+        assertEquals("view1", navigator.getState());
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/server/navigator/UriFragmentManagerTest.java b/server/src/test/java/com/vaadin/tests/server/navigator/UriFragmentManagerTest.java
index 230f2f2a65..66742dd7a1 100644
--- a/server/src/test/java/com/vaadin/tests/server/navigator/UriFragmentManagerTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/navigator/UriFragmentManagerTest.java
@@ -16,9 +16,12 @@
 
 package com.vaadin.tests.server.navigator;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import org.easymock.EasyMock;
 import org.easymock.IMocksControl;
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.navigator.Navigator;
@@ -40,10 +43,9 @@ public class UriFragmentManagerTest {
         EasyMock.replay(page);
 
         // test manager using the mock
-        Assert.assertEquals("Incorrect fragment value", "", manager.getState());
+        assertEquals("Incorrect fragment value", "", manager.getState());
         manager.setState("test");
-        Assert.assertEquals("Incorrect fragment value", "test",
-                manager.getState());
+        assertEquals("Incorrect fragment value", "test", manager.getState());
     }
 
     @Test
@@ -71,10 +73,10 @@ public class UriFragmentManagerTest {
         UriFragmentManager manager = new UriFragmentManager(page);
         manager.setNavigator(EasyMock.createMock(Navigator.class));
 
-        Assert.assertTrue(
+        assertTrue(
                 "addUriFragmentChangedListener() method is not called for the Page",
                 page.addUriFragmentCalled());
-        Assert.assertFalse(
+        assertFalse(
                 "removeUriFragmentChangedListener() method is called for the Page",
                 page.removeUriFragmentCalled());
     }
@@ -87,7 +89,7 @@ public class UriFragmentManagerTest {
         manager.setNavigator(EasyMock.createMock(Navigator.class));
 
         manager.setNavigator(null);
-        Assert.assertTrue(
+        assertTrue(
                 "removeUriFragmentChangedListener() method is not called for the Page",
                 page.removeUriFragmentCalled());
     }
diff --git a/server/src/test/java/com/vaadin/tests/util/TestUtil.java b/server/src/test/java/com/vaadin/tests/util/TestUtil.java
index eb5bd5e525..e98d6c07ab 100644
--- a/server/src/test/java/com/vaadin/tests/util/TestUtil.java
+++ b/server/src/test/java/com/vaadin/tests/util/TestUtil.java
@@ -1,13 +1,14 @@
 package com.vaadin.tests.util;
 
-import java.util.Iterator;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
 
-import org.junit.Assert;
+import java.util.Iterator;
 
 public class TestUtil {
     public static void assertArrays(Object[] actualObjects,
             Object[] expectedObjects) {
-        Assert.assertEquals(
+        assertEquals(
                 "Actual contains a different number of values than was expected",
                 expectedObjects.length, actualObjects.length);
 
@@ -15,8 +16,7 @@ public class TestUtil {
             Object actual = actualObjects[i];
             Object expected = expectedObjects[i];
 
-            Assert.assertEquals("Item[" + i + "] does not match", expected,
-                    actual);
+            assertEquals("Item[" + i + "] does not match", expected, actual);
         }
 
     }
@@ -29,18 +29,15 @@ public class TestUtil {
         while (i1.hasNext()) {
             Object o1 = i1.next();
             if (!i2.hasNext()) {
-                Assert.fail(
-                        "The second iterable contains fewer items than the first. The object "
-                                + o1 + " has no match in the second iterable.");
+                fail("The second iterable contains fewer items than the first. The object "
+                        + o1 + " has no match in the second iterable.");
             }
             Object o2 = i2.next();
-            Assert.assertEquals(o1, o2);
+            assertEquals(o1, o2);
         }
         if (i2.hasNext()) {
-            Assert.fail(
-                    "The second iterable contains more items than the first. The object "
-                            + i2.next()
-                            + " has no match in the first iterable.");
+            fail("The second iterable contains more items than the first. The object "
+                    + i2.next() + " has no match in the first iterable.");
         }
     }
 
diff --git a/server/src/test/java/com/vaadin/ui/AbstractListingTest.java b/server/src/test/java/com/vaadin/ui/AbstractListingTest.java
index deafe8368e..86f6929d38 100644
--- a/server/src/test/java/com/vaadin/ui/AbstractListingTest.java
+++ b/server/src/test/java/com/vaadin/ui/AbstractListingTest.java
@@ -1,5 +1,9 @@
 package com.vaadin.ui;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertTrue;
+
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.LinkedList;
@@ -7,7 +11,6 @@ import java.util.List;
 import java.util.stream.Stream;
 
 import org.jsoup.nodes.Element;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -73,8 +76,7 @@ public class AbstractListingTest {
         }
     }
 
-    private static final String[] ITEM_ARRAY = { "Foo", "Bar",
-            "Baz" };
+    private static final String[] ITEM_ARRAY = { "Foo", "Bar", "Baz" };
 
     private TestListing listing;
     private List<String> items;
@@ -89,20 +91,20 @@ public class AbstractListingTest {
     public void testSetItemsWithCollection() {
         listing.setItems(items);
         List<String> list = new LinkedList<>(items);
-        listing.getDataProvider().fetch(new Query()).forEach(
-                str -> Assert.assertTrue("Unexpected item in data provider",
+        listing.getDataProvider().fetch(new Query())
+                .forEach(str -> assertTrue("Unexpected item in data provider",
                         list.remove(str)));
-        Assert.assertTrue("Not all items from list were in data provider",
+        assertTrue("Not all items from list were in data provider",
                 list.isEmpty());
     }
 
     @Test
     public void testSetItemsWithVarargs() {
         listing.setItems(ITEM_ARRAY);
-        listing.getDataProvider().fetch(new Query()).forEach(
-                str -> Assert.assertTrue("Unexpected item in data provider",
+        listing.getDataProvider().fetch(new Query())
+                .forEach(str -> assertTrue("Unexpected item in data provider",
                         items.remove(str)));
-        Assert.assertTrue("Not all items from list were in data provider",
+        assertTrue("Not all items from list were in data provider",
                 items.isEmpty());
     }
 
@@ -111,14 +113,14 @@ public class AbstractListingTest {
         ListDataProvider<String> dataProvider = DataProvider
                 .ofCollection(items);
         listing.setDataProvider(dataProvider);
-        Assert.assertEquals("setDataProvider did not set data provider",
-                dataProvider, listing.getDataProvider());
+        assertEquals("setDataProvider did not set data provider", dataProvider,
+                listing.getDataProvider());
         listing.setDataProvider(
                 DataProvider.fromCallbacks(
                         query -> Stream.of(ITEM_ARRAY).skip(query.getOffset())
                                 .limit(query.getLimit()),
                         query -> ITEM_ARRAY.length));
-        Assert.assertNotEquals("setDataProvider did not replace data provider",
+        assertNotEquals("setDataProvider did not replace data provider",
                 dataProvider, listing.getDataProvider());
     }
 
@@ -128,7 +130,7 @@ public class AbstractListingTest {
         generator.extend(listing);
         listing.setItems("Foo");
         listing.runDataGeneration();
-        Assert.assertEquals("Generator should have been called once", 1,
+        assertEquals("Generator should have been called once", 1,
                 generator.callCount);
     }
 
@@ -138,7 +140,7 @@ public class AbstractListingTest {
         listing.setItems("Foo");
         generator.extend(listing);
         listing.runDataGeneration();
-        Assert.assertEquals("Generator should have been called once", 1,
+        assertEquals("Generator should have been called once", 1,
                 generator.callCount);
     }
 
@@ -148,10 +150,10 @@ public class AbstractListingTest {
         CountGenerator generator = new CountGenerator();
         generator.extend(listing);
         listing.runDataGeneration();
-        Assert.assertEquals("Generator should have been called once", 1,
+        assertEquals("Generator should have been called once", 1,
                 generator.callCount);
         listing.runDataGeneration();
-        Assert.assertEquals("Generator should not have been called again", 1,
+        assertEquals("Generator should not have been called again", 1,
                 generator.callCount);
     }
 
@@ -162,7 +164,7 @@ public class AbstractListingTest {
         generator.extend(listing);
         generator.remove();
         listing.runDataGeneration();
-        Assert.assertEquals("Generator should not have been called", 0,
+        assertEquals("Generator should not have been called", 0,
                 generator.callCount);
     }
 
@@ -172,11 +174,11 @@ public class AbstractListingTest {
         CountGenerator generator = new CountGenerator();
         generator.extend(listing);
         listing.runDataGeneration();
-        Assert.assertEquals("Generator should have been called once", 1,
+        assertEquals("Generator should have been called once", 1,
                 generator.callCount);
         generator.refresh("Foo");
         listing.runDataGeneration();
-        Assert.assertEquals("Generator should have been called again", 2,
+        assertEquals("Generator should have been called again", 2,
                 generator.callCount);
     }
 }
diff --git a/server/src/test/java/com/vaadin/ui/AbstractMultiSelectTest.java b/server/src/test/java/com/vaadin/ui/AbstractMultiSelectTest.java
index 0dcef85579..6bbd314761 100644
--- a/server/src/test/java/com/vaadin/ui/AbstractMultiSelectTest.java
+++ b/server/src/test/java/com/vaadin/ui/AbstractMultiSelectTest.java
@@ -15,6 +15,12 @@
  */
 package com.vaadin.ui;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
+
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -29,7 +35,6 @@ import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 import org.junit.After;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -124,7 +129,7 @@ public class AbstractMultiSelectTest<S extends AbstractMultiSelect<String>> {
 
         registration = selectToTest.addSelectionListener(event -> {
             listenerCount.incrementAndGet();
-            Assert.assertFalse(event.isUserOriginated());
+            assertFalse(event.isUserOriginated());
         });
 
         selectToTest.select("1");
@@ -136,23 +141,23 @@ public class AbstractMultiSelectTest<S extends AbstractMultiSelect<String>> {
         selectToTest.select("2", "3", "4");
         selectToTest.deselect("1", "4");
 
-        Assert.assertEquals(6, listenerCount.get());
+        assertEquals(6, listenerCount.get());
 
         // select partly selected
         selectToTest.select("2", "3", "4");
-        Assert.assertEquals(7, listenerCount.get());
+        assertEquals(7, listenerCount.get());
 
         // select completely selected
         selectToTest.select("2", "3", "4");
-        Assert.assertEquals(7, listenerCount.get());
+        assertEquals(7, listenerCount.get());
 
         // deselect partly not selected
         selectToTest.select("1", "4");
-        Assert.assertEquals(8, listenerCount.get());
+        assertEquals(8, listenerCount.get());
 
         // deselect completely not selected
         selectToTest.select("1", "4");
-        Assert.assertEquals(8, listenerCount.get());
+        assertEquals(8, listenerCount.get());
         verifyValueChangeEvents();
     }
 
@@ -162,7 +167,7 @@ public class AbstractMultiSelectTest<S extends AbstractMultiSelect<String>> {
 
         registration = selectToTest.addSelectionListener(event -> {
             listenerCount.incrementAndGet();
-            Assert.assertTrue(event.isUserOriginated());
+            assertTrue(event.isUserOriginated());
         });
 
         rpcSelect("1");
@@ -177,58 +182,58 @@ public class AbstractMultiSelectTest<S extends AbstractMultiSelect<String>> {
         rpcDeselectItems("1", "3");
         assertSelectionOrder("6");
 
-        Assert.assertEquals(5, listenerCount.get());
+        assertEquals(5, listenerCount.get());
 
         // select partly selected
         rpcSelect("2", "3", "4");
-        Assert.assertEquals(6, listenerCount.get());
+        assertEquals(6, listenerCount.get());
         assertSelectionOrder("6", "2", "3", "4");
 
         // select completely selected
         rpcSelect("2", "3", "4");
-        Assert.assertEquals(6, listenerCount.get());
+        assertEquals(6, listenerCount.get());
         assertSelectionOrder("6", "2", "3", "4");
 
         // deselect partly not selected
         rpcDeselectItems("1", "4");
-        Assert.assertEquals(7, listenerCount.get());
+        assertEquals(7, listenerCount.get());
         assertSelectionOrder("6", "2", "3");
 
         // deselect completely not selected
         rpcDeselectItems("1", "4");
-        Assert.assertEquals(7, listenerCount.get());
+        assertEquals(7, listenerCount.get());
         assertSelectionOrder("6", "2", "3");
 
         // select completely selected and deselect completely not selected
         rpcUpdateSelection(new String[] { "3" }, new String[] { "1", "4" });
-        Assert.assertEquals(7, listenerCount.get());
+        assertEquals(7, listenerCount.get());
         assertSelectionOrder("6", "2", "3");
 
         // select partly selected and deselect completely not selected
         rpcUpdateSelection(new String[] { "4", "2" },
                 new String[] { "1", "8" });
-        Assert.assertEquals(8, listenerCount.get());
+        assertEquals(8, listenerCount.get());
         assertSelectionOrder("6", "2", "3", "4");
 
         // select completely selected and deselect partly not selected
         rpcUpdateSelection(new String[] { "4", "3" },
                 new String[] { "1", "2" });
-        Assert.assertEquals(9, listenerCount.get());
+        assertEquals(9, listenerCount.get());
         assertSelectionOrder("6", "3", "4");
 
         // duplicate case - ignored
         rpcUpdateSelection(new String[] { "2" }, new String[] { "2" });
-        Assert.assertEquals(9, listenerCount.get());
+        assertEquals(9, listenerCount.get());
         assertSelectionOrder("6", "3", "4");
 
         // duplicate case - duplicate removed
         rpcUpdateSelection(new String[] { "2" }, new String[] { "2", "3" });
-        Assert.assertEquals(10, listenerCount.get());
+        assertEquals(10, listenerCount.get());
         assertSelectionOrder("6", "4");
 
         // duplicate case - duplicate removed
         rpcUpdateSelection(new String[] { "6", "8" }, new String[] { "6" });
-        Assert.assertEquals(11, listenerCount.get());
+        assertEquals(11, listenerCount.get());
         assertSelectionOrder("6", "4", "8");
         verifyValueChangeEvents();
     }
@@ -237,19 +242,18 @@ public class AbstractMultiSelectTest<S extends AbstractMultiSelect<String>> {
     public void getValue() {
         selectToTest.select("1");
 
-        Assert.assertEquals(Collections.singleton("1"),
-                selectToTest.getValue());
+        assertEquals(Collections.singleton("1"), selectToTest.getValue());
 
         selectToTest.deselectAll();
         LinkedHashSet<String> set = new LinkedHashSet<>();
         set.add("1");
         set.add("5");
         selectToTest.select(set.toArray(new String[2]));
-        Assert.assertEquals(set, selectToTest.getValue());
+        assertEquals(set, selectToTest.getValue());
 
         set.add("3");
         selectToTest.select("3");
-        Assert.assertEquals(set, selectToTest.getValue());
+        assertEquals(set, selectToTest.getValue());
         verifyValueChangeEvents();
     }
 
@@ -276,7 +280,7 @@ public class AbstractMultiSelectTest<S extends AbstractMultiSelect<String>> {
             }
         };
 
-        Assert.assertSame(set, select.getValue());
+        assertSame(set, select.getValue());
         verifyValueChangeEvents();
     }
 
@@ -284,7 +288,7 @@ public class AbstractMultiSelectTest<S extends AbstractMultiSelect<String>> {
     public void setValue() {
         selectToTest.setValue(Collections.singleton("1"));
 
-        Assert.assertEquals(Collections.singleton("1"),
+        assertEquals(Collections.singleton("1"),
                 selectToTest.getSelectedItems());
 
         Set<String> set = new LinkedHashSet<>();
@@ -292,7 +296,7 @@ public class AbstractMultiSelectTest<S extends AbstractMultiSelect<String>> {
         set.add("3");
         selectToTest.setValue(set);
 
-        Assert.assertEquals(set, selectToTest.getSelectedItems());
+        assertEquals(set, selectToTest.getSelectedItems());
         verifyValueChangeEvents();
     }
 
@@ -352,18 +356,18 @@ public class AbstractMultiSelectTest<S extends AbstractMultiSelect<String>> {
 
         AtomicReference<ValueChangeEvent<?>> event = new AtomicReference<>();
         Registration actualRegistration = select.addValueChangeListener(evt -> {
-            Assert.assertNull(event.get());
+            assertNull(event.get());
             event.set(evt);
         });
 
-        Assert.assertSame(registration, actualRegistration);
+        assertSame(registration, actualRegistration);
 
         selectionListener.get().selectionChange(new MultiSelectionEvent<>(
                 select, Mockito.mock(Set.class), true));
 
-        Assert.assertEquals(select, event.get().getComponent());
-        Assert.assertEquals(set, event.get().getValue());
-        Assert.assertTrue(event.get().isUserOriginated());
+        assertEquals(select, event.get().getComponent());
+        assertEquals(set, event.get().getValue());
+        assertTrue(event.get().isUserOriginated());
     }
 
     private void rpcSelect(String... keysToSelect) {
@@ -388,16 +392,16 @@ public class AbstractMultiSelectTest<S extends AbstractMultiSelect<String>> {
     }
 
     private void assertSelectionOrder(String... selectionOrder) {
-        Assert.assertEquals(Arrays.asList(selectionOrder),
+        assertEquals(Arrays.asList(selectionOrder),
                 new ArrayList<>(selectToTest.getSelectedItems()));
     }
 
     private void verifyValueChangeEvents() {
         if (oldValues.size() > 0) {
-            Assert.assertTrue(oldValues.get(0).isEmpty());
-            Assert.assertEquals(values.size(), oldValues.size());
+            assertTrue(oldValues.get(0).isEmpty());
+            assertEquals(values.size(), oldValues.size());
             for (int i = 0; i < oldValues.size() - 1; i++) {
-                Assert.assertEquals(values.get(i), oldValues.get(i + 1));
+                assertEquals(values.get(i), oldValues.get(i + 1));
             }
         }
     }
diff --git a/server/src/test/java/com/vaadin/ui/AbstractSingleSelectTest.java b/server/src/test/java/com/vaadin/ui/AbstractSingleSelectTest.java
index 5796f01cc5..d96793bf8e 100644
--- a/server/src/test/java/com/vaadin/ui/AbstractSingleSelectTest.java
+++ b/server/src/test/java/com/vaadin/ui/AbstractSingleSelectTest.java
@@ -17,6 +17,8 @@ package com.vaadin.ui;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertTrue;
 
 import java.util.ArrayList;
@@ -27,7 +29,6 @@ import java.util.Optional;
 import java.util.concurrent.atomic.AtomicReference;
 
 import org.jsoup.nodes.Element;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.Mockito;
@@ -190,10 +191,10 @@ public class AbstractSingleSelectTest {
     public void getValue() {
         listing.setSelectedItem(PERSON_B);
 
-        Assert.assertEquals(PERSON_B, listing.getValue());
+        assertEquals(PERSON_B, listing.getValue());
 
         listing.setValue(null);
-        Assert.assertNull(listing.getValue());
+        assertNull(listing.getValue());
         verifyValueChanges();
     }
 
@@ -205,22 +206,22 @@ public class AbstractSingleSelectTest {
         Mockito.when(select.getSelectedItem()).thenReturn(selected);
         Mockito.doCallRealMethod().when(select).getValue();
 
-        Assert.assertSame(selected.get(), select.getValue());
+        assertSame(selected.get(), select.getValue());
 
         selected = Optional.empty();
         Mockito.when(select.getSelectedItem()).thenReturn(selected);
-        Assert.assertNull(select.getValue());
+        assertNull(select.getValue());
     }
 
     @Test
     public void setValue() {
         listing.setValue(PERSON_C);
 
-        Assert.assertEquals(PERSON_C, listing.getSelectedItem().get());
+        assertEquals(PERSON_C, listing.getSelectedItem().get());
 
         listing.setValue(null);
 
-        Assert.assertFalse(listing.getSelectedItem().isPresent());
+        assertFalse(listing.getSelectedItem().isPresent());
         verifyValueChanges();
     }
 
@@ -281,18 +282,18 @@ public class AbstractSingleSelectTest {
 
         AtomicReference<ValueChangeEvent<?>> event = new AtomicReference<>();
         Registration actualRegistration = select.addValueChangeListener(evt -> {
-            Assert.assertNull(event.get());
+            assertNull(event.get());
             event.set(evt);
         });
-        Assert.assertSame(registration, actualRegistration);
+        assertSame(registration, actualRegistration);
 
         selectionListener.get().selectionChange(
                 new SingleSelectionEvent<>(select, value, true));
 
-        Assert.assertEquals(select, event.get().getComponent());
-        Assert.assertEquals(value, event.get().getOldValue());
-        Assert.assertEquals(value, event.get().getValue());
-        Assert.assertTrue(event.get().isUserOriginated());
+        assertEquals(select, event.get().getComponent());
+        assertEquals(value, event.get().getOldValue());
+        assertEquals(value, event.get().getValue());
+        assertTrue(event.get().isUserOriginated());
     }
 
     private void verifyValueChanges() {
diff --git a/server/src/test/java/com/vaadin/ui/CheckBoxTest.java b/server/src/test/java/com/vaadin/ui/CheckBoxTest.java
index 539d6fbf63..d2c280f12d 100644
--- a/server/src/test/java/com/vaadin/ui/CheckBoxTest.java
+++ b/server/src/test/java/com/vaadin/ui/CheckBoxTest.java
@@ -15,9 +15,11 @@
  */
 package com.vaadin.ui;
 
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import java.util.concurrent.atomic.AtomicBoolean;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.server.ServerRpcManager;
@@ -29,16 +31,16 @@ public class CheckBoxTest {
     @Test
     public void initiallyFalse() {
         CheckBox cb = new CheckBox();
-        Assert.assertFalse(cb.getValue());
+        assertFalse(cb.getValue());
     }
 
     @Test
     public void testSetValue() {
         CheckBox cb = new CheckBox();
         cb.setValue(true);
-        Assert.assertTrue(cb.getValue());
+        assertTrue(cb.getValue());
         cb.setValue(false);
-        Assert.assertFalse(cb.getValue());
+        assertFalse(cb.getValue());
     }
 
     @Test
@@ -53,12 +55,12 @@ public class CheckBoxTest {
         ComponentTest.syncToClient(cb);
         ServerRpcManager.getRpcProxy(cb, CheckBoxServerRpc.class)
                 .setChecked(true, new MouseEventDetails());
-        Assert.assertTrue(userOriginated.get());
+        assertTrue(userOriginated.get());
         userOriginated.set(false);
         ComponentTest.syncToClient(cb);
         ServerRpcManager.getRpcProxy(cb, CheckBoxServerRpc.class)
                 .setChecked(false, new MouseEventDetails());
-        Assert.assertTrue(userOriginated.get());
+        assertTrue(userOriginated.get());
     }
 
     @Test
@@ -71,10 +73,10 @@ public class CheckBoxTest {
             userOriginated.set(e.isUserOriginated());
         });
         cb.setValue(true);
-        Assert.assertFalse(userOriginated.get());
+        assertFalse(userOriginated.get());
         userOriginated.set(true);
         cb.setValue(false);
-        Assert.assertFalse(userOriginated.get());
+        assertFalse(userOriginated.get());
     }
 
     @Test(expected = NullPointerException.class)
diff --git a/server/src/test/java/com/vaadin/ui/ComponentTest.java b/server/src/test/java/com/vaadin/ui/ComponentTest.java
index 58a8829d5e..23e15e1bff 100644
--- a/server/src/test/java/com/vaadin/ui/ComponentTest.java
+++ b/server/src/test/java/com/vaadin/ui/ComponentTest.java
@@ -15,12 +15,12 @@
  */
 package com.vaadin.ui;
 
+import static org.junit.Assert.assertEquals;
+
 import java.lang.reflect.Method;
 import java.util.Arrays;
 import java.util.HashSet;
 
-import org.junit.Assert;
-
 import com.vaadin.server.ClientConnector;
 import com.vaadin.server.LegacyCommunicationManager;
 import com.vaadin.server.ServerRpcManager;
@@ -111,8 +111,7 @@ public class ComponentTest {
         JsonObject encodeState = connector.encodeState();
 
         // Collect to HashSet so that order doesn't matter
-        Assert.assertEquals(message,
-                new HashSet<>(Arrays.asList(expectedProperties)),
+        assertEquals(message, new HashSet<>(Arrays.asList(expectedProperties)),
                 new HashSet<>(Arrays.asList(encodeState.keys())));
     }
 
diff --git a/server/src/test/java/com/vaadin/ui/CustomFieldTest.java b/server/src/test/java/com/vaadin/ui/CustomFieldTest.java
index 94636dcdc0..e193809c1a 100644
--- a/server/src/test/java/com/vaadin/ui/CustomFieldTest.java
+++ b/server/src/test/java/com/vaadin/ui/CustomFieldTest.java
@@ -15,10 +15,14 @@
  */
 package com.vaadin.ui;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
 import java.util.Iterator;
 import java.util.NoSuchElementException;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 public class CustomFieldTest {
@@ -54,10 +58,10 @@ public class CustomFieldTest {
         // iterator() can't do it even though it should...
         field.getContent();
         Iterator<Component> iterator = field.iterator();
-        Assert.assertNotNull(iterator);
-        Assert.assertTrue(iterator.hasNext());
-        Assert.assertEquals(field.button, iterator.next());
-        Assert.assertFalse(iterator.hasNext());
+        assertNotNull(iterator);
+        assertTrue(iterator.hasNext());
+        assertEquals(field.button, iterator.next());
+        assertFalse(iterator.hasNext());
         iterator.next();
     }
 }
diff --git a/server/src/test/java/com/vaadin/ui/DateFieldConstructorTest.java b/server/src/test/java/com/vaadin/ui/DateFieldConstructorTest.java
index 6fa83f14d0..7bd7aeda24 100644
--- a/server/src/test/java/com/vaadin/ui/DateFieldConstructorTest.java
+++ b/server/src/test/java/com/vaadin/ui/DateFieldConstructorTest.java
@@ -15,34 +15,37 @@
  */
 package com.vaadin.ui;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+
 import java.time.LocalDate;
 
-import org.junit.Assert;
 import org.junit.Test;
 import org.mockito.Mockito;
 
 import com.vaadin.data.HasValue;
 import com.vaadin.shared.ui.datefield.DateResolution;
-import static org.mockito.Mockito.never;
-import static org.mockito.Mockito.verify;
 
 public class DateFieldConstructorTest {
 
     @Test
     public void initiallyEmpty() {
         DateField dateField = new DateField();
-        Assert.assertTrue(dateField.isEmpty());
-        Assert.assertEquals(DateResolution.DAY, dateField.getResolution());
+        assertTrue(dateField.isEmpty());
+        assertEquals(DateResolution.DAY, dateField.getResolution());
     }
 
     @Test
     public void testValueConstructor_emptyAfterClear() {
         DateField dateField = new DateField(null, LocalDate.now());
-        Assert.assertEquals(DateResolution.DAY, dateField.getResolution());
-        Assert.assertFalse(dateField.isEmpty());
+        assertEquals(DateResolution.DAY, dateField.getResolution());
+        assertFalse(dateField.isEmpty());
 
         dateField.clear();
-        Assert.assertTrue(dateField.isEmpty());
+        assertTrue(dateField.isEmpty());
     }
 
     @Test
@@ -50,7 +53,7 @@ public class DateFieldConstructorTest {
         HasValue.ValueChangeListener valueChangeListener = Mockito
                 .mock(HasValue.ValueChangeListener.class);
         DateField dateField = new DateField(valueChangeListener);
-        Assert.assertEquals(DateResolution.DAY, dateField.getResolution());
+        assertEquals(DateResolution.DAY, dateField.getResolution());
 
         dateField.setValue(LocalDate.now());
 
@@ -65,7 +68,7 @@ public class DateFieldConstructorTest {
                 .mock(HasValue.ValueChangeListener.class);
         DateField dateField = new DateField("Caption", LocalDate.now(),
                 valueChangeListener);
-        Assert.assertEquals(DateResolution.DAY, dateField.getResolution());
+        assertEquals(DateResolution.DAY, dateField.getResolution());
 
         verify(valueChangeListener, never())
                 .valueChange(Mockito.any(HasValue.ValueChangeEvent.class));
diff --git a/server/src/test/java/com/vaadin/ui/DateFieldTestCase.java b/server/src/test/java/com/vaadin/ui/DateFieldTestCase.java
index e67d7bde13..f50141df66 100644
--- a/server/src/test/java/com/vaadin/ui/DateFieldTestCase.java
+++ b/server/src/test/java/com/vaadin/ui/DateFieldTestCase.java
@@ -3,10 +3,11 @@ package com.vaadin.ui;
 import static org.hamcrest.CoreMatchers.is;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.core.IsNull.nullValue;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
 
 import java.time.LocalDate;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -33,14 +34,14 @@ public class DateFieldTestCase {
     public void rangeStartIsAcceptedAsValue() {
         dateField.setRangeStart(date);
         dateField.setValue(date);
-        Assert.assertNull(dateField.getComponentError());
+        assertNull(dateField.getComponentError());
     }
 
     @Test
     public void belowRangeStartIsNotAcceptedAsValue() {
         dateField.setRangeStart(date);
         dateField.setValue(date.minusDays(1));
-        Assert.assertNotNull(dateField.getComponentError());
+        assertNotNull(dateField.getComponentError());
     }
 
     @Test
@@ -54,13 +55,13 @@ public class DateFieldTestCase {
     public void rangeEndIsAcceptedAsValue() {
         dateField.setRangeEnd(date);
         dateField.setValue(date);
-        Assert.assertNull(dateField.getComponentError());
+        assertNull(dateField.getComponentError());
     }
 
     @Test
     public void aboveRangeEndIsNotAcceptedAsValue() {
         dateField.setRangeEnd(date);
         dateField.setValue(date.plusDays(1));
-        Assert.assertNotNull(dateField.getComponentError());
+        assertNotNull(dateField.getComponentError());
     }
 }
diff --git a/server/src/test/java/com/vaadin/ui/DateTimeFieldConstructorTest.java b/server/src/test/java/com/vaadin/ui/DateTimeFieldConstructorTest.java
index 90a452942e..d4675556c3 100644
--- a/server/src/test/java/com/vaadin/ui/DateTimeFieldConstructorTest.java
+++ b/server/src/test/java/com/vaadin/ui/DateTimeFieldConstructorTest.java
@@ -15,37 +15,38 @@
  */
 package com.vaadin.ui;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+
 import java.time.LocalDateTime;
 
-import org.junit.Assert;
 import org.junit.Test;
 import org.mockito.Mockito;
 
 import com.vaadin.data.HasValue;
 import com.vaadin.shared.ui.datefield.DateTimeResolution;
-import static org.mockito.Mockito.never;
-import static org.mockito.Mockito.verify;
 
 public class DateTimeFieldConstructorTest {
 
     @Test
     public void initiallyEmpty() {
         DateTimeField dateTimeField = new DateTimeField();
-        Assert.assertTrue(dateTimeField.isEmpty());
-        Assert.assertEquals(DateTimeResolution.MINUTE,
-                dateTimeField.getResolution());
+        assertTrue(dateTimeField.isEmpty());
+        assertEquals(DateTimeResolution.MINUTE, dateTimeField.getResolution());
     }
 
     @Test
     public void testValueConstructor_emptyAfterClear() {
         DateTimeField dateTimeField = new DateTimeField(null,
                 LocalDateTime.now());
-        Assert.assertFalse(dateTimeField.isEmpty());
-        Assert.assertEquals(DateTimeResolution.MINUTE,
-                dateTimeField.getResolution());
+        assertFalse(dateTimeField.isEmpty());
+        assertEquals(DateTimeResolution.MINUTE, dateTimeField.getResolution());
 
         dateTimeField.clear();
-        Assert.assertTrue(dateTimeField.isEmpty());
+        assertTrue(dateTimeField.isEmpty());
     }
 
     @Test
@@ -53,8 +54,7 @@ public class DateTimeFieldConstructorTest {
         HasValue.ValueChangeListener valueChangeListener = Mockito
                 .mock(HasValue.ValueChangeListener.class);
         DateTimeField dateTimeField = new DateTimeField(valueChangeListener);
-        Assert.assertEquals(DateTimeResolution.MINUTE,
-                dateTimeField.getResolution());
+        assertEquals(DateTimeResolution.MINUTE, dateTimeField.getResolution());
 
         dateTimeField.setValue(LocalDateTime.now());
 
@@ -69,8 +69,7 @@ public class DateTimeFieldConstructorTest {
                 .mock(HasValue.ValueChangeListener.class);
         DateTimeField dateTimeField = new DateTimeField("Caption",
                 LocalDateTime.now(), valueChangeListener);
-        Assert.assertEquals(DateTimeResolution.MINUTE,
-                dateTimeField.getResolution());
+        assertEquals(DateTimeResolution.MINUTE, dateTimeField.getResolution());
 
         verify(valueChangeListener, never())
                 .valueChange(Mockito.any(HasValue.ValueChangeEvent.class));
diff --git a/server/src/test/java/com/vaadin/ui/HorizontalSplitPanelTest.java b/server/src/test/java/com/vaadin/ui/HorizontalSplitPanelTest.java
index fcdb0a85ad..2eb3ba5f3c 100644
--- a/server/src/test/java/com/vaadin/ui/HorizontalSplitPanelTest.java
+++ b/server/src/test/java/com/vaadin/ui/HorizontalSplitPanelTest.java
@@ -15,7 +15,8 @@
  */
 package com.vaadin.ui;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+
 import org.junit.Test;
 
 import com.vaadin.shared.ui.splitpanel.HorizontalSplitPanelState;
@@ -24,7 +25,7 @@ public class HorizontalSplitPanelTest {
 
     @Test
     public void primaryStyleName() {
-        Assert.assertEquals(new HorizontalSplitPanelState().primaryStyleName,
+        assertEquals(new HorizontalSplitPanelState().primaryStyleName,
                 new HorizontalSplitPanel().getPrimaryStyleName());
     }
 }
diff --git a/server/src/test/java/com/vaadin/ui/InlineDateFieldConstructorTest.java b/server/src/test/java/com/vaadin/ui/InlineDateFieldConstructorTest.java
index 936efcdc03..1bf518460f 100644
--- a/server/src/test/java/com/vaadin/ui/InlineDateFieldConstructorTest.java
+++ b/server/src/test/java/com/vaadin/ui/InlineDateFieldConstructorTest.java
@@ -15,35 +15,37 @@
  */
 package com.vaadin.ui;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+
 import java.time.LocalDate;
 
-import org.junit.Assert;
 import org.junit.Test;
 import org.mockito.Mockito;
 
 import com.vaadin.data.HasValue;
 import com.vaadin.shared.ui.datefield.DateResolution;
 
-import static org.mockito.Mockito.never;
-import static org.mockito.Mockito.verify;
-
 public class InlineDateFieldConstructorTest {
 
     @Test
     public void initiallyEmpty() {
         InlineDateField dateField = new InlineDateField();
-        Assert.assertTrue(dateField.isEmpty());
-        Assert.assertEquals(DateResolution.DAY, dateField.getResolution());
+        assertTrue(dateField.isEmpty());
+        assertEquals(DateResolution.DAY, dateField.getResolution());
     }
 
     @Test
     public void testValueConstructor_emptyAfterClear() {
         InlineDateField dateField = new InlineDateField(null, LocalDate.now());
-        Assert.assertEquals(DateResolution.DAY, dateField.getResolution());
-        Assert.assertFalse(dateField.isEmpty());
+        assertEquals(DateResolution.DAY, dateField.getResolution());
+        assertFalse(dateField.isEmpty());
 
         dateField.clear();
-        Assert.assertTrue(dateField.isEmpty());
+        assertTrue(dateField.isEmpty());
     }
 
     @Test
@@ -51,7 +53,7 @@ public class InlineDateFieldConstructorTest {
         HasValue.ValueChangeListener valueChangeListener = Mockito
                 .mock(HasValue.ValueChangeListener.class);
         InlineDateField dateField = new InlineDateField(valueChangeListener);
-        Assert.assertEquals(DateResolution.DAY, dateField.getResolution());
+        assertEquals(DateResolution.DAY, dateField.getResolution());
 
         dateField.setValue(LocalDate.now());
 
@@ -66,7 +68,7 @@ public class InlineDateFieldConstructorTest {
                 .mock(HasValue.ValueChangeListener.class);
         InlineDateField dateField = new InlineDateField("Caption",
                 LocalDate.now(), valueChangeListener);
-        Assert.assertEquals(DateResolution.DAY, dateField.getResolution());
+        assertEquals(DateResolution.DAY, dateField.getResolution());
 
         verify(valueChangeListener, never())
                 .valueChange(Mockito.any(HasValue.ValueChangeEvent.class));
diff --git a/server/src/test/java/com/vaadin/ui/InlineDateTimeFieldConstructorTest.java b/server/src/test/java/com/vaadin/ui/InlineDateTimeFieldConstructorTest.java
index 6a2aaca7aa..0c900276b6 100644
--- a/server/src/test/java/com/vaadin/ui/InlineDateTimeFieldConstructorTest.java
+++ b/server/src/test/java/com/vaadin/ui/InlineDateTimeFieldConstructorTest.java
@@ -15,38 +15,38 @@
  */
 package com.vaadin.ui;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+
 import java.time.LocalDateTime;
 
-import org.junit.Assert;
 import org.junit.Test;
 import org.mockito.Mockito;
 
 import com.vaadin.data.HasValue;
 import com.vaadin.shared.ui.datefield.DateTimeResolution;
 
-import static org.mockito.Mockito.never;
-import static org.mockito.Mockito.verify;
-
 public class InlineDateTimeFieldConstructorTest {
 
     @Test
     public void initiallyEmpty() {
         InlineDateTimeField dateTimeField = new InlineDateTimeField();
-        Assert.assertTrue(dateTimeField.isEmpty());
-        Assert.assertEquals(DateTimeResolution.MINUTE,
-                dateTimeField.getResolution());
+        assertTrue(dateTimeField.isEmpty());
+        assertEquals(DateTimeResolution.MINUTE, dateTimeField.getResolution());
     }
 
     @Test
     public void testValueConstructor_emptyAfterClear() {
         InlineDateTimeField dateTimeField = new InlineDateTimeField(null,
                 LocalDateTime.now());
-        Assert.assertFalse(dateTimeField.isEmpty());
-        Assert.assertEquals(DateTimeResolution.MINUTE,
-                dateTimeField.getResolution());
+        assertFalse(dateTimeField.isEmpty());
+        assertEquals(DateTimeResolution.MINUTE, dateTimeField.getResolution());
 
         dateTimeField.clear();
-        Assert.assertTrue(dateTimeField.isEmpty());
+        assertTrue(dateTimeField.isEmpty());
     }
 
     @Test
@@ -55,8 +55,7 @@ public class InlineDateTimeFieldConstructorTest {
                 .mock(HasValue.ValueChangeListener.class);
         InlineDateTimeField dateTimeField = new InlineDateTimeField(
                 valueChangeListener);
-        Assert.assertEquals(DateTimeResolution.MINUTE,
-                dateTimeField.getResolution());
+        assertEquals(DateTimeResolution.MINUTE, dateTimeField.getResolution());
 
         dateTimeField.setValue(LocalDateTime.now());
 
@@ -71,8 +70,7 @@ public class InlineDateTimeFieldConstructorTest {
                 .mock(HasValue.ValueChangeListener.class);
         InlineDateTimeField dateTimeField = new InlineDateTimeField("Caption",
                 LocalDateTime.now(), valueChangeListener);
-        Assert.assertEquals(DateTimeResolution.MINUTE,
-                dateTimeField.getResolution());
+        assertEquals(DateTimeResolution.MINUTE, dateTimeField.getResolution());
 
         verify(valueChangeListener, never())
                 .valueChange(Mockito.any(HasValue.ValueChangeEvent.class));
diff --git a/server/src/test/java/com/vaadin/ui/LabelTest.java b/server/src/test/java/com/vaadin/ui/LabelTest.java
index 5bf082f659..e98c4a0d7b 100644
--- a/server/src/test/java/com/vaadin/ui/LabelTest.java
+++ b/server/src/test/java/com/vaadin/ui/LabelTest.java
@@ -1,25 +1,26 @@
 package com.vaadin.ui;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+
 import org.junit.Test;
 
 public class LabelTest {
 
     @Test
     public void emptyLabelValue() {
-        Assert.assertEquals("", new Label().getValue());
+        assertEquals("", new Label().getValue());
     }
 
     @Test
     public void labelInitialValue() {
-        Assert.assertEquals("initial", new Label("initial").getValue());
+        assertEquals("initial", new Label("initial").getValue());
     }
 
     @Test
     public void labelSetValue() {
         Label label = new Label();
         label.setValue("foo");
-        Assert.assertEquals("foo", label.getValue());
+        assertEquals("foo", label.getValue());
     }
 
 }
diff --git a/server/src/test/java/com/vaadin/ui/PasswordFieldConstructorTest.java b/server/src/test/java/com/vaadin/ui/PasswordFieldConstructorTest.java
index d6f8cc2a5c..a9ad4bbbe5 100644
--- a/server/src/test/java/com/vaadin/ui/PasswordFieldConstructorTest.java
+++ b/server/src/test/java/com/vaadin/ui/PasswordFieldConstructorTest.java
@@ -15,29 +15,31 @@
  */
 package com.vaadin.ui;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+
 import org.junit.Test;
 import org.mockito.Mockito;
 
 import com.vaadin.data.HasValue;
-import static org.mockito.Mockito.never;
-import static org.mockito.Mockito.verify;
 
 public class PasswordFieldConstructorTest {
 
     @Test
     public void initiallyEmpty() {
         PasswordField passwordField = new PasswordField();
-        Assert.assertTrue(passwordField.isEmpty());
+        assertTrue(passwordField.isEmpty());
     }
 
     @Test
     public void testValueConstructor_emptyAfterClear() {
         PasswordField passwordField = new PasswordField(null, "foobar");
-        Assert.assertFalse(passwordField.isEmpty());
+        assertFalse(passwordField.isEmpty());
 
         passwordField.clear();
-        Assert.assertTrue(passwordField.isEmpty());
+        assertTrue(passwordField.isEmpty());
     }
 
     @Test
diff --git a/server/src/test/java/com/vaadin/ui/PushConfigurationTransportTest.java b/server/src/test/java/com/vaadin/ui/PushConfigurationTransportTest.java
index 6111ccc65b..8841bc70bc 100644
--- a/server/src/test/java/com/vaadin/ui/PushConfigurationTransportTest.java
+++ b/server/src/test/java/com/vaadin/ui/PushConfigurationTransportTest.java
@@ -15,7 +15,10 @@
  */
 package com.vaadin.ui;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import org.junit.Test;
 
 import com.vaadin.server.VaadinRequest;
@@ -38,14 +41,13 @@ public class PushConfigurationTransportTest {
         };
         for (Transport transport : Transport.values()) {
             ui.getPushConfiguration().setTransport(transport);
-            Assert.assertEquals(ui.getPushConfiguration().getTransport(),
-                    transport);
+            assertEquals(ui.getPushConfiguration().getTransport(), transport);
 
             if (transport == Transport.WEBSOCKET_XHR) {
-                Assert.assertTrue(ui
+                assertTrue(ui
                         .getState().pushConfiguration.alwaysUseXhrForServerRequests);
             } else {
-                Assert.assertFalse(ui
+                assertFalse(ui
                         .getState().pushConfiguration.alwaysUseXhrForServerRequests);
             }
         }
diff --git a/server/src/test/java/com/vaadin/ui/RadioButtonGroupTest.java b/server/src/test/java/com/vaadin/ui/RadioButtonGroupTest.java
index b87d459517..fd2350685a 100644
--- a/server/src/test/java/com/vaadin/ui/RadioButtonGroupTest.java
+++ b/server/src/test/java/com/vaadin/ui/RadioButtonGroupTest.java
@@ -15,9 +15,12 @@
  */
 package com.vaadin.ui;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import java.util.concurrent.atomic.AtomicInteger;
 
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -42,7 +45,7 @@ public class RadioButtonGroupTest {
 
         radioButtonGroup.addSelectionListener(event -> {
             listenerCount.incrementAndGet();
-            Assert.assertFalse(event.isUserOriginated());
+            assertFalse(event.isUserOriginated());
         });
 
         radioButtonGroup.setValue("First");
@@ -51,7 +54,7 @@ public class RadioButtonGroupTest {
         radioButtonGroup.setValue(null);
         radioButtonGroup.setValue(null);
 
-        Assert.assertEquals(3, listenerCount.get());
+        assertEquals(3, listenerCount.get());
     }
 
     @Test
@@ -60,7 +63,7 @@ public class RadioButtonGroupTest {
 
         radioButtonGroup.addSelectionListener(event -> {
             listenerCount.incrementAndGet();
-            Assert.assertTrue(event.isUserOriginated());
+            assertTrue(event.isUserOriginated());
         });
 
         SelectionServerRpc rpc = ServerRpcManager.getRpcProxy(radioButtonGroup,
@@ -70,7 +73,7 @@ public class RadioButtonGroupTest {
         rpc.select(getItemKey("Second"));
         rpc.deselect(getItemKey("Second"));
 
-        Assert.assertEquals(3, listenerCount.get());
+        assertEquals(3, listenerCount.get());
     }
 
     private String getItemKey(String dataObject) {
diff --git a/server/src/test/java/com/vaadin/ui/RichTextAreaConstructorTest.java b/server/src/test/java/com/vaadin/ui/RichTextAreaConstructorTest.java
index b77690594c..212ce2da9f 100644
--- a/server/src/test/java/com/vaadin/ui/RichTextAreaConstructorTest.java
+++ b/server/src/test/java/com/vaadin/ui/RichTextAreaConstructorTest.java
@@ -15,29 +15,31 @@
  */
 package com.vaadin.ui;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+
 import org.junit.Test;
 import org.mockito.Mockito;
 
 import com.vaadin.data.HasValue;
-import static org.mockito.Mockito.never;
-import static org.mockito.Mockito.verify;
 
 public class RichTextAreaConstructorTest {
 
     @Test
     public void initiallyEmpty() {
         RichTextArea richTextArea = new RichTextArea();
-        Assert.assertTrue(richTextArea.isEmpty());
+        assertTrue(richTextArea.isEmpty());
     }
 
     @Test
     public void testValueConstructor_emptyAfterClear() {
         RichTextArea richTextArea = new RichTextArea(null, "foobar");
-        Assert.assertFalse(richTextArea.isEmpty());
+        assertFalse(richTextArea.isEmpty());
 
         richTextArea.clear();
-        Assert.assertTrue(richTextArea.isEmpty());
+        assertTrue(richTextArea.isEmpty());
     }
 
     @Test
diff --git a/server/src/test/java/com/vaadin/ui/RichTextAreaTest.java b/server/src/test/java/com/vaadin/ui/RichTextAreaTest.java
index 7c042df931..3c27ae9820 100644
--- a/server/src/test/java/com/vaadin/ui/RichTextAreaTest.java
+++ b/server/src/test/java/com/vaadin/ui/RichTextAreaTest.java
@@ -18,8 +18,10 @@ package com.vaadin.ui;
 import static com.vaadin.ui.ComponentTest.isDirty;
 import static com.vaadin.ui.ComponentTest.syncToClient;
 import static com.vaadin.ui.ComponentTest.updateDiffState;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.server.ClientConnector;
@@ -33,7 +35,7 @@ public class RichTextAreaTest {
     @Test
     public void initiallyEmpty() {
         RichTextArea tf = new RichTextArea();
-        Assert.assertTrue(tf.isEmpty());
+        assertTrue(tf.isEmpty());
     }
 
     @Test
@@ -41,7 +43,7 @@ public class RichTextAreaTest {
         RichTextArea tf = new RichTextArea();
         tf.setReadOnly(true);
         tf.setValue("foo");
-        Assert.assertEquals("foo", tf.getValue());
+        assertEquals("foo", tf.getValue());
     }
 
     @Test
@@ -64,8 +66,8 @@ public class RichTextAreaTest {
 
         // The real value will be sent back as long as the field is marked as
         // dirty and diffstate contains what the client has
-        Assert.assertEquals("foo", getDiffStateString(rta, "value"));
-        Assert.assertTrue("Component should be marked dirty", isDirty(rta));
+        assertEquals("foo", getDiffStateString(rta, "value"));
+        assertTrue("Component should be marked dirty", isDirty(rta));
     }
 
     @Test
@@ -78,7 +80,7 @@ public class RichTextAreaTest {
         updateDiffState(rta);
         ServerRpcManager.getRpcProxy(rta, RichTextAreaServerRpc.class)
                 .setText("foo");
-        Assert.assertEquals("foo", getDiffStateString(rta, "value"));
+        assertEquals("foo", getDiffStateString(rta, "value"));
     }
 
     private String getDiffStateString(ClientConnector connector, String key) {
@@ -92,7 +94,7 @@ public class RichTextAreaTest {
         tf.setValue("bar");
         tf.setReadOnly(true);
         tf.setValue("foo", true);
-        Assert.assertEquals("bar", tf.getValue());
+        assertEquals("bar", tf.getValue());
     }
 
     @Test(expected = NullPointerException.class)
@@ -105,9 +107,9 @@ public class RichTextAreaTest {
     public void emptyAfterClear() {
         RichTextArea tf = new RichTextArea();
         tf.setValue("foobar");
-        Assert.assertFalse(tf.isEmpty());
+        assertFalse(tf.isEmpty());
         tf.clear();
-        Assert.assertTrue(tf.isEmpty());
+        assertTrue(tf.isEmpty());
     }
 
 }
diff --git a/server/src/test/java/com/vaadin/ui/TextAreaConstructorTest.java b/server/src/test/java/com/vaadin/ui/TextAreaConstructorTest.java
index c090d86efe..0c89d53051 100644
--- a/server/src/test/java/com/vaadin/ui/TextAreaConstructorTest.java
+++ b/server/src/test/java/com/vaadin/ui/TextAreaConstructorTest.java
@@ -15,29 +15,31 @@
  */
 package com.vaadin.ui;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+
 import org.junit.Test;
 import org.mockito.Mockito;
 
 import com.vaadin.data.HasValue;
-import static org.mockito.Mockito.never;
-import static org.mockito.Mockito.verify;
 
 public class TextAreaConstructorTest {
 
     @Test
     public void initiallyEmpty() {
         TextArea textArea = new TextArea();
-        Assert.assertTrue(textArea.isEmpty());
+        assertTrue(textArea.isEmpty());
     }
 
     @Test
     public void testValueConstructor_emptyAfterClear() {
         TextArea textArea = new TextArea(null, "foobar");
-        Assert.assertFalse(textArea.isEmpty());
+        assertFalse(textArea.isEmpty());
 
         textArea.clear();
-        Assert.assertTrue(textArea.isEmpty());
+        assertTrue(textArea.isEmpty());
     }
 
     @Test
diff --git a/server/src/test/java/com/vaadin/ui/TextAreaTest.java b/server/src/test/java/com/vaadin/ui/TextAreaTest.java
index 6c3d5fecd5..110fa86eff 100644
--- a/server/src/test/java/com/vaadin/ui/TextAreaTest.java
+++ b/server/src/test/java/com/vaadin/ui/TextAreaTest.java
@@ -15,23 +15,25 @@
  */
 package com.vaadin.ui;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import org.junit.Test;
 
 public class TextAreaTest {
     @Test
     public void initiallyEmpty() {
         TextArea textArea = new TextArea();
-        Assert.assertTrue(textArea.isEmpty());
+        assertTrue(textArea.isEmpty());
     }
 
     @Test
     public void emptyAfterClear() {
         TextArea textArea = new TextArea();
         textArea.setValue("foobar");
-        Assert.assertFalse(textArea.isEmpty());
+        assertFalse(textArea.isEmpty());
         textArea.clear();
-        Assert.assertTrue(textArea.isEmpty());
+        assertTrue(textArea.isEmpty());
     }
 
 }
diff --git a/server/src/test/java/com/vaadin/ui/TextFieldConstructorTest.java b/server/src/test/java/com/vaadin/ui/TextFieldConstructorTest.java
index 3bcb457fec..d8b5e986cc 100644
--- a/server/src/test/java/com/vaadin/ui/TextFieldConstructorTest.java
+++ b/server/src/test/java/com/vaadin/ui/TextFieldConstructorTest.java
@@ -15,29 +15,31 @@
  */
 package com.vaadin.ui;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+
 import org.junit.Test;
 import org.mockito.Mockito;
 
 import com.vaadin.data.HasValue;
-import static org.mockito.Mockito.never;
-import static org.mockito.Mockito.verify;
 
 public class TextFieldConstructorTest {
 
     @Test
     public void initiallyEmpty() {
         TextField textField = new TextField();
-        Assert.assertTrue(textField.isEmpty());
+        assertTrue(textField.isEmpty());
     }
 
     @Test
     public void testValueConstructor_emptyAfterClear() {
         TextField textField = new TextField(null, "foobar");
-        Assert.assertFalse(textField.isEmpty());
+        assertFalse(textField.isEmpty());
 
         textField.clear();
-        Assert.assertTrue(textField.isEmpty());
+        assertTrue(textField.isEmpty());
     }
 
     @Test
diff --git a/server/src/test/java/com/vaadin/ui/UIInitRefreshTest.java b/server/src/test/java/com/vaadin/ui/UIInitRefreshTest.java
index 65bbc59a5b..a1b8394c7b 100644
--- a/server/src/test/java/com/vaadin/ui/UIInitRefreshTest.java
+++ b/server/src/test/java/com/vaadin/ui/UIInitRefreshTest.java
@@ -15,11 +15,14 @@
  */
 package com.vaadin.ui;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import java.util.Locale;
 
 import org.easymock.EasyMock;
 import org.easymock.IMocksControl;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -47,36 +50,36 @@ public class UIInitRefreshTest {
 
             initCalled = true;
 
-            Assert.assertEquals("foo", getPage().getUriFragment());
-            Assert.assertEquals(100, getPage().getBrowserWindowWidth());
-            Assert.assertEquals(100, getPage().getBrowserWindowHeight());
+            assertEquals("foo", getPage().getUriFragment());
+            assertEquals(100, getPage().getBrowserWindowWidth());
+            assertEquals(100, getPage().getBrowserWindowHeight());
 
-            Assert.assertFalse(fragmentChangeCalled);
-            Assert.assertFalse(browserWindowResizeCalled);
+            assertFalse(fragmentChangeCalled);
+            assertFalse(browserWindowResizeCalled);
         }
 
         @Override
         protected void refresh(VaadinRequest request) {
             refreshCalled = true;
 
-            Assert.assertEquals("bar", getPage().getUriFragment());
-            Assert.assertEquals(200, getPage().getBrowserWindowWidth());
-            Assert.assertEquals(200, getPage().getBrowserWindowHeight());
+            assertEquals("bar", getPage().getUriFragment());
+            assertEquals(200, getPage().getBrowserWindowWidth());
+            assertEquals(200, getPage().getBrowserWindowHeight());
 
-            Assert.assertFalse(fragmentChangeCalled);
-            Assert.assertFalse(browserWindowResizeCalled);
+            assertFalse(fragmentChangeCalled);
+            assertFalse(browserWindowResizeCalled);
         }
 
         @Override
         public void browserWindowResized(BrowserWindowResizeEvent event) {
-            Assert.assertEquals(200, event.getWidth());
-            Assert.assertEquals(200, event.getHeight());
+            assertEquals(200, event.getWidth());
+            assertEquals(200, event.getHeight());
             browserWindowResizeCalled = true;
         }
 
         @Override
         public void uriFragmentChanged(UriFragmentChangedEvent event) {
-            Assert.assertEquals("bar", event.getUriFragment());
+            assertEquals("bar", event.getUriFragment());
             fragmentChangeCalled = true;
         }
     }
@@ -117,14 +120,14 @@ public class UIInitRefreshTest {
         ui.setSession(session);
         ui.doInit(initRequest, 0, "");
 
-        Assert.assertTrue(initCalled);
-        Assert.assertFalse(fragmentChangeCalled);
-        Assert.assertFalse(browserWindowResizeCalled);
+        assertTrue(initCalled);
+        assertFalse(fragmentChangeCalled);
+        assertFalse(browserWindowResizeCalled);
 
         ui.doRefresh(reinitRequest);
 
-        Assert.assertTrue(refreshCalled);
-        Assert.assertTrue(fragmentChangeCalled);
-        Assert.assertTrue(browserWindowResizeCalled);
+        assertTrue(refreshCalled);
+        assertTrue(fragmentChangeCalled);
+        assertTrue(browserWindowResizeCalled);
     }
 }
diff --git a/server/src/test/java/com/vaadin/ui/UITest.java b/server/src/test/java/com/vaadin/ui/UITest.java
index 8bc3c98470..886dd38087 100644
--- a/server/src/test/java/com/vaadin/ui/UITest.java
+++ b/server/src/test/java/com/vaadin/ui/UITest.java
@@ -1,5 +1,9 @@
 package com.vaadin.ui;
 
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.fail;
+
 import java.lang.ref.WeakReference;
 import java.util.Properties;
 import java.util.concurrent.ConcurrentLinkedQueue;
@@ -9,7 +13,6 @@ import java.util.concurrent.locks.ReentrantLock;
 
 import javax.servlet.ServletConfig;
 
-import org.junit.Assert;
 import org.junit.Test;
 import org.mockito.Mockito;
 
@@ -132,16 +135,16 @@ public class UITest {
         if (websocketThread.isAlive() || uiDisconnectThread.isAlive()) {
             websocketThread.interrupt();
             uiDisconnectThread.interrupt();
-            Assert.fail("Threads are still running");
+            fail("Threads are still running");
         }
         if (!exceptions.isEmpty()) {
             for (Exception e : exceptions) {
                 e.printStackTrace();
             }
-            Assert.fail("There were exceptions in the threads");
+            fail("There were exceptions in the threads");
         }
 
-        Assert.assertNull(ui.getSession());
+        assertNull(ui.getSession());
 
         // PushConnection is set to null in another thread. We need to wait for
         // that to happen
@@ -152,7 +155,7 @@ public class UITest {
 
             Thread.sleep(500);
         }
-        Assert.assertNull(ui.getPushConnection());
+        assertNull(ui.getPushConnection());
 
     }
 
@@ -195,7 +198,7 @@ public class UITest {
         CurrentInstanceTest.waitUntilGarbageCollected(contentOnlyOnServer);
         // Should not clean references for connectors available in the browser
         // until the session is unlocked and we know if it has been moved
-        Assert.assertNotNull(contentSentToClient.get());
+        assertNotNull(contentSentToClient.get());
         session.unlock();
         CurrentInstanceTest.waitUntilGarbageCollected(contentSentToClient);
     }
diff --git a/server/src/test/java/com/vaadin/ui/VerticalSplitPanelTest.java b/server/src/test/java/com/vaadin/ui/VerticalSplitPanelTest.java
index d77f307d49..bc732177f4 100644
--- a/server/src/test/java/com/vaadin/ui/VerticalSplitPanelTest.java
+++ b/server/src/test/java/com/vaadin/ui/VerticalSplitPanelTest.java
@@ -15,7 +15,8 @@
  */
 package com.vaadin.ui;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+
 import org.junit.Test;
 
 import com.vaadin.shared.ui.splitpanel.VerticalSplitPanelState;
@@ -24,7 +25,7 @@ public class VerticalSplitPanelTest {
 
     @Test
     public void primaryStyleName() {
-        Assert.assertEquals(new VerticalSplitPanelState().primaryStyleName,
+        assertEquals(new VerticalSplitPanelState().primaryStyleName,
                 new VerticalSplitPanel().getPrimaryStyleName());
     }
 }
diff --git a/server/src/test/java/com/vaadin/ui/components/grid/StaticSectionTest.java b/server/src/test/java/com/vaadin/ui/components/grid/StaticSectionTest.java
index 1223cfaef8..8ae35e72a3 100644
--- a/server/src/test/java/com/vaadin/ui/components/grid/StaticSectionTest.java
+++ b/server/src/test/java/com/vaadin/ui/components/grid/StaticSectionTest.java
@@ -15,12 +15,13 @@
  */
 package com.vaadin.ui.components.grid;
 
+import static org.junit.Assert.assertEquals;
+
 import java.util.Arrays;
 import java.util.HashSet;
 
 import org.jsoup.nodes.Element;
 import org.jsoup.parser.Tag;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -129,9 +130,9 @@ public class StaticSectionTest {
 
         staticRow.writeDesign(container, null);
 
-        Assert.assertEquals(2, container.children().size());
-        Assert.assertEquals("col1,col2", container.child(0).attr("column-ids"));
-        Assert.assertEquals("col3", container.child(1).attr("column-ids"));
+        assertEquals(2, container.children().size());
+        assertEquals("col1,col2", container.child(0).attr("column-ids"));
+        assertEquals("col3", container.child(1).attr("column-ids"));
     }
 
 }
diff --git a/server/src/test/java/com/vaadin/ui/declarative/DesignTest.java b/server/src/test/java/com/vaadin/ui/declarative/DesignTest.java
index 769a02dedc..928eb3acb6 100644
--- a/server/src/test/java/com/vaadin/ui/declarative/DesignTest.java
+++ b/server/src/test/java/com/vaadin/ui/declarative/DesignTest.java
@@ -15,6 +15,8 @@
  */
 package com.vaadin.ui.declarative;
 
+import static org.junit.Assert.assertEquals;
+
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.lang.reflect.Field;
@@ -27,7 +29,6 @@ import org.jsoup.nodes.Element;
 import org.jsoup.nodes.Node;
 import org.jsoup.nodes.TextNode;
 import org.junit.AfterClass;
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.ui.Component;
@@ -62,7 +63,7 @@ public class DesignTest {
         String cp1251Html = getHtml();
         setUtf8Charset();
         String utf8Html = getHtml();
-        Assert.assertEquals(
+        assertEquals(
                 "Html written with UTF-8 as default encoding "
                         + "differs from html written with cp1251 encoding",
                 cp1251Html, utf8Html);
@@ -74,7 +75,7 @@ public class DesignTest {
             IllegalArgumentException, IllegalAccessException {
         setCp1251Charset();
         String cp1251Html = getHtml();
-        Assert.assertEquals(
+        assertEquals(
                 "Non ascii string parsed from serialized HTML "
                         + "differs from expected",
                 NON_ASCII_STRING, getHtmlLabelValue(cp1251Html));
@@ -86,7 +87,7 @@ public class DesignTest {
             IllegalArgumentException, IllegalAccessException {
         setUtf8Charset();
         String utf8 = getHtml();
-        Assert.assertEquals(
+        assertEquals(
                 "Non ascii string parsed from serialized HTML "
                         + "differs from expected",
                 NON_ASCII_STRING, getHtmlLabelValue(utf8));
diff --git a/server/src/test/java/com/vaadin/util/CurrentInstanceTest.java b/server/src/test/java/com/vaadin/util/CurrentInstanceTest.java
index dd4cc3f543..74b8ce7e6d 100644
--- a/server/src/test/java/com/vaadin/util/CurrentInstanceTest.java
+++ b/server/src/test/java/com/vaadin/util/CurrentInstanceTest.java
@@ -15,7 +15,10 @@
  */
 package com.vaadin.util;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
+import static org.junit.Assert.fail;
 
 import java.lang.ref.WeakReference;
 import java.lang.reflect.Field;
@@ -27,7 +30,6 @@ import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
 
 import org.easymock.EasyMock;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -52,8 +54,7 @@ public class CurrentInstanceTest {
     @Test
     public void testClearedAfterRemove() throws Exception {
         CurrentInstance.set(CurrentInstanceTest.class, this);
-        Assert.assertEquals(this,
-                CurrentInstance.get(CurrentInstanceTest.class));
+        assertEquals(this, CurrentInstance.get(CurrentInstanceTest.class));
         CurrentInstance.set(CurrentInstanceTest.class, null);
 
         assertCleared();
@@ -62,8 +63,7 @@ public class CurrentInstanceTest {
     @Test
     public void testClearedWithClearAll() throws Exception {
         CurrentInstance.set(CurrentInstanceTest.class, this);
-        Assert.assertEquals(this,
-                CurrentInstance.get(CurrentInstanceTest.class));
+        assertEquals(this, CurrentInstance.get(CurrentInstanceTest.class));
         CurrentInstance.clearAll();
 
         assertCleared();
@@ -71,7 +71,7 @@ public class CurrentInstanceTest {
 
     private void assertCleared() throws SecurityException, NoSuchFieldException,
             IllegalAccessException {
-        Assert.assertNull(getInternalCurrentInstanceVariable().get());
+        assertNull(getInternalCurrentInstanceVariable().get());
     }
 
     private ThreadLocal<Map<Class<?>, CurrentInstance>> getInternalCurrentInstanceVariable()
@@ -156,7 +156,7 @@ public class CurrentInstanceTest {
 
         CurrentInstance.restoreInstances(previous);
 
-        Assert.assertNull(VaadinSession.getCurrent());
+        assertNull(VaadinSession.getCurrent());
     }
 
     public static void waitUntilGarbageCollected(WeakReference<?> ref)
@@ -168,7 +168,7 @@ public class CurrentInstanceTest {
             }
             Thread.sleep(100);
         }
-        Assert.fail("Value was not garbage collected.");
+        fail("Value was not garbage collected.");
     }
 
     @Test
@@ -177,10 +177,10 @@ public class CurrentInstanceTest {
         CurrentInstance.clearAll();
         CurrentInstance.set(CurrentInstanceTest.class, this);
 
-        Assert.assertNotNull(CurrentInstance.get(CurrentInstanceTest.class));
+        assertNotNull(CurrentInstance.get(CurrentInstanceTest.class));
 
         Callable<Void> runnable = () -> {
-            Assert.assertNull(CurrentInstance.get(CurrentInstanceTest.class));
+            assertNull(CurrentInstance.get(CurrentInstanceTest.class));
             return null;
         };
         ExecutorService service = Executors.newSingleThreadExecutor();
diff --git a/server/src/test/java/com/vaadin/util/EncodeUtilTest.java b/server/src/test/java/com/vaadin/util/EncodeUtilTest.java
index 7bac539968..59efec59ad 100644
--- a/server/src/test/java/com/vaadin/util/EncodeUtilTest.java
+++ b/server/src/test/java/com/vaadin/util/EncodeUtilTest.java
@@ -15,18 +15,19 @@
  */
 package com.vaadin.util;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
+
 import org.junit.Test;
 
 public class EncodeUtilTest {
     @Test
     public void rfc5987Encode() {
-        Assert.assertEquals("A", EncodeUtil.rfc5987Encode("A"));
-        Assert.assertEquals("%20", EncodeUtil.rfc5987Encode(" "));
-        Assert.assertEquals("%c3%a5", EncodeUtil.rfc5987Encode("å"));
-        Assert.assertEquals("%e6%97%a5", EncodeUtil.rfc5987Encode("日"));
+        assertEquals("A", EncodeUtil.rfc5987Encode("A"));
+        assertEquals("%20", EncodeUtil.rfc5987Encode(" "));
+        assertEquals("%c3%a5", EncodeUtil.rfc5987Encode("å"));
+        assertEquals("%e6%97%a5", EncodeUtil.rfc5987Encode("日"));
 
-        Assert.assertEquals("A" + "%20" + "%c3%a5" + "%e6%97%a5",
+        assertEquals("A" + "%20" + "%c3%a5" + "%e6%97%a5",
                 EncodeUtil.rfc5987Encode("A å日"));
     }
 }
diff --git a/server/src/test/java/com/vaadin/util/ReflectToolsTest.java b/server/src/test/java/com/vaadin/util/ReflectToolsTest.java
index 353bf0972c..6fba5d761f 100644
--- a/server/src/test/java/com/vaadin/util/ReflectToolsTest.java
+++ b/server/src/test/java/com/vaadin/util/ReflectToolsTest.java
@@ -15,39 +15,40 @@
  */
 package com.vaadin.util;
 
+import static org.junit.Assert.assertSame;
+
 import java.io.Serializable;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 public class ReflectToolsTest implements Serializable {
     @Test
     public void findCommonBaseType_sameType() {
-        Assert.assertSame(Number.class,
+        assertSame(Number.class,
                 ReflectTools.findCommonBaseType(Number.class, Number.class));
     }
 
     @Test
     public void findCommonBaseType_aExtendsB() {
-        Assert.assertSame(Number.class,
+        assertSame(Number.class,
                 ReflectTools.findCommonBaseType(Integer.class, Number.class));
     }
 
     @Test
     public void findCommonBaseType_bExtendsA() {
-        Assert.assertSame(Number.class,
+        assertSame(Number.class,
                 ReflectTools.findCommonBaseType(Number.class, Integer.class));
     }
 
     @Test
     public void findCommonBaseType_commonBase() {
-        Assert.assertSame(Number.class,
+        assertSame(Number.class,
                 ReflectTools.findCommonBaseType(Double.class, Integer.class));
     }
 
     @Test
     public void findCommonBaseType_noCommonBase() {
-        Assert.assertSame(Object.class,
+        assertSame(Object.class,
                 ReflectTools.findCommonBaseType(String.class, Number.class));
     }
 }