Correctly reset DataCommunicator when its DataProvider is changed (#8138)

* Correctly reset DataCommunicator when its DataProvider is changed

* Improve ReplaceDataProviderTest

* Remove return type from AbstractListing.readItems

3 files changed, 113 insertions, 6 deletions

diff --git a/server/src/test/java/com/vaadin/data/provider/ReplaceDataProviderTest.java b/server/src/test/java/com/vaadin/data/provider/ReplaceDataProviderTest.java
new file mode 100644
index 0000000000..0510022e5e
--- /dev/null
+++ b/server/src/test/java/com/vaadin/data/provider/ReplaceDataProviderTest.java
@@ -0,0 +1,110 @@
+package com.vaadin.data.provider;
+
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
+
+import java.util.List;
+import java.util.function.IntFunction;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+import org.junit.Test;
+
+import com.vaadin.server.SerializablePredicate;
+
+public class ReplaceDataProviderTest {
+
+    public static class BeanWithEquals extends Bean {
+
+        BeanWithEquals(int id) {
+            super(id);
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) {
+                return true;
+            }
+            if (o == null || getClass() != o.getClass()) {
+                return false;
+            }
+
+            BeanWithEquals that = (BeanWithEquals) o;
+
+            return id == that.id;
+        }
+
+        @Override
+        public int hashCode() {
+            return id;
+        }
+    }
+
+    public static class Bean {
+        protected final int id;
+        private final String fluff;
+
+        Bean(int id) {
+            this.id = id;
+            this.fluff = "Fluff #" + id;
+        }
+
+        public int getId() {
+            return id;
+        }
+
+        @SuppressWarnings("unused")
+        public String getFluff() {
+            return fluff;
+        }
+
+    }
+
+    @Test
+    public void testBeanEquals() {
+        doTest(BeanWithEquals::new);
+    }
+
+    @Test
+    public void testBeanSame() {
+        doTest(Bean::new);
+    }
+
+    private <SOME_BEAN> void doTest(IntFunction<SOME_BEAN> beanConstructor) {
+
+        DataCommunicator<SOME_BEAN, SerializablePredicate<SOME_BEAN>> dataCommunicator = new DataCommunicator<>();
+
+        List<SOME_BEAN> beans1 = createCollection(beanConstructor);
+
+        ListDataProvider<SOME_BEAN> dataProvider = new ListDataProvider<>(
+                beans1);
+
+        dataCommunicator.setDataProvider(dataProvider);
+        dataCommunicator.pushData(1, beans1.stream());
+
+        SOME_BEAN bean1_17 = beans1.get(17);
+        String key1_17 = dataCommunicator.getKeyMapper().key(bean1_17);
+
+        assertSame(bean1_17, dataCommunicator.getKeyMapper().get(key1_17));
+
+        List<SOME_BEAN> beans2 = createCollection(beanConstructor);
+
+        dataProvider = new ListDataProvider<>(beans2);
+        dataCommunicator.setDataProvider(dataProvider);
+        dataCommunicator.pushData(1, beans2.stream());
+
+        SOME_BEAN bean2_17 = beans2.get(17);
+        String key2_17 = dataCommunicator.getKeyMapper().key(bean2_17);
+
+        assertSame(bean2_17, dataCommunicator.getKeyMapper().get(key2_17));
+        assertNotEquals(key2_17, key1_17);
+        assertNull(dataCommunicator.getKeyMapper().get(key1_17));
+    }
+
+    private <SOME_BEAN> List<SOME_BEAN> createCollection(
+            IntFunction<SOME_BEAN> beanConstructor) {
+        return IntStream.range(1, 100).mapToObj(beanConstructor)
+                .collect(Collectors.toList());
+    }
+}
diff --git a/server/src/test/java/com/vaadin/ui/AbstractListingTest.java b/server/src/test/java/com/vaadin/ui/AbstractListingTest.java
index 819ed9feb3..212a15f32f 100644
--- a/server/src/test/java/com/vaadin/ui/AbstractListingTest.java
+++ b/server/src/test/java/com/vaadin/ui/AbstractListingTest.java
@@ -40,9 +40,8 @@ public class AbstractListingTest {
         }
 
         @Override
-        protected List<String> readItems(Element design,
+        protected void readItems(Element design,
                 DesignContext context) {
-            return null;
         }
 
         @Override
diff --git a/server/src/test/java/com/vaadin/ui/AbstractSingleSelectTest.java b/server/src/test/java/com/vaadin/ui/AbstractSingleSelectTest.java
index 1b814921e7..9bbcc2ca43 100644
--- a/server/src/test/java/com/vaadin/ui/AbstractSingleSelectTest.java
+++ b/server/src/test/java/com/vaadin/ui/AbstractSingleSelectTest.java
@@ -60,9 +60,8 @@ public class AbstractSingleSelectTest {
         }
 
         @Override
-        protected List<Person> readItems(Element design,
+        protected void readItems(Element design,
                 DesignContext context) {
-            return null;
         }
 
         @Override
@@ -254,9 +253,8 @@ public class AbstractSingleSelectTest {
             }
 
             @Override
-            protected List<String> readItems(Element design,
+            protected void readItems(Element design,
                     DesignContext context) {
-                return null;
             }
         };