Provide a shorthand for the HasValue::clear() method. (#94)

* Provide a shorthand for the HasValue::clear() method.

Fixes vaadin/framework8-issues#496

2 files changed, 60 insertions, 0 deletions

diff --git a/server/src/main/java/com/vaadin/data/HasValue.java b/server/src/main/java/com/vaadin/data/HasValue.java
index 1a612dbb80..a7fe8901db 100644
--- a/server/src/main/java/com/vaadin/data/HasValue.java
+++ b/server/src/main/java/com/vaadin/data/HasValue.java
@@ -257,4 +257,17 @@ public interface HasValue<V> extends Serializable {
      *         not.
      */
     public boolean isReadOnly();
+
+    /**
+     * Resets the value to the empty one.
+     * <p>
+     * This is just a shorthand for resetting the value, see the methods
+     * {@link #setValue(Object)} and {@link #getEmptyValue()}.
+     * 
+     * @see #setValue(Object)
+     * @see #getEmptyValue()
+     */
+    public default void clear() {
+        setValue(getEmptyValue());
+    }
 }
diff --git a/server/src/test/java/com/vaadin/server/data/HasValueTest.java b/server/src/test/java/com/vaadin/server/data/HasValueTest.java
new file mode 100644
index 0000000000..cc3815d0e5
--- /dev/null
+++ b/server/src/test/java/com/vaadin/server/data/HasValueTest.java
@@ -0,0 +1,47 @@
+/*
+ * Copyright 2000-2016 Vaadin Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.vaadin.server.data;
+
+import org.junit.Test;
+import org.mockito.Mockito;
+
+import com.vaadin.data.HasValue;
+
+/**
+ * @author Vaadin Ltd
+ *
+ */
+public class HasValueTest {
+
+    public abstract static class TestHasValue implements HasValue<String> {
+        @Override
+        public void clear() {
+            HasValue.super.clear();
+        }
+    }
+
+    @Test
+    public void clear() {
+        TestHasValue hasValue = Mockito.mock(TestHasValue.class);
+        Mockito.doCallRealMethod().when(hasValue).clear();
+        String value = "foo";
+        Mockito.when(hasValue.getEmptyValue()).thenReturn(value);
+
+        hasValue.clear();
+
+        Mockito.verify(hasValue).setValue(value);
+    }
+}