Added convenience method to access property annotations

Author: SQiShER

src/main/java/de/danielbechler/diff/accessor/PropertyAccessor.java

@@ -199,6 +199,21 @@ public Set<Annotation> getReadMethodAnnotations()
 		return new LinkedHashSet<Annotation>(Arrays.asList(readMethod.getAnnotations()));
 	}
 
+	public <T extends Annotation> T getReadMethodAnnotation(final Class<T> annotationClass)
+	{
+		final Set<? extends Annotation> annotations = getReadMethodAnnotations();
+		assert (annotations != null) : "Something is wrong here. " +
+				"The contract of getReadAnnotations() guarantees a non-null return value.";
+		for (final Annotation annotation : annotations)
+		{
+			if (annotationClass.isAssignableFrom(annotation.annotationType()))
+			{
+				return annotationClass.cast(annotation);
+			}
+		}
+		return null;
+	}
+
 	@Override
 	public String toString()
 	{

src/main/java/de/danielbechler/diff/node/DefaultNode.java

@@ -294,6 +294,15 @@ public Set<Annotation> getPropertyAnnotations()
 		return unmodifiableSet(Collections.<Annotation>emptySet());
 	}
 
+	public <T extends Annotation> T getPropertyAnnotation(final Class<T> annotationClass)
+	{
+		if (accessor instanceof PropertyAccessor)
+		{
+			return ((PropertyAccessor) accessor).getReadMethodAnnotation(annotationClass);
+		}
+		return null;
+	}
+
 	public final boolean isRootNode()
 	{
 		return accessor instanceof RootAccessor;

src/main/java/de/danielbechler/diff/node/Node.java

@@ -198,4 +198,7 @@ public enum State
 	 * @return A set of annotations of this nodes property getter or an empty set.
 	 */
 	Set<Annotation> getPropertyAnnotations();
+
+	<T extends Annotation> T getPropertyAnnotation(Class<T> annotationClass);
+
 }

src/test/java/de/danielbechler/diff/accessor/PropertyAccessorShould.java

@@ -17,14 +17,13 @@
 package de.danielbechler.diff.accessor;
 
 import de.danielbechler.diff.accessor.exception.*;
+import de.danielbechler.diff.annotation.*;
 import de.danielbechler.diff.mock.*;
 import de.danielbechler.diff.path.*;
-import org.fest.assertions.api.*;
 import org.testng.annotations.*;
 
 import java.lang.annotation.*;
 import java.lang.reflect.*;
-import java.util.*;
 
 import static java.util.Arrays.*;
 import static org.fest.assertions.api.Assertions.*;
@@ -152,17 +151,39 @@ public void includes_accessor_type_in_string_representation()
 	}
 
 	@Test
-	public void returns_annotations_of_getter_as_set() throws Exception
+	public void returns_annotations_of_property_getter() throws Exception
 	{
 		accessor = PropertyAccessorBuilder.forPropertyOf(ObjectWithAnnotatedProperty.class)
 										  .property("value", String.class)
 										  .readOnly(false)
 										  .build();
 		final Annotation[] expectedAnnotations = ObjectWithAnnotatedProperty.class.getMethod("getValue")
 																				  .getAnnotations();
-		Assertions.assertThat(expectedAnnotations).hasSize(2);
+		assertThat(expectedAnnotations).hasSize(2);
+		assertThat(accessor.getReadMethodAnnotations()).containsAll(asList(expectedAnnotations));
+	}
 
-		final Set<Annotation> set = accessor.getReadMethodAnnotations();
-		Assertions.assertThat(set).containsAll(asList(expectedAnnotations));
+	@Test
+	public void returns_specific_annotation_of_property_getter() throws Exception
+	{
+		accessor = PropertyAccessorBuilder.forPropertyOf(ObjectWithAnnotatedProperty.class)
+										  .property("value", String.class)
+										  .readOnly(false)
+										  .build();
+		final ObjectDiffProperty expectedAnnotation = ObjectWithAnnotatedProperty.class.getMethod("getValue")
+																					   .getAnnotation(ObjectDiffProperty.class);
+		assertThat(expectedAnnotation).isNotNull();
+		final ObjectDiffProperty annotation = accessor.getReadMethodAnnotation(ObjectDiffProperty.class);
+		assertThat(annotation).isEqualTo(expectedAnnotation);
+	}
+
+	@Test
+	public void returns_null_if_specific_annotation_of_property_getter_does_not_exist() throws Exception
+	{
+		accessor = PropertyAccessorBuilder.forPropertyOf(ObjectWithAnnotatedProperty.class)
+										  .property("value", String.class)
+										  .readOnly(false)
+										  .build();
+		assertThat(accessor.getReadMethodAnnotation(Override.class)).isNull();
 	}
 }

src/test/java/de/danielbechler/diff/node/DefaultNodeTest.java

@@ -17,6 +17,7 @@
 package de.danielbechler.diff.node;
 
 import de.danielbechler.diff.accessor.*;
+import de.danielbechler.diff.mock.*;
 import de.danielbechler.diff.path.*;
 import org.fest.assertions.api.*;
 import org.hamcrest.core.*;
@@ -191,4 +192,25 @@ public void testShould_return_empty_set_of_property_annotations_if_accessor_is_n
 
 		Assertions.assertThat(annotations).containsAll(Arrays.asList(annotation));
 	}
+
+	@Test
+	public void test_get_property_annotation_should_delegate_call_to_property_accessor()
+	{
+		final PropertyAccessor propertyAccessor = mock(PropertyAccessor.class);
+		when(propertyAccessor.getReadMethodAnnotation(ObjectDiffTest.class)).thenReturn(null);
+
+		new DefaultNode(propertyAccessor, Object.class).getPropertyAnnotation(ObjectDiffTest.class);
+
+		verify(propertyAccessor, times(1)).getReadMethodAnnotation(ObjectDiffTest.class);
+	}
+
+	@Test
+	public void test_get_property_annotation_should_return_null_if_accessor_is_not_property_accessor()
+	{
+		final Accessor propertyAccessor = mock(Accessor.class);
+
+		final ObjectDiffTest annotation = new DefaultNode(propertyAccessor, Object.class).getPropertyAnnotation(ObjectDiffTest.class);
+
+		assertThat(annotation).isNull();
+	}
 }