Test status quo for finding multiple composed annotations

This commit introduces tests that verify the status quo for finding
multiple merged composed annotations on a single annotated element.

Issue: SPR-13486

Author: sbrannen

spring-core/src/test/java/org/springframework/core/annotation/AnnotatedElementUtilsTests.java

@@ -55,6 +55,8 @@
  * @author Sam Brannen
  * @author Rossen Stoyanchev
  * @since 4.0.3
+ * @see AnnotationUtilsTests
+ * @see MultipleComposedAnnotationsOnSingleAnnotatedElementTests
  */
 public class AnnotatedElementUtilsTests {
 

spring-core/src/test/java/org/springframework/core/annotation/MultipleComposedAnnotationsOnSingleAnnotatedElementTests.java

@@ -0,0 +1,125 @@
+/*
+ * Copyright 2002-2016 the original author or authors.
+ *
+ * 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 org.springframework.core.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Inherited;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+import java.lang.reflect.AnnotatedElement;
+
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+import static org.springframework.core.annotation.AnnotatedElementUtils.*;
+
+/**
+ * Unit tests that verify support for finding multiple composed annotations on
+ * a single annotated element.
+ *
+ * <p>See <a href="https://jira.spring.io/browse/SPR-13486">SPR-13486</a>.
+ *
+ * @author Sam Brannen
+ * @since 4.3
+ * @see AnnotatedElementUtils
+ * @see AnnotatedElementUtilsTests
+ */
+public class MultipleComposedAnnotationsOnSingleAnnotatedElementTests {
+
+	@Test
+	public void multipleComposedAnnotationsOnClass() {
+		assertMultipleComposedAnnotations(MultipleCachesClass.class);
+	}
+
+	@Test
+	public void multipleComposedAnnotationsOnMethod() throws Exception {
+		AnnotatedElement element = getClass().getDeclaredMethod("multipleCachesMethod");
+		assertMultipleComposedAnnotations(element);
+	}
+
+	private void assertMultipleComposedAnnotations(AnnotatedElement element) {
+		assertNotNull(element);
+
+		// Prerequisites
+		FooCache fooCache = element.getAnnotation(FooCache.class);
+		BarCache barCache = element.getAnnotation(BarCache.class);
+		assertNotNull(fooCache);
+		assertNotNull(barCache);
+		assertEquals("fooKey", fooCache.key());
+		assertEquals("barKey", barCache.key());
+
+		// Assert the status quo for finding the 1st merged annotation.
+		Cacheable cacheable = findMergedAnnotation(element, Cacheable.class);
+		assertNotNull(cacheable);
+		assertEquals("fooCache", cacheable.value());
+		assertEquals("fooKey", cacheable.key());
+
+		// TODO Introduce findMergedAnnotations(...) in AnnotatedElementUtils.
+
+		// assertEquals("barCache", cacheable.value());
+		// assertEquals("barKey", cacheable.key());
+	}
+
+
+	// -------------------------------------------------------------------------
+
+	/**
+	 * Mock of {@code org.springframework.cache.annotation.Cacheable}.
+	 */
+	@Target({ ElementType.METHOD, ElementType.TYPE })
+	@Retention(RetentionPolicy.RUNTIME)
+	@Inherited
+	@interface Cacheable {
+
+		String value();
+
+		String key() default "";
+	}
+
+	@Cacheable("fooCache")
+	@Target({ ElementType.METHOD, ElementType.TYPE })
+	@Retention(RetentionPolicy.RUNTIME)
+	@Inherited
+	@interface FooCache {
+
+		@AliasFor(annotation = Cacheable.class)
+		String key() default "";
+	}
+
+	@Cacheable("barCache")
+	@Target({ ElementType.METHOD, ElementType.TYPE })
+	@Retention(RetentionPolicy.RUNTIME)
+	@Inherited
+	@interface BarCache {
+
+		@AliasFor(annotation = Cacheable.class)
+		String key();
+	}
+
+	@FooCache(key = "fooKey")
+	@BarCache(key = "barKey")
+	private static class MultipleCachesClass {
+	}
+
+
+	@FooCache(key = "fooKey")
+	@BarCache(key = "barKey")
+	private void multipleCachesMethod() {
+	}
+
+}