Support @Configuration as meta-annotation in the TCF

Spring Framework 4.0 introduced support for using test-related
annotations as meta-annotations in the Spring TestContext Framework
(TCF) in order to create custom composed annotations within a test
suite; however, the detection of default @Configuration classes in test
classes was not updated to search for @Configuration declared as a
meta-annotation. Specifically, AnnotationConfigContextLoaderUtils
invokes Class.isAnnotated() which only searches for annotations
declared directly on the class in question.

This commit addresses this issue by refactoring the
isDefaultConfigurationClassCandidate() method in
AnnotationConfigContextLoaderUtils so that it uses
AnnotationUtils.findAnnotation() instead of Class.isAnnotated() for
detecting the presence of the @Configuration annotation, either
directly or as a meta-annotation.

Issue: SPR-12659

spring-test/src/main/java/org/springframework/test/context/support/AnnotationConfigContextLoaderUtils.java

@@ -24,6 +24,7 @@ import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
 import org.springframework.context.annotation.Configuration;
+import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.test.context.SmartContextLoader;
 import org.springframework.util.Assert;
 
@@ -95,13 +96,14 @@ public abstract class AnnotationConfigContextLoaderUtils {
 	 * <li>must not be {@code private}</li>
 	 * <li>must not be {@code final}</li>
 	 * <li>must be {@code static}</li>
-	 * <li>must be annotated with {@code @Configuration}</li>
+	 * <li>must be annotated or meta-annotated with {@code @Configuration}</li>
 	 * </ul>
 	 * @param clazz the class to check
 	 * @return {@code true} if the supplied class meets the candidate criteria
 	 */
 	private static boolean isDefaultConfigurationClassCandidate(Class<?> clazz) {
-		return (clazz != null && isStaticNonPrivateAndNonFinal(clazz) && clazz.isAnnotationPresent(Configuration.class));
+		return (clazz != null && isStaticNonPrivateAndNonFinal(clazz) &&
+				(AnnotationUtils.findAnnotation(clazz, Configuration.class) != null));
 	}
 
 	private static boolean isStaticNonPrivateAndNonFinal(Class<?> clazz) {

spring-test/src/test/java/org/springframework/test/context/support/AnnotationConfigContextLoaderUtilsTests.java

@@ -0,0 +1,89 @@
+/*
+ * Copyright 2002-2015 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.test.context.support;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.junit.Test;
+import org.springframework.context.annotation.Configuration;
+
+import static org.junit.Assert.*;
+import static org.springframework.test.context.support.AnnotationConfigContextLoaderUtils.*;
+
+/**
+ * Unit tests for {@link AnnotationConfigContextLoaderUtils}.
+ *
+ * @author Sam Brannen
+ * @since 4.1.5
+ */
+public class AnnotationConfigContextLoaderUtilsTests {
+
+	@Test(expected = IllegalArgumentException.class)
+	public void detectDefaultConfigurationClassesWithNullDeclaringClass() {
+		detectDefaultConfigurationClasses(null);
+	}
+
+	@Test
+	public void detectDefaultConfigurationClassesWithoutConfigurationClass() {
+		Class<?>[] configClasses = detectDefaultConfigurationClasses(NoConfigTestCase.class);
+		assertNotNull(configClasses);
+		assertEquals(0, configClasses.length);
+	}
+
+	@Test
+	public void detectDefaultConfigurationClassesWithExplicitConfigurationAnnotation() {
+		Class<?>[] configClasses = detectDefaultConfigurationClasses(ExplicitConfigTestCase.class);
+		assertNotNull(configClasses);
+		assertArrayEquals(new Class<?>[] { ExplicitConfigTestCase.Config.class }, configClasses);
+	}
+
+	@Test
+	public void detectDefaultConfigurationClassesWithConfigurationMetaAnnotation() {
+		Class<?>[] configClasses = detectDefaultConfigurationClasses(MetaAnnotatedConfigTestCase.class);
+		assertNotNull(configClasses);
+		assertArrayEquals(new Class<?>[] { MetaAnnotatedConfigTestCase.Config.class }, configClasses);
+	}
+
+
+	private static class NoConfigTestCase {
+
+	}
+
+	private static class ExplicitConfigTestCase {
+
+		@Configuration
+		static class Config {
+		}
+	}
+
+	@Configuration
+	@Retention(RetentionPolicy.RUNTIME)
+	@Target(ElementType.TYPE)
+	private static @interface MetaConfig {
+	}
+
+	private static class MetaAnnotatedConfigTestCase {
+
+		@MetaConfig
+		static class Config {
+		}
+	}
+
+}