Merge pull request #991 from philwebb/SPR-13998

* SPR-13998:
  Polish ContextCustomizer support in the TCF
  Introduce ContextCustomizer API in the TestContext Framework

spring-test/src/main/java/org/springframework/test/context/ContextCustomizer.java

@@ -0,0 +1,49 @@
+/*
+ * 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.test.context;
+
+import org.springframework.context.ConfigurableApplicationContext;
+
+/**
+ * Strategy interface for customizing {@link ConfigurableApplicationContext
+ * application contexts} that are created and managed by the <em>Spring
+ * TestContext Framework</em>.
+ *
+ * <p>Customizers are created by {@link ContextCustomizerFactory} implementations.
+ *
+ * <p>Implementations must implement correct {@code equals} and {@code hashCode}
+ * methods since customizers form part of the {@link MergedContextConfiguration}
+ * which is used as a cache key.
+ *
+ * @author Phillip Webb
+ * @author Sam Brannen
+ * @since 4.3
+ * @see ContextCustomizerFactory
+ * @see org.springframework.test.context.support.AbstractContextLoader#customizeContext
+ */
+public interface ContextCustomizer {
+
+	/**
+	 * Customize the supplied {@code ConfigurableApplicationContext} <em>after</em>
+	 * bean definitions have been loaded into the context but <em>before</em> the
+	 * context has been refreshed.
+	 * @param context the context to customize
+	 * @param mergedConfig the merged context configuration
+	 */
+	void customizeContext(ConfigurableApplicationContext context, MergedContextConfiguration mergedConfig);
+
+}

spring-test/src/main/java/org/springframework/test/context/ContextCustomizerFactory.java

@@ -0,0 +1,52 @@
+/*
+ * 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.test.context;
+
+import java.util.List;
+
+/**
+ * Factory for creating {@link ContextCustomizer ContextCustomizers}.
+ *
+ * <p>Factories are invoked after {@link ContextLoader ContextLoaders} have
+ * processed context configuration attributes but before the
+ * {@link MergedContextConfiguration} is created.
+ *
+ * <p>By default, the Spring TestContext Framework will use the
+ * {@link org.springframework.core.io.support.SpringFactoriesLoader SpringFactoriesLoader}
+ * mechanism for loading factories configured in all {@code META-INF/spring.factories}
+ * files on the classpath.
+ *
+ * @author Phillip Webb
+ * @author Sam Brannen
+ * @since 4.3
+ */
+public interface ContextCustomizerFactory {
+
+	/**
+	 * Create a {@link ContextCustomizer} that should be used to customize a
+	 * {@link org.springframework.context.ConfigurableApplicationContext ConfigurableApplicationContext}
+	 * before it is refreshed.
+	 * @param testClass the test class
+	 * @param configAttributes the list of context configuration attributes for
+	 * the test class, ordered <em>bottom-up</em> (i.e., as if we were traversing
+	 * up the class hierarchy); never {@code null} or empty
+	 * @return a {@link ContextCustomizer} or {@code null} if no customizer should
+	 * be used
+	 */
+	ContextCustomizer createContextCustomizer(Class<?> testClass, List<ContextConfigurationAttributes> configAttributes);
+
+}

spring-test/src/main/java/org/springframework/test/context/MergedContextConfiguration.java

@@ -55,6 +55,7 @@ import org.springframework.util.StringUtils;
  * that was loaded using properties of this {@code MergedContextConfiguration}.
  *
  * @author Sam Brannen
+ * @author Phillip Webb
  * @since 3.1
  * @see ContextConfiguration
  * @see ContextHierarchy
@@ -74,6 +75,8 @@ public class MergedContextConfiguration implements Serializable {
 	private static final Set<Class<? extends ApplicationContextInitializer<? extends ConfigurableApplicationContext>>> EMPTY_INITIALIZER_CLASSES =
 			Collections.<Class<? extends ApplicationContextInitializer<? extends ConfigurableApplicationContext>>> emptySet();
 
+	private static final Set<ContextCustomizer> EMPTY_CONTEXT_CUSTOMIZERS = Collections.<ContextCustomizer> emptySet();
+
 
 	private final Class<?> testClass;
 
@@ -89,6 +92,8 @@ public class MergedContextConfiguration implements Serializable {
 
 	private final String[] propertySourceProperties;
 
+	private final Set<ContextCustomizer> contextCustomizers;
+
 	private final ContextLoader contextLoader;
 
 	private final CacheAwareContextLoaderDelegate cacheAwareContextLoaderDelegate;
@@ -111,6 +116,11 @@ public class MergedContextConfiguration implements Serializable {
 				Collections.unmodifiableSet(contextInitializerClasses) : EMPTY_INITIALIZER_CLASSES);
 	}
 
+	private static Set<ContextCustomizer> processContextCustomizers(Set<ContextCustomizer> contextCustomizers) {
+		return (contextCustomizers != null ?
+				Collections.unmodifiableSet(contextCustomizers) : EMPTY_CONTEXT_CUSTOMIZERS);
+	}
+
 	private static String[] processActiveProfiles(String[] activeProfiles) {
 		if (activeProfiles == null) {
 			return EMPTY_STRING_ARRAY;
@@ -201,8 +211,8 @@ public class MergedContextConfiguration implements Serializable {
 	public MergedContextConfiguration(MergedContextConfiguration mergedConfig) {
 		this(mergedConfig.testClass, mergedConfig.locations, mergedConfig.classes,
 			mergedConfig.contextInitializerClasses, mergedConfig.activeProfiles, mergedConfig.propertySourceLocations,
-			mergedConfig.propertySourceProperties, mergedConfig.contextLoader,
-			mergedConfig.cacheAwareContextLoaderDelegate, mergedConfig.parent);
+			mergedConfig.propertySourceProperties, mergedConfig.contextCustomizers,
+			mergedConfig.contextLoader, mergedConfig.cacheAwareContextLoaderDelegate, mergedConfig.parent);
 	}
 
 	/**
@@ -233,6 +243,41 @@ public class MergedContextConfiguration implements Serializable {
 			String[] activeProfiles, String[] propertySourceLocations, String[] propertySourceProperties,
 			ContextLoader contextLoader, CacheAwareContextLoaderDelegate cacheAwareContextLoaderDelegate,
 			MergedContextConfiguration parent) {
+		this(testClass, locations, classes, contextInitializerClasses, activeProfiles,
+				propertySourceLocations, propertySourceProperties,
+				Collections.<ContextCustomizer> emptySet(), contextLoader,
+				cacheAwareContextLoaderDelegate, parent);
+	}
+
+	/**
+	 * Create a new {@code MergedContextConfiguration} instance for the
+	 * supplied parameters.
+	 * <p>If a {@code null} value is supplied for {@code locations},
+	 * {@code classes}, {@code activeProfiles}, {@code propertySourceLocations},
+	 * or {@code propertySourceProperties} an empty array will be stored instead.
+	 * If a {@code null} value is supplied for {@code contextInitializerClasses}
+	 * or {@code contextCustomizers}, an empty set will be stored instead.
+	 * Furthermore, active profiles will be sorted, and duplicate profiles
+	 * will be removed.
+	 * @param testClass the test class for which the configuration was merged
+	 * @param locations the merged context resource locations
+	 * @param classes the merged annotated classes
+	 * @param contextInitializerClasses the merged context initializer classes
+	 * @param activeProfiles the merged active bean definition profiles
+	 * @param propertySourceLocations the merged {@code PropertySource} locations
+	 * @param propertySourceProperties the merged {@code PropertySource} properties
+	 * @param contextCustomizers the context customizers
+	 * @param contextLoader the resolved {@code ContextLoader}
+	 * @param cacheAwareContextLoaderDelegate a cache-aware context loader
+	 * delegate with which to retrieve the parent context
+	 * @param parent the parent configuration or {@code null} if there is no parent
+	 * @since 4.3
+	 */
+	public MergedContextConfiguration(Class<?> testClass, String[] locations, Class<?>[] classes,
+			Set<Class<? extends ApplicationContextInitializer<? extends ConfigurableApplicationContext>>> contextInitializerClasses,
+			String[] activeProfiles, String[] propertySourceLocations, String[] propertySourceProperties,
+			Set<ContextCustomizer> contextCustomizers, ContextLoader contextLoader,
+			CacheAwareContextLoaderDelegate cacheAwareContextLoaderDelegate, MergedContextConfiguration parent) {
 
 		this.testClass = testClass;
 		this.locations = processStrings(locations);
@@ -241,6 +286,7 @@ public class MergedContextConfiguration implements Serializable {
 		this.activeProfiles = processActiveProfiles(activeProfiles);
 		this.propertySourceLocations = processStrings(propertySourceLocations);
 		this.propertySourceProperties = processStrings(propertySourceProperties);
+		this.contextCustomizers = processContextCustomizers(contextCustomizers);
 		this.contextLoader = contextLoader;
 		this.cacheAwareContextLoaderDelegate = cacheAwareContextLoaderDelegate;
 		this.parent = parent;
@@ -348,6 +394,14 @@ public class MergedContextConfiguration implements Serializable {
 		return this.propertySourceProperties;
 	}
 
+	/**
+	 * Get the merged {@link ContextCustomizer ContextCustomizers} that will be applied
+	 * when the application context is loaded.
+	 */
+	public Set<ContextCustomizer> getContextCustomizers() {
+		return this.contextCustomizers;
+	}
+
 	/**
 	 * Get the resolved {@link ContextLoader} for the {@linkplain #getTestClass() test class}.
 	 */
@@ -424,6 +478,9 @@ public class MergedContextConfiguration implements Serializable {
 		if (!Arrays.equals(this.propertySourceProperties, otherConfig.propertySourceProperties)) {
 			return false;
 		}
+		if (!this.contextCustomizers.equals(otherConfig.contextCustomizers)) {
+			return false;
+		}
 
 		if (this.parent == null) {
 			if (otherConfig.parent != null) {
@@ -454,6 +511,7 @@ public class MergedContextConfiguration implements Serializable {
 		result = 31 * result + Arrays.hashCode(this.activeProfiles);
 		result = 31 * result + Arrays.hashCode(this.propertySourceLocations);
 		result = 31 * result + Arrays.hashCode(this.propertySourceProperties);
+		result = 31 * result + this.contextCustomizers.hashCode();
 		result = 31 * result + (this.parent != null ? this.parent.hashCode() : 0);
 		result = 31 * result + nullSafeToString(this.contextLoader).hashCode();
 		return result;
@@ -466,6 +524,7 @@ public class MergedContextConfiguration implements Serializable {
 	 * {@linkplain #getActiveProfiles() active profiles},
 	 * {@linkplain #getPropertySourceLocations() property source locations},
 	 * {@linkplain #getPropertySourceProperties() property source properties},
+	 * {@linkplain #getContextCustomizers() context customizers},
 	 * the name of the {@link #getContextLoader() ContextLoader}, and the
 	 * {@linkplain #getParent() parent configuration}.
 	 */
@@ -479,6 +538,7 @@ public class MergedContextConfiguration implements Serializable {
 				.append("activeProfiles", ObjectUtils.nullSafeToString(this.activeProfiles))
 				.append("propertySourceLocations", ObjectUtils.nullSafeToString(this.propertySourceLocations))
 				.append("propertySourceProperties", ObjectUtils.nullSafeToString(this.propertySourceProperties))
+				.append("contextCustomizers", this.contextCustomizers)
 				.append("contextLoader", nullSafeToString(this.contextLoader))
 				.append("parent", this.parent)
 				.toString();

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

@@ -33,6 +33,7 @@ import org.springframework.core.annotation.AnnotationAwareOrderComparator;
 import org.springframework.core.env.PropertySource;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.test.context.ContextConfigurationAttributes;
+import org.springframework.test.context.ContextCustomizer;
 import org.springframework.test.context.ContextLoader;
 import org.springframework.test.context.MergedContextConfiguration;
 import org.springframework.test.context.SmartContextLoader;
@@ -56,10 +57,13 @@ import org.springframework.util.ResourceUtils;
  *
  * @author Sam Brannen
  * @author Juergen Hoeller
+ * @author Phillip Webb
  * @since 2.5
  * @see #generateDefaultLocations
  * @see #getResourceSuffixes
  * @see #modifyLocations
+ * @see #prepareContext
+ * @see #customizeContext
  */
 public abstract class AbstractContextLoader implements SmartContextLoader {
 
@@ -167,6 +171,23 @@ public abstract class AbstractContextLoader implements SmartContextLoader {
 		}
 	}
 
+	/**
+	 * Customize the {@link ConfigurableApplicationContext} created by this
+	 * {@code ContextLoader} <em>after</em> bean definitions have been loaded
+	 * into the context but <em>before</em> the context has been refreshed.
+	 * <p>The default implementation delegates to all
+	 * {@link MergedContextConfiguration#getContextCustomizers context customizers}
+	 * that have been registered with the supplied {@code mergedConfig}.
+	 * @param context the newly created application context
+	 * @param mergedConfig the merged context configuration
+	 * @since 4.3
+	 */
+	protected void customizeContext(ConfigurableApplicationContext context, MergedContextConfiguration mergedConfig) {
+		for (ContextCustomizer contextCustomizer : mergedConfig.getContextCustomizers()) {
+			contextCustomizer.customizeContext(context, mergedConfig);
+		}
+	}
+
 
 	// --- ContextLoader -------------------------------------------------------
 

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

@@ -253,8 +253,9 @@ public abstract class AbstractDelegatingSmartContextLoader implements SmartConte
 		}
 
 		// If neither of the candidates supports the mergedConfig based on resources but
-		// ACIs were declared, then delegate to the annotation config loader.
-		if (!mergedConfig.getContextInitializerClasses().isEmpty()) {
+		// ACIs or customizers were declared, then delegate to the annotation config
+		// loader.
+		if (!mergedConfig.getContextInitializerClasses().isEmpty() || !mergedConfig.getContextCustomizers().isEmpty()) {
 			return delegateLoading(getAnnotationConfigLoader(), mergedConfig);
 		}
 

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

@@ -16,7 +16,6 @@
 
 package org.springframework.test.context.support;
 
-
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
@@ -53,6 +52,7 @@ import org.springframework.util.StringUtils;
  *
  * @author Sam Brannen
  * @author Juergen Hoeller
+ * @author Phillip Webb
  * @since 2.5
  * @see #loadContext(MergedContextConfiguration)
  * @see #loadContext(String...)
@@ -92,6 +92,8 @@ public abstract class AbstractGenericContextLoader extends AbstractContextLoader
 	 * annotation configuration processors.</li>
 	 * <li>Calls {@link #customizeContext(GenericApplicationContext)} to allow for customizing the context
 	 * before it is refreshed.</li>
+	 * <li>Calls {@link #customizeContext(ConfigurableApplicationContext, MergedContextConfiguration)} to
+	 * allow for customizing the context before it is refreshed.</li>
 	 * <li>{@link ConfigurableApplicationContext#refresh Refreshes} the
 	 * context and registers a JVM shutdown hook for it.</li>
 	 * </ul>
@@ -122,6 +124,7 @@ public abstract class AbstractGenericContextLoader extends AbstractContextLoader
 		loadBeanDefinitions(context, mergedConfig);
 		AnnotationConfigUtils.registerAnnotationConfigProcessors(context);
 		customizeContext(context);
+		customizeContext(context, mergedConfig);
 		context.refresh();
 		context.registerShutdownHook();
 		return context;
@@ -205,6 +208,7 @@ public abstract class AbstractGenericContextLoader extends AbstractContextLoader
 	 * @see GenericApplicationContext#setAllowBeanDefinitionOverriding
 	 * @see GenericApplicationContext#setResourceLoader
 	 * @see GenericApplicationContext#setId
+	 * @see #prepareContext(ConfigurableApplicationContext, MergedContextConfiguration)
 	 * @since 2.5
 	 */
 	protected void prepareContext(GenericApplicationContext context) {
@@ -278,6 +282,7 @@ public abstract class AbstractGenericContextLoader extends AbstractContextLoader
 	 * @param context the newly created application context
 	 * @see #loadContext(MergedContextConfiguration)
 	 * @see #loadContext(String...)
+	 * @see #customizeContext(ConfigurableApplicationContext, MergedContextConfiguration)
 	 * @since 2.5
 	 */
 	protected void customizeContext(GenericApplicationContext context) {

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

@@ -38,6 +38,8 @@ import org.springframework.test.context.BootstrapContext;
 import org.springframework.test.context.CacheAwareContextLoaderDelegate;
 import org.springframework.test.context.ContextConfiguration;
 import org.springframework.test.context.ContextConfigurationAttributes;
+import org.springframework.test.context.ContextCustomizer;
+import org.springframework.test.context.ContextCustomizerFactory;
 import org.springframework.test.context.ContextHierarchy;
 import org.springframework.test.context.ContextLoader;
 import org.springframework.test.context.MergedContextConfiguration;
@@ -385,10 +387,13 @@ public abstract class AbstractTestContextBootstrapper implements TestContextBoot
 			}
 		}
 
-		if (requireLocationsClassesOrInitializers && areAllEmpty(locations, classes, initializers)) {
+		Set<ContextCustomizer> contextCustomizers = getContextCustomizers(testClass,
+				Collections.unmodifiableList(configAttributesList));
+
+		if (requireLocationsClassesOrInitializers && areAllEmpty(locations, classes, initializers, contextCustomizers)) {
 			throw new IllegalStateException(String.format(
 					"%s was unable to detect defaults, and no ApplicationContextInitializers "
-							+ "were declared for context configuration attributes %s",
+							+ "or ContextCustomizers were declared for context configuration attributes %s",
 					contextLoader.getClass().getSimpleName(), configAttributesList));
 		}
 
@@ -400,11 +405,40 @@ public abstract class AbstractTestContextBootstrapper implements TestContextBoot
 				ActiveProfilesUtils.resolveActiveProfiles(testClass),
 				mergedTestPropertySources.getLocations(),
 				mergedTestPropertySources.getProperties(),
-				contextLoader, cacheAwareContextLoaderDelegate, parentConfig);
+				contextCustomizers, contextLoader, cacheAwareContextLoaderDelegate, parentConfig);
 
 		return processMergedContextConfiguration(mergedConfig);
 	}
 
+	/**
+	 * @since 4.3
+	 */
+	private Set<ContextCustomizer> getContextCustomizers(Class<?> testClass,
+			List<ContextConfigurationAttributes> configAttributes) {
+
+		List<ContextCustomizerFactory> factories = getContextCustomizerFactories();
+		Set<ContextCustomizer> customizers = new LinkedHashSet<ContextCustomizer>(factories.size());
+		for (ContextCustomizerFactory factory : factories) {
+			ContextCustomizer customizer = factory.createContextCustomizer(testClass, configAttributes);
+			if (customizer != null) {
+				customizers.add(customizer);
+			}
+		}
+		return customizers;
+	}
+
+	/**
+	 * Get the {@link ContextCustomizerFactory} instances for this bootstrapper.
+	 * <p>The default implementation uses the {@link SpringFactoriesLoader} mechanism
+	 * for loading factories configured in all {@code META-INF/spring.factories}
+	 * files on the classpath.
+	 * @since 4.3
+	 * @see SpringFactoriesLoader#loadFactories
+	 */
+	protected List<ContextCustomizerFactory> getContextCustomizerFactories() {
+		return SpringFactoriesLoader.loadFactories(ContextCustomizerFactory.class, getClass().getClassLoader());
+	}
+
 	/**
 	 * @since 4.3
 	 */

spring-test/src/main/java/org/springframework/test/context/web/AbstractGenericWebContextLoader.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * 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.
@@ -53,6 +53,7 @@ import org.springframework.web.context.support.GenericWebApplicationContext;
  * {@link #loadBeanDefinitions}.
  *
  * @author Sam Brannen
+ * @author Phillip Webb
  * @since 3.2
  * @see #loadContext(MergedContextConfiguration)
  * @see #loadContext(String...)
@@ -256,15 +257,17 @@ public abstract class AbstractGenericWebContextLoader extends AbstractContextLoa
 	 * loader <i>after</i> bean definitions have been loaded into the context but
 	 * <i>before</i> the context is refreshed.
 	 *
-	 * <p>The default implementation is empty but can be overridden in subclasses
-	 * to customize the web application context.
+	 * <p>The default implementation simply delegates to
+	 * {@link AbstractContextLoader#customizeContext(ConfigurableApplicationContext, MergedContextConfiguration)}.
 	 *
 	 * @param context the newly created web application context
 	 * @param webMergedConfig the merged context configuration to use to load the
 	 * web application context
 	 * @see #loadContext(MergedContextConfiguration)
+	 * @see #customizeContext(ConfigurableApplicationContext, MergedContextConfiguration)
 	 */
 	protected void customizeContext(GenericWebApplicationContext context, WebMergedContextConfiguration webMergedConfig) {
+		super.customizeContext(context, webMergedConfig);
 	}
 
 	// --- ContextLoader -------------------------------------------------------

spring-test/src/main/java/org/springframework/test/context/web/WebMergedContextConfiguration.java

@@ -22,6 +22,7 @@ import org.springframework.context.ApplicationContextInitializer;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.core.style.ToStringCreator;
 import org.springframework.test.context.CacheAwareContextLoaderDelegate;
+import org.springframework.test.context.ContextCustomizer;
 import org.springframework.test.context.ContextLoader;
 import org.springframework.test.context.MergedContextConfiguration;
 import org.springframework.util.ObjectUtils;
@@ -132,13 +133,48 @@ public class WebMergedContextConfiguration extends MergedContextConfiguration {
 			String resourceBasePath, ContextLoader contextLoader,
 			CacheAwareContextLoaderDelegate cacheAwareContextLoaderDelegate, MergedContextConfiguration parent) {
 
+		this(testClass, locations, classes, contextInitializerClasses, activeProfiles, propertySourceLocations,
+			propertySourceProperties, null, resourceBasePath, contextLoader, cacheAwareContextLoaderDelegate, parent);
+	}
+
+	/**
+	 * Create a new {@code WebMergedContextConfiguration} instance for the
+	 * supplied parameters.
+	 * <p>If a {@code null} value is supplied for {@code locations},
+	 * {@code classes}, {@code activeProfiles}, {@code propertySourceLocations},
+	 * or {@code propertySourceProperties} an empty array will be stored instead.
+	 * If a {@code null} value is supplied for {@code contextInitializerClasses}
+	 * or {@code contextCustomizers}, an empty set will be stored instead.
+	 * If an <em>empty</em> value is supplied for the {@code resourceBasePath}
+	 * an empty string will be used. Furthermore, active profiles will be sorted,
+	 * and duplicate profiles will be removed.
+	 * @param testClass the test class for which the configuration was merged
+	 * @param locations the merged context resource locations
+	 * @param classes the merged annotated classes
+	 * @param contextInitializerClasses the merged context initializer classes
+	 * @param activeProfiles the merged active bean definition profiles
+	 * @param propertySourceLocations the merged {@code PropertySource} locations
+	 * @param propertySourceProperties the merged {@code PropertySource} properties
+	 * @param contextCustomizers the context customizers
+	 * @param resourceBasePath the resource path to the root directory of the web application
+	 * @param contextLoader the resolved {@code ContextLoader}
+	 * @param cacheAwareContextLoaderDelegate a cache-aware context loader
+	 * delegate with which to retrieve the parent context
+	 * @param parent the parent configuration or {@code null} if there is no parent
+	 * @since 4.3
+	 */
+	public WebMergedContextConfiguration(Class<?> testClass, String[] locations, Class<?>[] classes,
+			Set<Class<? extends ApplicationContextInitializer<? extends ConfigurableApplicationContext>>> contextInitializerClasses,
+			String[] activeProfiles, String[] propertySourceLocations, String[] propertySourceProperties,
+			Set<ContextCustomizer> contextCustomizers, String resourceBasePath, ContextLoader contextLoader,
+			CacheAwareContextLoaderDelegate cacheAwareContextLoaderDelegate, MergedContextConfiguration parent) {
+
 		super(testClass, locations, classes, contextInitializerClasses, activeProfiles, propertySourceLocations,
-			propertySourceProperties, contextLoader, cacheAwareContextLoaderDelegate, parent);
+			propertySourceProperties, contextCustomizers, contextLoader, cacheAwareContextLoaderDelegate, parent);
 
-		this.resourceBasePath = !StringUtils.hasText(resourceBasePath) ? "" : resourceBasePath;
+		this.resourceBasePath = (StringUtils.hasText(resourceBasePath) ? resourceBasePath : "");
 	}
 
-
 	/**
 	 * Get the resource path to the root directory of the web application for the
 	 * {@linkplain #getTestClass() test class}, configured via {@code @WebAppConfiguration}.
@@ -182,6 +218,7 @@ public class WebMergedContextConfiguration extends MergedContextConfiguration {
 	 * {@linkplain #getActiveProfiles() active profiles},
 	 * {@linkplain #getPropertySourceLocations() property source locations},
 	 * {@linkplain #getPropertySourceProperties() property source properties},
+	 * {@linkplain #getContextCustomizers() context customizers},
 	 * {@linkplain #getResourceBasePath() resource base path}, the name of the
 	 * {@link #getContextLoader() ContextLoader}, and the
 	 * {@linkplain #getParent() parent configuration}.
@@ -196,6 +233,7 @@ public class WebMergedContextConfiguration extends MergedContextConfiguration {
 				.append("activeProfiles", ObjectUtils.nullSafeToString(getActiveProfiles()))
 				.append("propertySourceLocations", ObjectUtils.nullSafeToString(getPropertySourceLocations()))
 				.append("propertySourceProperties", ObjectUtils.nullSafeToString(getPropertySourceProperties()))
+				.append("contextCustomizers", getContextCustomizers())
 				.append("resourceBasePath", getResourceBasePath())
 				.append("contextLoader", nullSafeToString(getContextLoader()))
 				.append("parent", getParent())

spring-test/src/test/java/org/springframework/test/context/MergedContextConfigurationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * 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.
@@ -16,6 +16,7 @@
 
 package org.springframework.test.context;
 
+import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;
 
@@ -28,6 +29,7 @@ import org.springframework.test.context.support.AnnotationConfigContextLoader;
 import org.springframework.test.context.support.GenericXmlContextLoader;
 
 import static org.junit.Assert.*;
+import static org.mockito.Mockito.*;
 
 /**
  * Unit tests for {@link MergedContextConfiguration}.
@@ -37,6 +39,7 @@ import static org.junit.Assert.*;
  * {@link org.springframework.test.context.cache.ContextCache ContextCache}.
  *
  * @author Sam Brannen
+ * @author Phillip Webb
  * @since 3.1
  */
 public class MergedContextConfigurationTests {
@@ -400,6 +403,35 @@ public class MergedContextConfigurationTests {
 		assertNotEquals(mergedConfig2, mergedConfig1);
 	}
 
+	/**
+	 * @since 4.3
+	 */
+	@Test
+	public void equalsWithSameContextCustomizers() {
+		Set<ContextCustomizer> customizers = Collections.singleton(mock(ContextCustomizer.class));
+		MergedContextConfiguration mergedConfig1 = new MergedContextConfiguration(getClass(), EMPTY_STRING_ARRAY,
+			EMPTY_CLASS_ARRAY, null, EMPTY_STRING_ARRAY, null, null, customizers, loader, null, null);
+		MergedContextConfiguration mergedConfig2 = new MergedContextConfiguration(getClass(), EMPTY_STRING_ARRAY,
+			EMPTY_CLASS_ARRAY, null, EMPTY_STRING_ARRAY, null, null, customizers, loader, null, null);
+		assertEquals(mergedConfig1, mergedConfig2);
+	}
+
+	/**
+	 * @since 4.3
+	 */
+	@Test
+	public void equalsWithDifferentContextCustomizers() {
+		Set<ContextCustomizer> customizers1 = Collections.singleton(mock(ContextCustomizer.class));
+		Set<ContextCustomizer> customizers2 = Collections.singleton(mock(ContextCustomizer.class));
+
+		MergedContextConfiguration mergedConfig1 = new MergedContextConfiguration(getClass(), EMPTY_STRING_ARRAY,
+			EMPTY_CLASS_ARRAY, null, EMPTY_STRING_ARRAY, null, null, customizers1, loader, null, null);
+		MergedContextConfiguration mergedConfig2 = new MergedContextConfiguration(getClass(), EMPTY_STRING_ARRAY,
+			EMPTY_CLASS_ARRAY, null, EMPTY_STRING_ARRAY, null, null, customizers2, loader, null, null);
+		assertNotEquals(mergedConfig1, mergedConfig2);
+		assertNotEquals(mergedConfig2, mergedConfig1);
+	}
+
 	/**
 	 * @since 3.2.2
 	 */

spring-test/src/test/java/org/springframework/test/context/junit4/ContextCustomizerSpringRunnerTests.java

@@ -0,0 +1,65 @@
+/*
+ * 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.test.context.junit4;
+
+import java.util.List;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.test.context.BootstrapWith;
+import org.springframework.test.context.ContextCustomizer;
+import org.springframework.test.context.ContextCustomizerFactory;
+import org.springframework.test.context.junit4.ContextCustomizerSpringRunnerTests.CustomTestContextBootstrapper;
+import org.springframework.test.context.support.DefaultTestContextBootstrapper;
+
+import static java.util.Collections.*;
+import static org.junit.Assert.*;
+
+/**
+ * JUnit 4 based integration test which verifies support of
+ * {@link ContextCustomizerFactory} and {@link ContextCustomizer}.
+ *
+ * @author Sam Brannen
+ * @author Phillip Webb
+ * @since 4.3
+ */
+@RunWith(SpringRunner.class)
+@BootstrapWith(CustomTestContextBootstrapper.class)
+public class ContextCustomizerSpringRunnerTests {
+
+	@Autowired String foo;
+
+
+	@Test
+	public void injectedBean() {
+		assertEquals("foo", foo);
+	}
+
+
+	static class CustomTestContextBootstrapper extends DefaultTestContextBootstrapper {
+
+		@Override
+		protected List<ContextCustomizerFactory> getContextCustomizerFactories() {
+			return singletonList((testClass, configAttributes) ->
+				// ContextCustomizer as lambda expression:
+				(context, mergedConfig) -> context.getBeanFactory().registerSingleton("foo", "foo"));
+		}
+	}
+
+}

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

@@ -63,7 +63,7 @@ public class BootstrapTestUtilsMergedConfigTests extends AbstractContextConfigur
 	public void buildMergedConfigWithContextConfigurationWithoutLocationsClassesOrInitializers() {
 		exception.expect(IllegalStateException.class);
 		exception.expectMessage(startsWith("DelegatingSmartContextLoader was unable to detect defaults, "
-				+ "and no ApplicationContextInitializers were declared for context configuration attributes"));
+				+ "and no ApplicationContextInitializers or ContextCustomizers were declared for context configuration attributes"));
 
 		buildMergedContextConfiguration(MissingContextAttributesTestCase.class);
 	}