[SPR-8387] Fleshing out unit tests for DelegatingSmartContextLoader.

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

@@ -49,8 +49,8 @@ import org.springframework.util.StringUtils;
  */
 public class MergedContextConfiguration {
 
-	private static final String[] EMPTY_STRING_ARRAY = new String[] {};
+	private static final String[] EMPTY_STRING_ARRAY = new String[0];
-	private static final Class<?>[] EMPTY_CLASS_ARRAY = new Class<?>[] {};
+	private static final Class<?>[] EMPTY_CLASS_ARRAY = new Class<?>[0];
 
 	private final Class<?> testClass;
 
@@ -85,6 +85,13 @@ public class MergedContextConfiguration {
 		return StringUtils.toStringArray(sortedProfilesSet);
 	}
 
+	/**
+	 * Generate a null-safe {@link String} representation of the supplied {@link ContextLoader}.
+	 */
+	private static String nullSafeToString(ContextLoader contextLoader) {
+		return contextLoader == null ? "null" : contextLoader.getClass().getName();
+	}
+
 	/**
 	 * Generate a context <em>key</em> from the supplied values.
 	 */
@@ -94,7 +101,7 @@ public class MergedContextConfiguration {
 		String locationsKey = ObjectUtils.nullSafeToString(locations);
 		String classesKey = ObjectUtils.nullSafeToString(classes);
 		String activeProfilesKey = ObjectUtils.nullSafeToString(activeProfiles);
-		String contextLoaderKey = contextLoader == null ? "null" : contextLoader.getClass().getName();
+		String contextLoaderKey = nullSafeToString(contextLoader);
 
 		return String.format("locations = %s, classes = %s, activeProfiles = %s, contextLoader = %s", locationsKey,
 			classesKey, activeProfilesKey, contextLoaderKey);
@@ -187,7 +194,7 @@ public class MergedContextConfiguration {
 		.append("locations", ObjectUtils.nullSafeToString(this.locations))//
 		.append("classes", ObjectUtils.nullSafeToString(this.classes))//
 		.append("activeProfiles", ObjectUtils.nullSafeToString(this.activeProfiles))//
-		.append("contextLoader", this.contextLoader)//
+		.append("contextLoader", nullSafeToString(contextLoader))//
 		.append("contextKey", this.contextKey)//
 		.toString();
 	}

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

@@ -95,7 +95,7 @@ public abstract class AbstractContextLoader implements SmartContextLoader {
 	 * TODO Document default supports(MergedContextConfiguration) implementation.
 	 */
 	public boolean supports(MergedContextConfiguration mergedConfig) {
-		return !ObjectUtils.isEmpty(mergedConfig.getLocations());
+		return !ObjectUtils.isEmpty(mergedConfig.getLocations()) && ObjectUtils.isEmpty(mergedConfig.getClasses());
 	}
 
 	// --- ContextLoader -------------------------------------------------------

org.springframework.test/src/main/java/org/springframework/test/context/support/DelegatingSmartContextLoader.java

@@ -119,20 +119,20 @@ public class DelegatingSmartContextLoader implements SmartContextLoader {
 	public ApplicationContext loadContext(MergedContextConfiguration mergedConfig) throws Exception {
 
 		for (SmartContextLoader loader : candidates) {
-			if (logger.isDebugEnabled()) {
-				logger.debug(String.format("Delegating to %s to load context from [%s].", loader.getClass().getName(),
-					mergedConfig));
-			}
 
 			// Ask each loader if it can load a context from the mergedConfig.
 			// If a loader can, let it; otherwise, continue iterating over all
 			// remaining candidates.
 			if (loader.supports(mergedConfig)) {
+				if (logger.isDebugEnabled()) {
+					logger.debug(String.format("Delegating to %s to load context from [%s].",
+						loader.getClass().getName(), mergedConfig));
+				}
 				return loader.loadContext(mergedConfig);
 			}
 		}
 
-		throw new IllegalStateException(String.format("None of the candidate SmartContextLoaders %s "
+		throw new IllegalStateException(String.format("None of the SmartContextLoader candidates %s "
 				+ "was able to load an ApplicationContext from [%s].", candidates, mergedConfig));
 	}
 

org.springframework.test/src/test/java/org/springframework/test/context/support/DelegatingSmartContextLoaderTests.java

@@ -16,7 +16,11 @@
 
 package org.springframework.test.context.support;
 
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import org.junit.Test;
+import org.springframework.test.context.MergedContextConfiguration;
 
 /**
  * Unit tests for {@link DelegatingSmartContextLoader}.
@@ -26,14 +30,17 @@ import org.junit.Test;
  */
 public class DelegatingSmartContextLoaderTests {
 
-	private DelegatingSmartContextLoader loader = new DelegatingSmartContextLoader();
+	private static final Class<?>[] EMPTY_CLASS_ARRAY = new Class<?>[0];
+	private static final String[] EMPTY_STRING_ARRAY = new String[0];
+
+	private final DelegatingSmartContextLoader loader = new DelegatingSmartContextLoader();
 
 
 	// --- SmartContextLoader --------------------------------------------------
 
 	@Test
 	public void generatesDefaults() {
-		// TODO test generateDefaults().
+		assertTrue(loader.generatesDefaults());
 	}
 
 	@Test
@@ -42,8 +49,31 @@ public class DelegatingSmartContextLoaderTests {
 	}
 
 	@Test
-	public void supports() {
+	public void doesNotSupportEmptyConfig() {
-		// TODO test supports().
+		MergedContextConfiguration mergedConfig = new MergedContextConfiguration(getClass(), EMPTY_STRING_ARRAY,
+			EMPTY_CLASS_ARRAY, EMPTY_STRING_ARRAY, loader);
+		assertFalse(loader.supports(mergedConfig));
+	}
+
+	@Test
+	public void doesNotSupportLocationsAndConfigurationClasses() {
+		MergedContextConfiguration mergedConfig = new MergedContextConfiguration(getClass(),
+			new String[] { "foo.xml" }, new Class<?>[] { getClass() }, EMPTY_STRING_ARRAY, loader);
+		assertFalse(loader.supports(mergedConfig));
+	}
+
+	@Test
+	public void supportsLocations() {
+		MergedContextConfiguration mergedConfig = new MergedContextConfiguration(getClass(),
+			new String[] { "foo.xml" }, EMPTY_CLASS_ARRAY, EMPTY_STRING_ARRAY, loader);
+		assertTrue(loader.supports(mergedConfig));
+	}
+
+	@Test
+	public void supportsConfigurationClasses() {
+		MergedContextConfiguration mergedConfig = new MergedContextConfiguration(getClass(), EMPTY_STRING_ARRAY,
+			new Class<?>[] { getClass() }, EMPTY_STRING_ARRAY, loader);
+		assertTrue(loader.supports(mergedConfig));
 	}
 
 	@Test
@@ -55,12 +85,12 @@ public class DelegatingSmartContextLoaderTests {
 
 	@Test(expected = UnsupportedOperationException.class)
 	public void processLocations() {
-		loader.processLocations(getClass(), new String[0]);
+		loader.processLocations(getClass(), EMPTY_STRING_ARRAY);
 	}
 
 	@Test(expected = UnsupportedOperationException.class)
 	public void loadContextFromLocations() throws Exception {
-		loader.loadContext(new String[0]);
+		loader.loadContext(EMPTY_STRING_ARRAY);
 	}
 
 }