Allow directly present @BootstrapWith to override meta annotations

Prior to this commit, if a test class was meta-annotated with multiple
@BootstrapWith declarations that registered different
TestContextBootstrapper implementations, such a configuration would
result in an IllegalStateException, and there was no way to override
this behavior.

This commit addresses this shortcoming by relaxing the explicit
TestContextBootstrapper resolution in BootstrapUtils so that a directly
present @BootstrapWith annotation will now override declarations of
@BootstrapWith that are meta-present. In other words, if @BootstrapWith
is used as a meta-annotation, it can be overridden directly on the test
class via an explicit, local declaration of @BootstrapWith.

Issue: SPR-17006

Author: sbrannen

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

@@ -26,7 +26,6 @@
 import org.springframework.core.annotation.AnnotatedElementUtils;
 import org.springframework.core.annotation.AnnotationAttributes;
 import org.springframework.lang.Nullable;
-import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 
 /**
@@ -154,10 +153,19 @@ private static Class<?> resolveExplicitTestContextBootstrapper(Class<?> testClas
 		if (annotations.isEmpty()) {
 			return null;
 		}
-		Assert.state(annotations.size() <= 1, () -> String.format(
+		if (annotations.size() == 1) {
+			return annotations.iterator().next().value();
+		}
+
+		// Allow directly-present annotation to override annotations that are meta-present.
+		BootstrapWith bootstrapWith = testClass.getDeclaredAnnotation(BootstrapWith.class);
+		if (bootstrapWith != null) {
+			return bootstrapWith.value();
+		}
+
+		throw new IllegalStateException(String.format(
 				"Configuration error: found multiple declarations of @BootstrapWith for test class [%s]: %s",
 				testClass.getName(), annotations));
-		return annotations.iterator().next().value();
 	}
 
 	private static Class<?> resolveDefaultTestContextBootstrapper(Class<?> testClass) throws Exception {

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

@@ -99,6 +99,14 @@ public void resolveTestContextBootstrapperWithDuplicatingMetaBootstrapWithAnnota
 		assertBootstrapper(DuplicateMetaAnnotatedBootstrapWithAnnotationClass.class, FooBootstrapper.class);
 	}
 
+	/**
+	 * @since 5.1
+	 */
+	@Test
+	public void resolveTestContextBootstrapperWithLocalDeclarationThatOverridesMetaBootstrapWithAnnotations() {
+		assertBootstrapper(LocalDeclarationAndMetaAnnotatedBootstrapWithAnnotationClass.class, EnigmaBootstrapper.class);
+	}
+
 	private void assertBootstrapper(Class<?> testClass, Class<?> expectedBootstrapper) {
 		BootstrapContext bootstrapContext = BootstrapTestUtils.buildBootstrapContext(testClass, delegate);
 		TestContextBootstrapper bootstrapper = resolveTestContextBootstrapper(bootstrapContext);
@@ -112,6 +120,8 @@ static class FooBootstrapper extends DefaultTestContextBootstrapper {}
 
 	static class BarBootstrapper extends DefaultTestContextBootstrapper {}
 
+	static class EnigmaBootstrapper extends DefaultTestContextBootstrapper {}
+
 	@BootstrapWith(FooBootstrapper.class)
 	@Retention(RetentionPolicy.RUNTIME)
 	@interface BootWithFoo {}
@@ -146,7 +156,12 @@ static class MetaAnnotatedBootstrapWithAnnotationClass {}
 	@BootWithFoo
 	@BootWithFooAgain
 	static class DuplicateMetaAnnotatedBootstrapWithAnnotationClass {}
-
+	
+	@BootWithFoo
+	@BootWithBar
+	@BootstrapWith(EnigmaBootstrapper.class)
+	static class LocalDeclarationAndMetaAnnotatedBootstrapWithAnnotationClass {}
+	
 	@WebAppConfiguration
 	static class WebAppConfigurationAnnotatedClass {}