Do not replace existing Bean Override definition with pseudo-definition

Prior to this commit, BeanOverrideBeanFactoryPostProcessor replaced
existing bean definitions with "pseudo" bean definitions; however, that
is unnecessary. An existing BeanDefinition is suitable as-is and does
not need to be replaced with a pseudo/fake definition.

To address that, this commit reregisters an existing bean definition
and only registers a new bean definition when creating a bean
definition for a nonexistent bean.

As a side effect, we no longer need to copy primary and fallback flags.

Closes gh-33627

Author: sbrannen

spring-test/src/main/java/org/springframework/test/context/bean/override/BeanOverrideBeanFactoryPostProcessor.java

@@ -148,14 +148,17 @@ else if (enforceExistingDefinition) {
 		// Process existing bean definition.
 		if (existingBeanDefinition != null) {
 			validateBeanDefinition(beanFactory, beanName);
-			copyBeanDefinitionProperties(existingBeanDefinition, pseudoBeanDefinition);
+			// Since validation may have registered a singleton as a side effect -- for example,
+			// for a FactoryBean -- we need to remove the bean definition (which removes the
+			// singleton as a side effect) and re-register the bean definition.
 			registry.removeBeanDefinition(beanName);
+			registry.registerBeanDefinition(beanName, existingBeanDefinition);
+		}
+		else {
+			// There was no existing bean definition, so we register the pseudo bean definition
+			// to ensure that a bean definition exists for the given bean name.
+			registry.registerBeanDefinition(beanName, pseudoBeanDefinition);
 		}
-
-		// At this point, we either removed an existing bean definition above, or
-		// there was no bean definition to begin with. So, we register the pseudo bean
-		// definition to ensure that a bean definition exists for the given bean name.
-		registry.registerBeanDefinition(beanName, pseudoBeanDefinition);
 
 		Object override = overrideMetadata.createOverride(beanName, existingBeanDefinition, null);
 		overrideMetadata.track(override, beanFactory);
@@ -294,16 +297,6 @@ private static void validateBeanDefinition(ConfigurableListableBeanFactory beanF
 				() -> "Unable to override bean '" + beanName + "': only singleton beans can be overridden.");
 	}
 
-	/**
-	 * Copy the following properties of the source {@link BeanDefinition} to the
-	 * target: the {@linkplain BeanDefinition#isPrimary() primary flag} and the
-	 * {@linkplain BeanDefinition#isFallback() fallback flag}.
-	 */
-	private static void copyBeanDefinitionProperties(BeanDefinition source, RootBeanDefinition target) {
-		target.setPrimary(source.isPrimary());
-		target.setFallback(source.isFallback());
-	}
-
 
 	static class WrapEarlyBeanPostProcessor implements SmartInstantiationAwareBeanPostProcessor,
 			PriorityOrdered {

spring-test/src/test/java/org/springframework/test/context/bean/override/BeanOverrideBeanFactoryPostProcessorTests.java

@@ -315,7 +315,6 @@ void replaceBeanByNameWithMatchingBeanDefinitionRetainsPrimaryAndFallbackFlags()
 
 		assertThatNoException().isThrownBy(context::refresh);
 		assertThat(context.getBeanDefinition("descriptionBean"))
-				.isNotSameAs(definition)
 				.matches(BeanDefinition::isPrimary, "isPrimary")
 				.matches(BeanDefinition::isFallback, "isFallback")
 				.satisfies(d -> assertThat(d.getScope()).isEqualTo(""))
@@ -324,9 +323,8 @@ void replaceBeanByNameWithMatchingBeanDefinitionRetainsPrimaryAndFallbackFlags()
 	}
 
 	@Test
-	void qualifiedElementIsSetToBeanOverrideField() {
+	void qualifiedElementIsSetToBeanOverrideFieldForNonexistentBeanDefinition() {
 		AnnotationConfigApplicationContext context = createContext(CaseByNameWithQualifier.class);
-		context.registerBeanDefinition("descriptionBean", new RootBeanDefinition(String.class, () -> "ORIGINAL"));
 
 		assertThatNoException().isThrownBy(context::refresh);
 		assertThat(context.getBeanDefinition("descriptionBean"))
@@ -398,9 +396,12 @@ static class CaseOverrideBeanProducedByFactoryBean {
 	static class CaseByNameWithQualifier {
 
 		@Qualifier("preferThis")
-		@DummyBean(beanName = "descriptionBean")
+		@TestBean(name = "descriptionBean", enforceOverride = false)
 		private String description;
 
+		static String descriptionBean() {
+			return "overridden";
+		}
 	}
 
 	static class TestFactoryBean implements FactoryBean<Object> {