Introduce enforceOverride flag in @⁠TestBean and @⁠MockitoBean

Prior to this commit, @⁠MockitoBean could be used to either create or
replace a bean definition, but @⁠TestBean could only be used to replace
a bean definition.

However, Bean Override implementations should require the presence of
an existing bean definition by default (i.e. literally "override" by
default), while giving the user the option to have a new bean
definition created if desired.

To address that, this commit introduces a new `enforceOverride`
attribute in @⁠TestBean and @⁠MockitoBean that defaults to true but
allows the user to decide if it's OK to create a bean for a nonexistent
bean definition.

Closes gh-33613

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

@@ -39,6 +39,9 @@ import static org.assertj.core.api.Assertions.assertThat;
 @SpringJUnitConfig
 public class TestBeanForByTypeLookupIntegrationTests {
 
+	@TestBean(enforceOverride = false)
+	MessageService messageService;
+
 	@TestBean
 	ExampleService anyNameForService;
 
@@ -50,6 +53,11 @@ public class TestBeanForByTypeLookupIntegrationTests {
 	@CustomQualifier
 	StringBuilder anyNameForStringBuilder2;
 
+
+	static MessageService messageService() {
+		return () -> "mocked nonexistent bean definition";
+	}
+
 	static ExampleService anyNameForService() {
 		return new RealExampleService("Mocked greeting");
 	}
@@ -63,6 +71,12 @@ public class TestBeanForByTypeLookupIntegrationTests {
 	}
 
 
+	@Test
+	void overrideIsFoundByTypeForNonexistentBeanDefinition(ApplicationContext ctx) {
+		assertThat(this.messageService).isSameAs(ctx.getBean(MessageService.class));
+		assertThat(this.messageService.getMessage()).isEqualTo("mocked nonexistent bean definition");
+	}
+
 	@Test
 	void overrideIsFoundByType(ApplicationContext ctx) {
 		assertThat(this.anyNameForService)
@@ -114,4 +128,10 @@ public class TestBeanForByTypeLookupIntegrationTests {
 		}
 	}
 
+	@FunctionalInterface
+	interface MessageService {
+
+		String getMessage();
+	}
+
 }

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

@@ -24,6 +24,7 @@ import org.junit.jupiter.api.Test;
 
 import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.core.ResolvableType;
+import org.springframework.test.context.bean.override.BeanOverrideStrategy;
 import org.springframework.test.context.bean.override.OverrideMetadata;
 import org.springframework.util.ReflectionUtils;
 import org.springframework.util.StringUtils;
@@ -124,7 +125,8 @@ class TestBeanOverrideMetadataTests {
 	private TestBeanOverrideMetadata createMetadata(Field field, Method overrideMethod) {
 		TestBean annotation = field.getAnnotation(TestBean.class);
 		String beanName = (StringUtils.hasText(annotation.name()) ? annotation.name() : null);
-		return new TestBeanOverrideMetadata(field, ResolvableType.forClass(field.getType()), beanName, overrideMethod);
+		return new TestBeanOverrideMetadata(
+				field, ResolvableType.forClass(field.getType()), beanName, BeanOverrideStrategy.REPLACE_DEFINITION, overrideMethod);
 	}
 
 	static class SampleOneOverride {

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

@@ -48,10 +48,10 @@ public class MockitoBeanForByNameLookupIntegrationTests {
 	@MockitoBean(name = "nestedField")
 	ExampleService renamed2;
 
-	@MockitoBean(name = "nonExistingBean")
+	@MockitoBean(name = "nonExistingBean", enforceOverride = false)
 	ExampleService nonExisting1;
 
-	@MockitoBean(name = "nestedNonExistingBean")
+	@MockitoBean(name = "nestedNonExistingBean", enforceOverride = false)
 	ExampleService nonExisting2;
 
 

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

@@ -48,10 +48,10 @@ import static org.mockito.Mockito.verifyNoMoreInteractions;
 @SpringJUnitConfig
 public class MockitoBeanForByTypeLookupIntegrationTests {
 
-	@MockitoBean
+	@MockitoBean(enforceOverride = false)
 	AnotherService serviceIsNotABean;
 
-	@MockitoBean
+	@MockitoBean(enforceOverride = false)
 	ExampleService anyNameForService;
 
 	@MockitoBean

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

@@ -93,7 +93,7 @@ class MockitoBeanSettingsStrictIntegrationTests {
 	@DirtiesContext
 	static class ImplicitStrictnessWithMockitoBean extends BaseCase {
 
-		@MockitoBean
+		@MockitoBean(enforceOverride = false)
 		@SuppressWarnings("unused")
 		DateTimeFormatter ignoredMock;
 	}