Support @MockBean/@SpyBean with @Primary

Update `MockitoPostProcessor` so that `@MockBean` and `@SpyBean`
work consistently when combined with `@Primary`.

See gh-11077
Co-authored-by: Andreas Neiser <andreas.neiser@gmail.com>

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/mock/mockito/MockitoPostProcessor.java

@@ -19,6 +19,7 @@ package org.springframework.boot.test.mock.mockito;
 import java.beans.PropertyDescriptor;
 import java.lang.reflect.Field;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.HashMap;
 import java.util.LinkedHashMap;
 import java.util.LinkedHashSet;
@@ -184,6 +185,8 @@ public class MockitoPostProcessor extends InstantiationAwareBeanPostProcessorAda
 		String beanName = getBeanName(beanFactory, registry, definition, beanDefinition);
 		String transformedBeanName = BeanFactoryUtils.transformedBeanName(beanName);
 		if (registry.containsBeanDefinition(transformedBeanName)) {
+			BeanDefinition existing = registry.getBeanDefinition(transformedBeanName);
+			copyBeanDefinitionDetails(existing, beanDefinition);
 			registry.removeBeanDefinition(transformedBeanName);
 		}
 		registry.registerBeanDefinition(transformedBeanName, beanDefinition);
@@ -196,6 +199,10 @@ public class MockitoPostProcessor extends InstantiationAwareBeanPostProcessorAda
 		}
 	}
 
+	private void copyBeanDefinitionDetails(BeanDefinition from, RootBeanDefinition to) {
+		to.setPrimary(from.isPrimary());
+	}
+
 	private RootBeanDefinition createBeanDefinition(MockDefinition mockDefinition) {
 		RootBeanDefinition definition = new RootBeanDefinition(
 				mockDefinition.getTypeToMock().resolve());
@@ -212,13 +219,19 @@ public class MockitoPostProcessor extends InstantiationAwareBeanPostProcessorAda
 		if (StringUtils.hasLength(mockDefinition.getName())) {
 			return mockDefinition.getName();
 		}
-		Set<String> existingBeans = findCandidateBeans(beanFactory, mockDefinition);
+		Set<String> existingBeans = findCandidateBeans(beanFactory,
+				mockDefinition.getTypeToMock(), mockDefinition.getQualifier());
 		if (existingBeans.isEmpty()) {
 			return this.beanNameGenerator.generateBeanName(beanDefinition, registry);
 		}
 		if (existingBeans.size() == 1) {
 			return existingBeans.iterator().next();
 		}
+		String primaryCandidate = determinePrimaryCandidate(registry, existingBeans,
+				mockDefinition.getTypeToMock());
+		if (primaryCandidate != null) {
+			return primaryCandidate;
+		}
 		throw new IllegalStateException(
 				"Unable to register mock bean " + mockDefinition.getTypeToMock()
 						+ " expected a single matching bean to replace but found "
@@ -226,22 +239,21 @@ public class MockitoPostProcessor extends InstantiationAwareBeanPostProcessorAda
 	}
 
 	private void registerSpy(ConfigurableListableBeanFactory beanFactory,
-			BeanDefinitionRegistry registry, SpyDefinition definition, Field field) {
-		String[] existingBeans = getExistingBeans(beanFactory, definition.getTypeToSpy());
+			BeanDefinitionRegistry registry, SpyDefinition spyDefinition, Field field) {
+		Set<String> existingBeans = findCandidateBeans(beanFactory,
+				spyDefinition.getTypeToSpy(), spyDefinition.getQualifier());
 		if (ObjectUtils.isEmpty(existingBeans)) {
-			createSpy(registry, definition, field);
+			createSpy(registry, spyDefinition, field);
 		}
 		else {
-			registerSpies(registry, definition, field, existingBeans);
+			registerSpies(registry, spyDefinition, field, existingBeans);
 		}
 	}
 
 	private Set<String> findCandidateBeans(ConfigurableListableBeanFactory beanFactory,
-			MockDefinition mockDefinition) {
-		QualifierDefinition qualifier = mockDefinition.getQualifier();
+			ResolvableType type, QualifierDefinition qualifier) {
 		Set<String> candidates = new TreeSet<>();
-		for (String candidate : getExistingBeans(beanFactory,
-				mockDefinition.getTypeToMock())) {
+		for (String candidate : getExistingBeans(beanFactory, type)) {
 			if (qualifier == null || qualifier.matches(beanFactory, candidate)) {
 				candidates.add(candidate);
 			}
@@ -249,7 +261,7 @@ public class MockitoPostProcessor extends InstantiationAwareBeanPostProcessorAda
 		return candidates;
 	}
 
-	private String[] getExistingBeans(ConfigurableListableBeanFactory beanFactory,
+	private Set<String> getExistingBeans(ConfigurableListableBeanFactory beanFactory,
 			ResolvableType type) {
 		Set<String> beans = new LinkedHashSet<>(
 				Arrays.asList(beanFactory.getBeanNamesForType(type)));
@@ -263,7 +275,7 @@ public class MockitoPostProcessor extends InstantiationAwareBeanPostProcessorAda
 			}
 		}
 		beans.removeIf(this::isScopedTarget);
-		return StringUtils.toStringArray(beans);
+		return beans;
 	}
 
 	private boolean isScopedTarget(String beanName) {
@@ -275,49 +287,49 @@ public class MockitoPostProcessor extends InstantiationAwareBeanPostProcessorAda
 		}
 	}
 
-	private void createSpy(BeanDefinitionRegistry registry, SpyDefinition definition,
+	private void createSpy(BeanDefinitionRegistry registry, SpyDefinition spyDefinition,
 			Field field) {
 		RootBeanDefinition beanDefinition = new RootBeanDefinition(
-				definition.getTypeToSpy().resolve());
+				spyDefinition.getTypeToSpy().resolve());
 		String beanName = this.beanNameGenerator.generateBeanName(beanDefinition,
 				registry);
 		registry.registerBeanDefinition(beanName, beanDefinition);
-		registerSpy(definition, field, beanName);
+		registerSpy(spyDefinition, field, beanName);
 	}
 
-	private void registerSpies(BeanDefinitionRegistry registry, SpyDefinition definition,
-			Field field, String[] existingBeans) {
+	private void registerSpies(BeanDefinitionRegistry registry,
+			SpyDefinition spyDefinition, Field field, Collection<String> existingBeans) {
 		try {
-			registerSpy(definition, field,
-					determineBeanName(existingBeans, definition, registry));
+			String beanName = determineBeanName(existingBeans, spyDefinition, registry);
+			registerSpy(spyDefinition, field, beanName);
 		}
 		catch (RuntimeException ex) {
 			throw new IllegalStateException(
-					"Unable to register spy bean " + definition.getTypeToSpy(), ex);
+					"Unable to register spy bean " + spyDefinition.getTypeToSpy(), ex);
 		}
 	}
 
-	private String determineBeanName(String[] existingBeans, SpyDefinition definition,
-			BeanDefinitionRegistry registry) {
+	private String determineBeanName(Collection<String> existingBeans,
+			SpyDefinition definition, BeanDefinitionRegistry registry) {
 		if (StringUtils.hasText(definition.getName())) {
 			return definition.getName();
 		}
-		if (existingBeans.length == 1) {
-			return existingBeans[0];
+		if (existingBeans.size() == 1) {
+			return existingBeans.iterator().next();
 		}
 		return determinePrimaryCandidate(registry, existingBeans,
 				definition.getTypeToSpy());
 	}
 
 	private String determinePrimaryCandidate(BeanDefinitionRegistry registry,
-			String[] candidateBeanNames, ResolvableType type) {
+			Collection<String> candidateBeanNames, ResolvableType type) {
 		String primaryBeanName = null;
 		for (String candidateBeanName : candidateBeanNames) {
 			BeanDefinition beanDefinition = registry.getBeanDefinition(candidateBeanName);
 			if (beanDefinition.isPrimary()) {
 				if (primaryBeanName != null) {
 					throw new NoUniqueBeanDefinitionException(type.resolve(),
-							candidateBeanNames.length,
+							candidateBeanNames.size(),
 							"more than one 'primary' bean found among candidates: "
 									+ Arrays.asList(candidateBeanNames));
 				}