Register `AutoConfigurations` using fully qualified class name

Update `AbstractApplicationContextRunner` and `Configurations` to
allow registration of beans with a specific generated bean name. By
default, no name is generated, however, `AutoConfigurations` has been
updated to use bean names using the fully qualified class name.

The update brings `ApplicationContextRunners` closer the behavior of
a standard Spring Boot application where user `@Configuration` classes
are usually registered with a simple name and auto-configurations are
imported (via an `ImportSelector`) using a fully qualified name.

Fixes gh-17963

Co-authored-by: Stéphane Nicoll <stephane.nicoll@broadcom.com>
Co-authored-by: Andy Wilkinson <andy.wilkinson@broadcom.com>
Co-authored-by: Dmytro Nosan <dimanosan@gmail.com>

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/AutoConfigurations.java

@@ -51,7 +51,7 @@ public class AutoConfigurations extends Configurations implements Ordered {
 	}
 
 	AutoConfigurations(UnaryOperator<String> replacementMapper, Collection<Class<?>> classes) {
-		super(sorter(replacementMapper), classes);
+		super(sorter(replacementMapper), classes, Class::getName);
 		this.replacementMapper = replacementMapper;
 	}
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/AutoConfigurationsTests.java

@@ -54,6 +54,12 @@ class AutoConfigurationsTests {
 				AutoConfigureA.class);
 	}
 
+	@Test
+	void getBeanNameShouldUseClassName() {
+		Configurations configurations = AutoConfigurations.of(AutoConfigureA.class, AutoConfigureB.class);
+		assertThat(configurations.getBeanName(AutoConfigureA.class)).isEqualTo(AutoConfigureA.class.getName());
+	}
+
 	private String replaceB(String className) {
 		return (!AutoConfigureB.class.getName().equals(className)) ? className : AutoConfigureB2.class.getName();
 	}

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/context/runner/AbstractApplicationContextRunner.java

@@ -19,6 +19,7 @@ package org.springframework.boot.test.context.runner;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.function.BiConsumer;
 import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.function.Supplier;
@@ -27,6 +28,7 @@ import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.config.BeanDefinitionCustomizer;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 import org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory;
+import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.beans.factory.support.BeanNameGenerator;
 import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.boot.context.annotation.Configurations;
@@ -38,12 +40,14 @@ import org.springframework.boot.test.util.TestPropertyValues;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextInitializer;
 import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.annotation.AnnotatedBeanDefinitionReader;
 import org.springframework.context.annotation.AnnotationConfigRegistry;
 import org.springframework.context.support.GenericApplicationContext;
 import org.springframework.core.ResolvableType;
 import org.springframework.core.env.Environment;
 import org.springframework.core.io.DefaultResourceLoader;
 import org.springframework.util.Assert;
+import org.springframework.util.CollectionUtils;
 
 /**
  * Utility design to run an {@link ApplicationContext} and provide AssertJ style
@@ -439,15 +443,27 @@ public abstract class AbstractApplicationContextRunner<SELF extends AbstractAppl
 		this.runnerConfiguration.environmentProperties.applyTo(context);
 		this.runnerConfiguration.beanRegistrations.forEach((registration) -> registration.apply(context));
 		this.runnerConfiguration.initializers.forEach((initializer) -> initializer.initialize(context));
-		Class<?>[] classes = Configurations.getClasses(this.runnerConfiguration.configurations);
+		if (!CollectionUtils.isEmpty(this.runnerConfiguration.configurations)) {
-		if (classes.length > 0) {
+			BiConsumer<Class<?>, String> registrar = getRegistrar(context);
-			((AnnotationConfigRegistry) context).register(classes);
+			for (Configurations configurations : Configurations.collate(this.runnerConfiguration.configurations)) {
+				for (Class<?> beanClass : Configurations.getClasses(configurations)) {
+					String beanName = configurations.getBeanName(beanClass);
+					registrar.accept(beanClass, beanName);
+				}
+			}
 		}
 		if (refresh) {
 			context.refresh();
 		}
 	}
 
+	private BiConsumer<Class<?>, String> getRegistrar(C context) {
+		if (context instanceof BeanDefinitionRegistry registry) {
+			return new AnnotatedBeanDefinitionReader(registry, context.getEnvironment())::registerBean;
+		}
+		return (beanClass, beanName) -> ((AnnotationConfigRegistry) context).register(beanClass);
+	}
+
 	private void accept(ContextConsumer<? super A> consumer, A context) {
 		try {
 			consumer.accept(context);

spring-boot-project/spring-boot-test/src/test/java/org/springframework/boot/test/context/example/duplicate/first/EmptyConfig.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2012-2024 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.test.context.example.duplicate.first;
+
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * Example configuration to showcase handing of duplicate class names.
+ *
+ * @author Stephane Nicoll
+ */
+@Configuration
+public class EmptyConfig {
+
+}

spring-boot-project/spring-boot-test/src/test/java/org/springframework/boot/test/context/example/duplicate/second/EmptyConfig.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2012-2024 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.test.context.example.duplicate.second;
+
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * Example configuration to showcase handing of duplicate class names.
+ *
+ * @author Stephane Nicoll
+ */
+@Configuration
+public class EmptyConfig {
+
+}

spring-boot-project/spring-boot-test/src/test/java/org/springframework/boot/test/context/runner/AbstractApplicationContextRunnerTests.java

@@ -17,6 +17,9 @@
 package org.springframework.boot.test.context.runner;
 
 import java.io.IOException;
+import java.util.Collection;
+import java.util.List;
+import java.util.Set;
 import java.util.UUID;
 import java.util.concurrent.atomic.AtomicBoolean;
 
@@ -27,6 +30,8 @@ import org.springframework.beans.factory.BeanCurrentlyInCreationException;
 import org.springframework.beans.factory.BeanDefinitionStoreException;
 import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.support.BeanDefinitionOverrideException;
+import org.springframework.boot.context.annotation.Configurations;
 import org.springframework.boot.context.annotation.UserConfigurations;
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
@@ -139,6 +144,38 @@ abstract class AbstractApplicationContextRunnerTests<T extends AbstractApplicati
 		get().withUserConfiguration(FooConfig.class).run((context) -> assertThat(context).hasBean("foo"));
 	}
 
+	@Test
+	void runWithUserConfigurationsRegistersDefaultBeanName() {
+		get().withUserConfiguration(FooConfig.class)
+			.run((context) -> assertThat(context).hasBean("abstractApplicationContextRunnerTests.FooConfig"));
+	}
+
+	@Test
+	void runWithUserConfigurationsWhenHasSameShortClassNamedRegistersWithoutBeanName() {
+		get()
+			.withUserConfiguration(org.springframework.boot.test.context.example.duplicate.first.EmptyConfig.class,
+					org.springframework.boot.test.context.example.duplicate.second.EmptyConfig.class)
+			.run((context) -> assertThat(context.getStartupFailure())
+				.isInstanceOf(BeanDefinitionOverrideException.class));
+	}
+
+	@Test
+	void runFullyQualifiedNameConfigurationsRegistersFullyQualifiedBeanName() {
+		get().withConfiguration(FullyQualifiedNameConfigurations.of(FooConfig.class))
+			.run((context) -> assertThat(context).hasBean(FooConfig.class.getName()));
+	}
+
+	@Test
+	void runWithFullyQualifiedNameConfigurationsWhenHasSameShortClassNamedRegistersWithFullyQualifiedBeanName() {
+		get()
+			.withConfiguration(FullyQualifiedNameConfigurations.of(
+					org.springframework.boot.test.context.example.duplicate.first.EmptyConfig.class,
+					org.springframework.boot.test.context.example.duplicate.second.EmptyConfig.class))
+			.run((context) -> assertThat(context)
+				.hasSingleBean(org.springframework.boot.test.context.example.duplicate.first.EmptyConfig.class)
+				.hasSingleBean(org.springframework.boot.test.context.example.duplicate.second.EmptyConfig.class));
+	}
+
 	@Test
 	void runWithUserNamedBeanShouldRegisterBean() {
 		get().withBean("foo", String.class, () -> "foo").run((context) -> assertThat(context).hasBean("foo"));
@@ -384,4 +421,21 @@ abstract class AbstractApplicationContextRunnerTests<T extends AbstractApplicati
 
 	}
 
+	static class FullyQualifiedNameConfigurations extends Configurations {
+
+		protected FullyQualifiedNameConfigurations(Collection<Class<?>> classes) {
+			super(null, classes, Class::getName);
+		}
+
+		@Override
+		protected Configurations merge(Set<Class<?>> mergedClasses) {
+			return new FullyQualifiedNameConfigurations(mergedClasses);
+		}
+
+		static FullyQualifiedNameConfigurations of(Class<?>... classes) {
+			return new FullyQualifiedNameConfigurations(List.of(classes));
+		}
+
+	}
+
 }

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/annotation/Configurations.java

@@ -25,6 +25,7 @@ import java.util.LinkedHashSet;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Set;
+import java.util.function.Function;
 import java.util.function.UnaryOperator;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
@@ -65,6 +66,8 @@ public abstract class Configurations {
 
 	private final Set<Class<?>> classes;
 
+	private final Function<Class<?>, String> beanNameGenerator;
+
 	/**
 	 * Create a new {@link Configurations} instance.
 	 * @param classes the configuration classes
@@ -74,20 +77,28 @@ public abstract class Configurations {
 		Collection<Class<?>> sorted = sort(classes);
 		this.sorter = null;
 		this.classes = Collections.unmodifiableSet(new LinkedHashSet<>(sorted));
+		this.beanNameGenerator = null;
 	}
 
 	/**
 	 * Create a new {@link Configurations} instance.
 	 * @param sorter a {@link UnaryOperator} used to sort the configurations
 	 * @param classes the configuration classes
+	 * @param beanNameGenerator an optional function used to generate the bean name
 	 * @since 3.4.0
 	 */
-	protected Configurations(UnaryOperator<Collection<Class<?>>> sorter, Collection<Class<?>> classes) {
+	protected Configurations(UnaryOperator<Collection<Class<?>>> sorter, Collection<Class<?>> classes,
-		Assert.notNull(sorter, "Sorter must not be null");
+			Function<Class<?>, String> beanNameGenerator) {
 		Assert.notNull(classes, "Classes must not be null");
+		sorter = (sorter != null) ? sorter : UnaryOperator.identity();
 		Collection<Class<?>> sorted = sorter.apply(classes);
-		this.sorter = sorter;
+		this.sorter = (sorter != null) ? sorter : UnaryOperator.identity();
 		this.classes = Collections.unmodifiableSet(new LinkedHashSet<>(sorted));
+		this.beanNameGenerator = beanNameGenerator;
+	}
+
+	protected final Set<Class<?>> getClasses() {
+		return this.classes;
 	}
 
 	/**
@@ -95,17 +106,13 @@ public abstract class Configurations {
 	 * @param classes the classes to sort
 	 * @return a sorted set of classes
 	 * @deprecated since 3.4.0 for removal in 3.6.0 in favor of
-	 * {@link #Configurations(UnaryOperator, Collection)}
+	 * {@link #Configurations(UnaryOperator, Collection, Function)}
 	 */
 	@Deprecated(since = "3.4.0", forRemoval = true)
 	protected Collection<Class<?>> sort(Collection<Class<?>> classes) {
 		return classes;
 	}
 
-	protected final Set<Class<?>> getClasses() {
-		return this.classes;
-	}
-
 	/**
 	 * Merge configurations from another source of the same type.
 	 * @param other the other {@link Configurations} (must be of the same type as this
@@ -128,6 +135,17 @@ public abstract class Configurations {
 	 */
 	protected abstract Configurations merge(Set<Class<?>> mergedClasses);
 
+	/**
+	 * Return the bean name that should be used for the given configuration class or
+	 * {@code null} to use the default name.
+	 * @param beanClass the bean class
+	 * @return the bean name
+	 * @since 3.4.0
+	 */
+	public String getBeanName(Class<?> beanClass) {
+		return (this.beanNameGenerator != null) ? this.beanNameGenerator.apply(beanClass) : null;
+	}
+
 	/**
 	 * Return the classes from all the specified configurations in the order that they
 	 * would be registered.
@@ -145,30 +163,40 @@ public abstract class Configurations {
 	 * @return configuration classes in registration order
 	 */
 	public static Class<?>[] getClasses(Collection<Configurations> configurations) {
-		List<Configurations> ordered = new ArrayList<>(configurations);
+		List<Configurations> collated = collate(configurations);
-		ordered.sort(COMPARATOR);
-		List<Configurations> collated = collate(ordered);
 		LinkedHashSet<Class<?>> classes = collated.stream()
 			.flatMap(Configurations::streamClasses)
 			.collect(Collectors.toCollection(LinkedHashSet::new));
 		return ClassUtils.toClassArray(classes);
 	}
 
-	private static Stream<Class<?>> streamClasses(Configurations configurations) {
+	/**
-		return configurations.getClasses().stream();
+	 * Collate the given configuration by sorting and merging them.
-	}
+	 * @param configurations the source configuration
-
+	 * @return the collated configurations
-	private static List<Configurations> collate(List<Configurations> orderedConfigurations) {
+	 * @since 3.4.0
+	 */
+	public static List<Configurations> collate(Collection<Configurations> configurations) {
 		LinkedList<Configurations> collated = new LinkedList<>();
-		for (Configurations item : orderedConfigurations) {
+		for (Configurations configuration : sortConfigurations(configurations)) {
-			if (collated.isEmpty() || collated.getLast().getClass() != item.getClass()) {
+			if (collated.isEmpty() || collated.getLast().getClass() != configuration.getClass()) {
-				collated.add(item);
+				collated.add(configuration);
 			}
 			else {
-				collated.set(collated.size() - 1, collated.getLast().merge(item));
+				collated.set(collated.size() - 1, collated.getLast().merge(configuration));
 			}
 		}
 		return collated;
 	}
 
+	private static List<Configurations> sortConfigurations(Collection<Configurations> configurations) {
+		List<Configurations> sorted = new ArrayList<>(configurations);
+		sorted.sort(COMPARATOR);
+		return sorted;
+	}
+
+	private static Stream<Class<?>> streamClasses(Configurations configurations) {
+		return configurations.getClasses().stream();
+	}
+
 }

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/annotation/ConfigurationsTests.java

@@ -23,7 +23,9 @@ import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.List;
 import java.util.Set;
+import java.util.function.Function;
 import java.util.function.UnaryOperator;
 
 import org.junit.jupiter.api.Test;
@@ -87,6 +89,18 @@ class ConfigurationsTests {
 				OutputStream.class, String.class);
 	}
 
+	@Test
+	void getBeanNameWhenNoFunctionReturnsNull() {
+		Configurations configurations = new TestConfigurations(Short.class);
+		assertThat(configurations.getBeanName(Short.class)).isNull();
+	}
+
+	@Test
+	void getBeanNameWhenFunctionReturnsBeanName() {
+		Configurations configurations = new TestConfigurations(Sorter.instance, List.of(Short.class), Class::getName);
+		assertThat(configurations.getBeanName(Short.class)).isEqualTo(Short.class.getName());
+	}
+
 	@Order(Ordered.HIGHEST_PRECEDENCE)
 	static class TestConfigurations extends Configurations {
 
@@ -95,7 +109,12 @@ class ConfigurationsTests {
 		}
 
 		TestConfigurations(UnaryOperator<Collection<Class<?>>> sorter, Class<?>... classes) {
-			super(sorter, Arrays.asList(classes));
+			this(sorter, Arrays.asList(classes), null);
+		}
+
+		TestConfigurations(UnaryOperator<Collection<Class<?>>> sorter, Collection<Class<?>> classes,
+				Function<Class<?>, String> beanNameGenerator) {
+			super(sorter, classes, beanNameGenerator);
 		}
 
 		TestConfigurations(Collection<Class<?>> classes) {
@@ -117,7 +136,7 @@ class ConfigurationsTests {
 		}
 
 		protected TestSortedConfigurations(Collection<Class<?>> classes) {
-			super(Sorter.instance, classes);
+			super(Sorter.instance, classes, null);
 		}
 
 		@Override