Merge branch '3.4.x'

Closes gh-44482

Author: snicoll

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2024 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -19,11 +19,19 @@
 import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 import java.util.function.Consumer;
 
+import org.springframework.aot.generate.GenerationContext;
+import org.springframework.aot.hint.ExecutableMode;
+import org.springframework.aot.hint.ReflectionHints;
 import org.springframework.beans.BeanUtils;
+import org.springframework.beans.factory.aot.BeanFactoryInitializationAotContribution;
+import org.springframework.beans.factory.aot.BeanFactoryInitializationAotProcessor;
+import org.springframework.beans.factory.aot.BeanFactoryInitializationCode;
+import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 import org.springframework.boot.ApplicationContextFactory;
 import org.springframework.boot.Banner;
 import org.springframework.boot.ConfigurableBootstrapContext;
@@ -158,20 +166,23 @@ private Method getMainMethod(MergedContextConfiguration mergedConfig, UseMainMet
 			.orElse(null);
 		Assert.state(springBootConfiguration != null || useMainMethod == UseMainMethod.WHEN_AVAILABLE,
 				"Cannot use main method as no @SpringBootConfiguration-annotated class is available");
-		Method mainMethod = (springBootConfiguration != null)
-				? ReflectionUtils.findMethod(springBootConfiguration, "main", String[].class) : null;
+		Method mainMethod = findMainMethod(springBootConfiguration);
+		Assert.state(mainMethod != null || useMainMethod == UseMainMethod.WHEN_AVAILABLE,
+				() -> "Main method not found on '%s'".formatted(springBootConfiguration.getName()));
+		return mainMethod;
+	}
+
+	private static Method findMainMethod(Class<?> type) {
+		Method mainMethod = (type != null) ? ReflectionUtils.findMethod(type, "main", String[].class) : null;
 		if (mainMethod == null && KotlinDetector.isKotlinPresent()) {
 			try {
-				Class<?> kotlinClass = ClassUtils.forName(springBootConfiguration.getName() + "Kt",
-						springBootConfiguration.getClassLoader());
+				Class<?> kotlinClass = ClassUtils.forName(type.getName() + "Kt", type.getClassLoader());
 				mainMethod = ReflectionUtils.findMethod(kotlinClass, "main", String[].class);
 			}
 			catch (ClassNotFoundException ex) {
 				// Ignore
 			}
 		}
-		Assert.state(mainMethod != null || useMainMethod == UseMainMethod.WHEN_AVAILABLE,
-				() -> "Main method not found on '%s'".formatted(springBootConfiguration.getName()));
 		return mainMethod;
 	}
 
@@ -574,4 +585,39 @@ private ApplicationContext run(ThrowingSupplier<ConfigurableApplicationContext>
 
 	}
 
+	static class MainMethodBeanFactoryInitializationAotProcessor implements BeanFactoryInitializationAotProcessor {
+
+		@Override
+		public BeanFactoryInitializationAotContribution processAheadOfTime(
+				ConfigurableListableBeanFactory beanFactory) {
+			List<Method> mainMethods = new ArrayList<>();
+			for (String beanName : beanFactory.getBeanDefinitionNames()) {
+				Class<?> beanType = beanFactory.getType(beanName);
+				Method mainMethod = findMainMethod(beanType);
+				if (mainMethod != null) {
+					mainMethods.add(mainMethod);
+				}
+			}
+			return !mainMethods.isEmpty() ? new AotContribution(mainMethods) : null;
+		}
+
+		static class AotContribution implements BeanFactoryInitializationAotContribution {
+
+			private final Collection<Method> mainMethods;
+
+			AotContribution(Collection<Method> mainMethods) {
+				this.mainMethods = mainMethods;
+			}
+
+			@Override
+			public void applyTo(GenerationContext generationContext,
+					BeanFactoryInitializationCode beanFactoryInitializationCode) {
+				ReflectionHints reflectionHints = generationContext.getRuntimeHints().reflection();
+				this.mainMethods.forEach((method) -> reflectionHints.registerMethod(method, ExecutableMode.INVOKE));
+			}
+
+		}
+
+	}
+
 }

spring-boot-project/spring-boot-test/src/main/resources/META-INF/spring/aot.factories

@@ -0,0 +1,2 @@
+org.springframework.beans.factory.aot.BeanFactoryInitializationAotProcessor=\
+org.springframework.boot.test.context.SpringBootContextLoader.MainMethodBeanFactoryInitializationAotProcessor

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

@@ -25,10 +25,16 @@
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 
+import org.springframework.aot.hint.RuntimeHints;
+import org.springframework.aot.hint.predicate.RuntimeHintsPredicates;
+import org.springframework.aot.test.generate.TestGenerationContext;
 import org.springframework.beans.factory.BeanCreationException;
+import org.springframework.beans.factory.aot.BeanFactoryInitializationAotContribution;
+import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 import org.springframework.boot.ApplicationContextFactory;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.SpringBootConfiguration;
+import org.springframework.boot.test.context.SpringBootContextLoader.MainMethodBeanFactoryInitializationAotProcessor;
 import org.springframework.boot.test.context.SpringBootTest.UseMainMethod;
 import org.springframework.boot.test.util.TestPropertyValues;
 import org.springframework.boot.web.reactive.context.GenericReactiveWebApplicationContext;
@@ -244,6 +250,35 @@ void whenUseMainMethodWithContextHierarchyThrowsException() {
 			.withMessage("UseMainMethod.ALWAYS cannot be used with @ContextHierarchy tests");
 	}
 
+	@Test
+	void whenMainMethodPresentRegisterReflectionHints() {
+		TestContext testContext = new ExposedTestContextManager(UseMainMethodWhenAvailableAndNoMainMethod.class)
+			.getExposedTestContext();
+		ConfigurableListableBeanFactory beanFactory = (ConfigurableListableBeanFactory) testContext
+			.getApplicationContext()
+			.getAutowireCapableBeanFactory();
+		BeanFactoryInitializationAotContribution aotContribution = new MainMethodBeanFactoryInitializationAotProcessor()
+			.processAheadOfTime(beanFactory);
+		assertThat(aotContribution).isNull();
+	}
+
+	@Test
+	void whenMainMethodNotAvailableReturnsNoAotContribution() {
+		TestContext testContext = new ExposedTestContextManager(UseMainMethodWhenAvailableAndMainMethod.class)
+			.getExposedTestContext();
+		ConfigurableListableBeanFactory beanFactory = (ConfigurableListableBeanFactory) testContext
+			.getApplicationContext()
+			.getAutowireCapableBeanFactory();
+		BeanFactoryInitializationAotContribution aotContribution = new MainMethodBeanFactoryInitializationAotProcessor()
+			.processAheadOfTime(beanFactory);
+		assertThat(aotContribution).isNotNull();
+		TestGenerationContext generationContext = new TestGenerationContext();
+		aotContribution.applyTo(generationContext, null);
+		RuntimeHints runtimeHints = generationContext.getRuntimeHints();
+		assertThat(RuntimeHintsPredicates.reflection().onMethod(ConfigWithMain.class, "main").invoke())
+			.accepts(runtimeHints);
+	}
+
 	@Test
 	void whenSubclassProvidesCustomApplicationContextFactory() {
 		TestContext testContext = new ExposedTestContextManager(CustomApplicationContextTest.class)