`@TestBean` and `@MockitoBean` tests fail in AOT mode

[sbrannen]

Overview

When running various bean override tests in AOT mode (via AotIntegrationTests), AOT processing fails with a stack trace similar to the following.

org.springframework.test.context.aot.TestContextAotException: Failed to generate AOT artifacts for test classes [org.springframework.test.context.bean.override.convention.TestBeanByTypeIntegrationTests]
	at org.springframework.test.context.aot.TestContextAotGenerator.lambda$10(TestContextAotGenerator.java:281)
	at java.base/java.util.LinkedHashMap.forEach(LinkedHashMap.java:721)
	at org.springframework.util.MultiValueMapAdapter.forEach(MultiValueMapAdapter.java:179)
	at org.springframework.test.context.aot.TestContextAotGenerator.processAheadOfTime(TestContextAotGenerator.java:244)
	at org.springframework.test.context.aot.TestContextAotGenerator.processAheadOfTime(TestContextAotGenerator.java:205)
	at org.springframework.test.context.aot.AotIntegrationTests.runEndToEndTests(AotIntegrationTests.java:166)
	at org.springframework.test.context.aot.AotIntegrationTests.endToEndTestsForSelectedTestClasses(AotIntegrationTests.java:159)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at org.springframework.core.test.tools.CompileWithForkedClassLoaderExtension.intercept(CompileWithForkedClassLoaderExtension.java:97)
	at org.springframework.core.test.tools.CompileWithForkedClassLoaderExtension.interceptTestMethod(CompileWithForkedClassLoaderExtension.java:83)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
Caused by: org.springframework.test.context.aot.TestContextAotException: Failed to process test class [org.springframework.test.context.bean.override.convention.TestBeanByTypeIntegrationTests] for AOT
	at org.springframework.test.context.aot.TestContextAotGenerator.processAheadOfTime(TestContextAotGenerator.java:317)
	at org.springframework.test.context.aot.TestContextAotGenerator.lambda$10(TestContextAotGenerator.java:273)
	... 11 more
Caused by: java.lang.IllegalStateException: No constructor or factory method candidate found for Root bean: class [null]; scope=singleton; abstract=false; lazyInit=null; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodNames=null; destroyMethodNames=null and argument types []
	at org.springframework.beans.factory.support.ConstructorResolver.resolveConstructorOrFactoryMethod(ConstructorResolver.java:996)
	at org.springframework.beans.factory.support.RegisteredBean.resolveConstructorOrFactoryMethod(RegisteredBean.java:218)
	at org.springframework.beans.factory.support.RegisteredBean.resolveInstantiationDescriptor(RegisteredBean.java:228)
	at org.springframework.util.function.SingletonSupplier.get(SingletonSupplier.java:106)
	at org.springframework.beans.factory.aot.DefaultBeanRegistrationCodeFragments.getTarget(DefaultBeanRegistrationCodeFragments.java:86)
	at org.springframework.beans.factory.aot.BeanDefinitionMethodGenerator.generateBeanDefinitionMethod(BeanDefinitionMethodGenerator.java:85)
	at org.springframework.beans.factory.aot.BeanRegistrationsAotContribution.lambda$3(BeanRegistrationsAotContribution.java:89)
	at java.base/java.util.LinkedHashMap.forEach(LinkedHashMap.java:721)
	at org.springframework.beans.factory.aot.BeanRegistrationsAotContribution.generateRegisterBeanDefinitionsMethod(BeanRegistrationsAotContribution.java:87)
	at org.springframework.beans.factory.aot.BeanRegistrationsAotContribution.lambda$1(BeanRegistrationsAotContribution.java:72)
	at org.springframework.aot.generate.GeneratedMethod.<init>(GeneratedMethod.java:54)
	at org.springframework.aot.generate.GeneratedMethods.add(GeneratedMethods.java:112)
	at org.springframework.aot.generate.GeneratedMethods.add(GeneratedMethods.java:89)
	at org.springframework.beans.factory.aot.BeanRegistrationsAotContribution.applyTo(BeanRegistrationsAotContribution.java:71)
	at org.springframework.context.aot.BeanFactoryInitializationAotContributions.applyTo(BeanFactoryInitializationAotContributions.java:78)
	at org.springframework.context.aot.ApplicationContextAotGenerator.lambda$0(ApplicationContextAotGenerator.java:58)
	at org.springframework.context.aot.ApplicationContextAotGenerator.withCglibClassHandler(ApplicationContextAotGenerator.java:67)
	at org.springframework.context.aot.ApplicationContextAotGenerator.processAheadOfTime(ApplicationContextAotGenerator.java:53)
	at org.springframework.test.context.aot.TestContextAotGenerator.processAheadOfTime(TestContextAotGenerator.java:314)
	... 12 more

The key part is this:

No constructor or factory method candidate found for Root bean: class [null]; scope=singleton; abstract=false; lazyInit=null; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodNames=null; destroyMethodNames=null and argument types []

... which seems like a relatively empty BeanDefinition.

Failing Test Classes

• TestBeanByTypeIntegrationTests
• TestBeanInheritanceIntegrationTests$ConcreteTestBeanIntegrationTests
• MockitoBeanByTypeIntegrationTests
• MockitoBeanIntegrationTests

Related Issues

• Support Mockito with @MockBean and @SpyBean in AOT-processed tests spring-boot#32195
• Verify AOT testing support for all tests in the spring-test module #29122
• Introduce dedicated AOT tests for bean override support in the TCF #32932

[snicoll]

Quoting #32933:

Although @MockitoBean and @MockitoSpyBean will not work out-of-the-box within a GraalVM native image due to their dependency on Mockito, the general Bean Override support for tests should ideally work within a native image.

That is partially accurate. The mockito support in Spring Boot never worked in AOT mode on the JVM. It current fails as follows:

Caused by: org.springframework.aot.generate.UnsupportedTypeValueCodeGenerationException: Code generation does not support org.springframework.boot.test.mock.mockito.MockDefinition
	at org.springframework.aot.generate.ValueCodeGenerator.generateCode(ValueCodeGenerator.java:113)
	... 42 more

That is because the TCF requires the key for a context to be computed at a certain time and makes it very AOT unfriendly as a result. I think this issue needs to be requalified as we need to fix that.

Next up, the support works by registering a singleton with a "dummy" bean definition and that's why this is failing.