Can #ContextConfiguration in a custom annotation be merged? - spring-boot

Question

I am working on custom Spring Boot starters. In a test starter what I wanted do to is to implement a composed annotation, which would add additional #Configuration classes to the ApplicationContext (and possibly use this annotation in a TestExecutionListener). ex:
#Retention(RetentionPolicy.RUNTIME)
#Target(ElementType.TYPE)
#ContextConfiguration(classes = AdditionalTestConfiguration.class)
public #interface ComposedAnnotation {
}
And use that in my Spring Boot integration test:
#RunWith(SpringJUnit4ClassRunner.class)
#WebIntegrationTest
#SpringApplicationConfiguration(Application.class)
#ComposedAnnotation
public class SomeTest {
}
No inheritance is involved. Unfortunately, it does not seem to work. I doubt it's a Spring Boot thing, rather Spring testing framework itself.
Is there any way I can achieve expected result?

Answer 1

You're right: this is not an issue with Spring Boot. But it's also not an issue with spring-test.
Rather, it's the intended behavior of Spring in general. For details, check out my answer to this question: #ActiveProfiles in meta annotation and on test class not working
In summary, you cannot achieve this with two #ContextConfiguration annotations declared on an individual test class (either directly or as meta-annotations).
However, I just came up with a trick that will allow you to achieve this. Specifically, you can create an ApplicationContextInitializer (ACI) that registers one or more #Configuration classes. In your composed annotation, you can then register this ACI to register the always present #Configuration classes. And when the composed annotation is actually used, it can declare additional #Configuration classes like normal.
I just submitted a working example in this commit.
Basically, the code would look something like this:
#ContextConfiguration(loader = AnnotationConfigContextLoader.class, initializers = FooConfigInitializer.class)
#Retention(RetentionPolicy.RUNTIME)
#Target(ElementType.TYPE)
public #interface ComposedContextConfiguration {
#AliasFor(annotation = ContextConfiguration.class, attribute = "classes")
Class<?>[] value() default {};
}
public class FooConfigInitializer implements ApplicationContextInitializer<GenericApplicationContext> {
#Override
public void initialize(GenericApplicationContext applicationContext) {
new AnnotatedBeanDefinitionReader(applicationContext).register(FooConfig.class);
}
}
And you can use it like this:
#RunWith(SpringRunner.class)
#ComposedContextConfiguration(BarConfig.class)
public class InitializerConfiguredViaMetaAnnotationTests { /* ... */ }
Your ApplicationContext will then be loaded from FooConfig and BarConfig.
The above examples obviously do not use Spring Boot, but the same principles should also be applicable to #SpringApplicationConfiguration.
Regards,
Sam (author of the Spring TestContext Framework)