Spring context cache when using @AutoConfigure* annotations "breaks" on each test package

[loganmzz]

Spring Boot version: 1.5.4

When executing a test with Spring, it caches context based on a MergedContextConfiguration. When using an @AutoConfigure annotation, each test package generates a new application context instead of reusing an existing one that is supposed to match.

See https://github.com/loganmzz/spring-boot-context-cache-and-autoconfigure as an example.

After digging problem, I find that ImportsContextCustomizer adds AutoConfigurationPackages$PackageImport while finding a @Import(AutoConfigurationPackages.Registrar.class) into annotation "hierarchy":
From my example:

• DemoApplicationTests
  • @AutoConfigureJson
    • @ImportAutoConfiguration
      • @AutoConfigurationPackage
        • @Import(AutoConfigurationPackages.Registrar.class)

While @AutoConfigurationPackage is supposed to add annotated element package as a source. But in this case, it is unexpected but also cache key doesn't take into account real impact on configuration. If there no additional element, application context is supposed to be the same.

[philwebb]

Thanks for the same and for the analysis.

The cache key issue is quite subtle here. The @AutoConfigurationPackage is used to register a package that will be picked up things like JPA registration. This means that it could change the contents of the ApplicationContext so a different cache key is required.

I'm not convinced that @ImportAutoConfiguration should really be annotated with @AutoConfigurationPackage. It really services a different purpose and I don't think it totally makes sense.

The problem is that removing the annotation is potentially a breaking change and something that I don't think we should do in 1.5.x. It's unfortunate that extra contexts are created, but I think we might need to live with that until 2.0 is released.

[wilkinsona]

Isn't this a duplicate of #9282?

[philwebb]

Indeed, it's a duplicate of #9282