How to use @ComponentScan together with test-specific ContextConfigurations in SpringJunit4TestRunner?

Question

I am testing a Spring Boot application. I have several test classes, each of which needs a different set of mocked or otherwise customized beans.

Here is a sketch of

Answer 1

You may use additional explicit profiles to avoid such test configurations to be picked up (as suggested in another answer). I also did it and even created some library support for that.

However, Spring-Boot is clever and it has a built-in "type filter" to resolve this issue automatically. For this to work, you need to remove your @ComponentScan annotation, which would find your test configurations, and let the @SpringBootApplication do the work. In your example, just remove this:

@SpringBootApplication
@ComponentScan(
    basePackageClasses = {
            MyApplication.class,
            ImportantConfigurationFromSomeLibrary.class,
            ImportantConfigurationFromAnotherLibrary.class})

and replace it with:

@SpringBootApplication(scanBasePackageClasses= {
            MyApplication.class,
            ImportantConfigurationFromSomeLibrary.class,
            ImportantConfigurationFromAnotherLibrary.class})

You may also need to annotate your test as @SpringBootTest. This should avoid auto-scanning any inner-class configurations (and components) except for those residing in the current test.