Explore JUnit 5 integration

[sdeleuze]

Currently, Spring Fu applications are tested mainly in 2 ways:

• Unit tests for individual classes is made easy by generalized constructor injection usage, potentially with Mocking, without ApplicationContext being involved (we need to add examples of that as part of Allow to customize an existing application (for tests, mocking, etc.) #44).
• Integration tests by just running the application, eventually with a specified profile like in this example.

Even if Spring Fu is designed to be testable with not specific support, we should explore if JUnit 5 integration makes sense.

@sbrannen Since Spring Fu is heavily based on ApplicationContextInitializer, is there something already supported in SpringExtension we could leverage to register beans on the context and take advantage of test classes @Autowired support for example?

[wilkinsona]

to register beans on the context and take advantage of test classes @Autowired support for example

If Spring Fu built on top of Boot, which I think it should, you'd benefit from the change that's currently proposed in spring-projects/spring-boot#8115 (comment). Note the custom BeanDefinitionLoader in the repository that @dsyer links to in his comment.

[sbrannen]

Since Spring Fu is heavily based on ApplicationContextInitializer, is there something already supported in SpringExtension we could leverage to register beans on the context and take advantage of test classes @Autowired support for example?

Sure, there are two major options here.

You can register an ApplicationContextInitializer via @ContextConfiguration(initializers = ...).

You can make use of an auto-detected ContextCustomizer. That's actually what Spring Boot Test does, and it was the original PR from @philwebb that got that into the Spring TestContext Framework.

Using an ApplicationContextInitializer would typically require that the end user register it explicitly for each test class; whereas, a ContextCustomizer can be registered automatically by the Spring Fu framework.

These features are of course not specific to JUnit Jupiter. Only the support for constructor and method injection of such beans would be specific to the SpringExtension.

Does one of those options work for you?

[sdeleuze]

Thanks for your feedback @wilkinsona and @sbrannen, we are going to try to leverage Boot for that indeed.

[sdeleuze]

Typical Spring Fu tests are just plain JUnit 5 tests + Spring Fu is now based on Boot so I close this issue.