Autowire JUnit rule in integration test

Question

I have a piece of code which will be repeated across multiple integration tests. The code will run before and after tests. I have decided that using an JUnit @Rule would be the best way to achieve this.

The problem is that the rule will need to have access to few @Autowired Spring beans. (The tests are run with Spring Integration Test Runner so Autowire works fine.

I have a rule:

public class CustomSpringRule extends ExternalResource {
    private final SomeOtherBean someOtherBean;

    public CustomSpringRule(SomeOtherBean someOtherBean) {
        this.someOtherBean = someOtherBean;
    }

    @Override
    public void before() {
        someOtherBean.someMethod();
    }

    // ...
}

I have my context to which I have added my bean:

@Bean 
public CustomSpringRule getCustomSpringRule(SomeOtherBean someOtherBean) {
   return new CustomSpringRule(someOtherBean);
}

Finally I have just autowired the rule bean within test file:

@Autowire
@Rule
public CustomSpringRule customSpringRule;

It all works fine but I never really used the @Rule annotation and I am slightly concerned that JUnit reflection and Spring Autowire won't go well together or there will be some issues that are not obvious at first look.

Does anyone have any suggestions whether this is valid and safe?

Answer 1

I don't think you need @Rule here,

"I have a piece of code which will be repeated across multiple integration tests. The code will run before and after tests."

This can be achieved using JUnit's @Before and @After annotations. Methods annotated with these annotations will execute before/after every test. So you can call your common code from these methods.

Answer 2

Using auto-wired rules is fine – there are no problems or limitations with this approach.

Note: I you are using component scanning (which is e.g. enabled in @SpringBootTest), you can simplify the rule implementation like this:

@Component
public class CustomSpringRule extends ExternalResource {
    @Autowired
    private SomeOtherBean someOtherBean;

    @Override
    public void before() {
        someOtherBean.someMethod();
    }

    // ...
}