spring - What does this do: @RunWith(SpringJUnit4ClassRunner.class)

Question

What does this annotation do?
When would I want to use it?
When would I not want to use it?

@RunWith(SpringJUnit4ClassRunner.class)

I can find more usages of this when I Google and do not find a 101 explanation as to what this annotation is supposed to communicate to me or when/why I would use it?

Answer 1

The annotation is used to configure a unit test that required Spring's dependency injection.

From Spring Reference - 10. Unit Testing:

10.1 Creating a Unit Test Class

In order for the unit test to run a batch job, the framework must load the job's ApplicationContext. Two annotations are used to trigger this:

@RunWith(SpringJUnit4ClassRunner.class): Indicates that the class should use Spring's JUnit facilities.

@ContextConfiguration(locations = {...}): Indicates which XML files contain the ApplicationContext.