Document that JUnit 4 is the default

[Tetsuya3850]

I assumed the latest spring boot starter test uses JUnit 5 and had to scratch my head over it. I suggest adding it to the documentation as other people may be confused as well.

Reference
http://central.maven.org/maven2/org/springframework/boot/spring-boot-starter-test/2.1.4.RELEASE/spring-boot-starter-test-2.1.4.RELEASE.pom

[Tetsuya3850]

Add Note

This part seemed to imply that the latest is JUnit 5.

If you are using JUnit 4, don’t forget to also add @RunWith(SpringRunner.class) to your test, otherwise the annotations will be ignored. If you are using JUnit 5, there’s no need to add the equivalent @ExtendWith(SpringExtension.class) as @SpringBootTest and the other @…Test annotations are already annotated with it.

[wilkinsona]

Thanks for the suggestion. We already mention that JUnit 4 is the default in the Kotlin testing section. I can't see any harm in mentioning it more generally, but I think it would be better done in this section. If you agree, would you like to update your proposal?

[Tetsuya3850]

Ah,,, I have missed it since I do not use Kotlin. Yes, I will update my proposal based on your suggestion!

[Tetsuya3850]

I moved the doc to a more appropriate place!

[snicoll]

@Tetsuya3850 thank you, this is now merged in 2.1.x and master.