When to use @RunWith and when @ExtendWith

Question

My team and I have been working on a bunch of microservices using Spring boot. Since the services went through JUnit and Spring Boot upgrades (We're using now Spring Boot 2 and JUnit 5), different JUnit implemented by different devs, are now using different patterns with:

• @ExtendWith
• @RunWith

Today what's the difference between the two of them and do we really need them for our Unit Tests or are embedded in some new Spring Boot annotation?

Answer 1

If you are using Junit version < 5, so you have to use @RunWith(SpringRunner.class) or @RunWith(MockitoJUnitRunner.class) etc.

If you are using Junit version = 5, so you have to use @ExtendWith(SpringExtension.class) or @ExtendWith(MockitoExtension.class) etc.

1. SpringRunner
2. MockitoJUnitRunner
3. SpringExtension
4. MockitoExtension

Answer 2

The answer can be found in the documentation:

If you are using JUnit 4, don’t forget to 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 @…Testannotations are already annotated with it

.