Unit Test or Integration Test in Spring Boot

Nital :

I looked various tutorial online related to testing in Spring Boot and got confused by the way the tests were referred.

Some articles refer to controller tests that use @WebMvcTest annotation as Unit Test whereas some refer it as Integration Test. Not sure which one is correct.

Same questions applies to Repository layer test with @DataJpaTest.

I have following two tests written in my application, one for the controller and another one for the repository.

At the bottom I have some questions regarding both. Please guide.

UserControllerTest.java

@RunWith(SpringRunner.class)
@WebMvcTest(UserController.class)
public class UserControllerTest {

    @Autowired
    private MockMvc mockMvc;
    @MockBean
    private UserRepository userRepository;

    @Test
    public void signUp() throws Exception {
        this.mockMvc.perform(get("/signup")).andExpect(status().isOk());
    }

}

UserRepositoryTest.java

@RunWith(SpringRunner.class)
@DataJpaTest
public class UserRepositoryTest {

    @Autowired
    private TestEntityManager entityManager;
    @Autowired
    private UserRepository userRepository;

    @Test
    public void whenFindByName_thenReturnEmployee() {
        // given
        User u = new User();
        u.setName("ab");
        u.setEmail("[email protected]");
        entityManager.persistAndFlush(u);
        // when
        Optional<User> user = userRepository.findById(1L);
        // then
        assertTrue(user.isPresent());
    }

}

My questions are:

1. Does the annotation @WebMvcTest, @DataJpaTest or @SpringBootTest determines the type of test (Unit or Integration) or is it the use of @MockBean within the test that determines it?
2. Assuming that UserControllerTest.java is a Unit test we are mocking the userRepository dependency here with @MockBean private UserRepository userRepository whereas in UserRepositoryTest.java we are autowiring it with @Autowired private UserRepository userRepository. Why ??

Brandon :

The primary difference between unit tests and integration tests using Spring Boot, is that unit tests can run in isolation while integration tests will bootstrap Spring context before execution starts.

Running in isolation requires that you mock your dependencies based on the controller you are testing. By doing this, you're allowing yourself to test very specific test cases end-to-end without having to worry about the overhead of a database or a service. Hence, using the annotation @MockBean.

Whereas, integration testing focuses on integrating different layers of the application such as the database. Most people utilize an in memory database such as H2 to test their repositories. Integration tests should not contain any mocking and both types of testing should be run separately.

Resource: https://www.baeldung.com/spring-boot-testing