Mock Repository From Controller class using Spring Boot and JUnit

Question

I am writing the test cases for my controller class which is a Spring Boot Application and I want to write the test cases only for controller class which invokes Service and Service to Repository. I am using SpringBootTest which is used for to create the instances for all of my beans. I want to mock only Database calls and external api calls.

MyController {

    @Autowired
    MyService service;

    //Api call for getDetails
    service.getDetails();
}


MyService {

   @Autowired
   MyRepository repo;

}

MyControllertest {
    @Autowired
    MyController controller;

    @Mock
    MyRepository repoMock;

    @Before
    public void setup(){
        // intit mocks
    }

    @Test
    public void myTest(){
        when(repoMock.getDetails()).thenReturn(null);
        controller.getdetails();
    }
}

When I run the test case, it is not using the mock Repository, instead of that using the @Autowired Repository which is mentioned in the Service class.

Can anyone please explain me how to mock the repository from controller class.

Posting so many questions in this blog, but am not getting any responses.

Answer 1

It is not using your Mocks because you are not injecting those mocks into your controller / service classes. Instead you are Autowiring it.
Correct way to do it is

@RunWith(MockitoJUnitRunner.class)
public class MyControllerTest {

    @InjectMocks
    MyController controller;
    .....

}

Even better solution would be to get rid of Field Injection and use Constructor Injection

For example in your Controller and Service class. Instead of using @Autowired on Fields you can do it on Contructor. For example

class MyService {

   private final MyRepository repo;

   @Autowired
   public MyService(final MyRepository repo) {
      this.repo = repo;
   }
}

Similarly in Controller class

class MyController {

    @Autowired
    private final MyService service;

    public MyController(final MyService service) {
         this.service = service
    }
}

Doing this way will help you in setting mocks easily during runtime. For example in your test class you could do

@RunWith(MockitoJUnitRunner.class)
public class MyControllertest {

    MyController controller;
    MyService service;

    @Mock
    MyRepository repoMock;


    @Before
    public void setup(){
        // init mocks
      service = new MyService(repoMock);
      controller = new MyController(service);
    }
  ..............
}

Here is a nice article about Field injection