[FIXED] How to mock a method inside a method I'm testing?

Issue

I have a class RequestProcessor with a method:

   public ResponseClass process(Request request) {
       String requestId = requestService.saveRequest(request);
       ResponseClass response = new Response();
       response.setId(requestId);
       return response;
}

I need to write a test using Mockito, I came up with:

public class RequestProcessor {
    @InjectMocks
    private RequestProcess sut;
    @Mock
    private RequestService requestService;

    @Test
    public void test() {
    String requestId = UUID.randomUUID().toString();
    
    Request request = new Request(); //then setting up values of request
    Mockito.when(requestService.saveRequest(request).thenReturn(requestId);
    ResponseClass response = sut.process(request);
    Assert.assertEquals(response.getRequestId(), requestId)
}

But the response.getRequestId() return null. What is the problem?

Solution

This might be due to a missing mock behaviour of sut.process(request). Can you add the mock behaviour of sut.process(request) too?

public class RequestProcessor {
    @InjectMocks
    private RequestProcess sut;
    @Mock
    private RequestService requestService;

    @Test
    public void test() {
    String requestId = UUID.randomUUID().toString();
    
    Request request = new Request(); //then setting up values of request
    Mockito.when(requestService.saveRequest(request).thenReturn(requestId);
    Mockito.when(sut.process(request).thenCallRealMethod();
    ResponseClass response = sut.process(request);
    Assert.assertEquals(response.getRequestId(), requestId)
}

Answered By - Annamalai Palanikumar
Answer Checked By - Mary Flores (JavaFixing Volunteer)