JUnit test to retrieve all entities fails with actual result '[]'

Question

I am trying to test my method for getting back all entities that exist in my db. I am using JUnit and Mockito. I have no experience with testing so far and this is how far I've got: This is my method from the agency service to get back all entities, using the findAll() function of JpaRepository:

      public List<AgencyDto> getAll() {
        return repo.findAll().stream().map(agency -> mapper.mapToDto(agency)).collect(Collectors.toList());
    }

@ExtendWith(MockitoExtension.class)
public class AgencyServiceTest {

    @Mock
    private AgencyRepository agencyRepository;


    @InjectMocks
    private AgencyService agencyService;

    @Test
    void getAgencies() {
        List<AgencyDto> agencies = new ArrayList<AgencyDto>();

        AgencyDto agency1 = new AgencyDto();
        AgencyDto agency2 = new AgencyDto();

        agency1.setName("agency");
        agency1.setEmail("agency@yahoo.com");

        agency2.setName("agencyy");
        agency2.setEmail("agencyy@yahoo.com");

        agencies.add(agency1);
        agencies.add(agency2);

        List<Agency> existingAgencies = new ArrayList<Agency>();

        existingAgencies.add(mapper.mapToEntity(agency1));
        existingAgencies.add(mapper.mapToEntity(agency2));

        when(agencyRepository.findAll()).thenReturn(existingAgencies);

        List<AgencyDto> result = agencyService.getAll();

        assertEquals(agencies, result);
    }
}

When running the test, the value for expected seems ok, but the value for actual is an empty array:

Expected :[com.project.DTOs.AgencyDto@245a26e1, com.project.DTOs.AgencyDto@4d63b624, com.project.DTOs.AgencyDto@466cf502]
Actual   :[]

Is this not the right way to test get() methods? Am I doing something wrong when setting the actual result?

Answer 1

Issue is here

  List<Agency> existingAgencies = new ArrayList<Agency>();
  when(agencyRepository.findAll()).thenReturn(existingAgencies);

your mock returns an empty list, you need to add items to list

eg:

List<Agency> existingAgencies = new ArrayList<Agency>();
existingAgencies.add(yourDTOObject1);
existingAgencies.add(yourDTOObject2);
existingAgencies.add(yourDTOObject3);
when(agencyRepository.findAll()).thenReturn(existingAgencies);
List<Agency> result = agencyRepository.findAll();
assertEquals(agencies, result);

---

Also you miss to mock agencyService.getAll()

I think you need to do something like when(agencyService.getAll()).thenReturn(agencies);