MapStruct not working in service class while running Test cases

Question

I am creating test cases, in one of my service class method I am using mapStruct to map entity into dto class.

This is my mapper class

@Mapper(componentModel = "spring")
public interface UserMapper {
    
    List<UserDto> toUserDto(List<UserEntity> users);
    }

below is how I am injecting in my service class

@Service
@RequiredArgsConstructor
public class UserServiceImpl implements UserService{

    private final UserMapper userMapper;

This is how I am using it

List<UserDto> userDto = userMapper.toUserDto(lst);

this is how I am doing it in my Test class

@RunWith(MockitoJUnitRunner.class)
@SpringBootTest(classes = Application.class)

public class ApplicationTest {
    
    @Mock
    private UserRepository userRepo;
    
    @Mock
    private UserMapper userMapper;
    
    
    @InjectMocks
    private UserServiceImpl userServiceImpl;
    
    @Test
    public void contextLoads() {
        then(controller).isNotNull();
        then(userServiceImpl).isNotNull();
    }
    
    @Test
    public void getAllUser() {
        List<UserEntity> lst = new ArrayList<UserEntity>();
        UserEntity userOne = new UserEntity();
        userOne.setEmpFullname("Test Test1");
        userOne.setUserId("marina");
        userOne.setFlag("Y");
        UserEntity usertwo = new UserEntity();
        usertwo.setEmpFullname("Test Test2");
        usertwo.setUserId("test");
        usertwo.setFlag("Y");
        lst.add(userOne);
        lst.add(usertwo);
        
        when(userRepo.findByStatus("W")).thenReturn(lst);
        try {
            List<UserDto> pendingUsersList = userServiceImpl.getPendingUser();
            assertEquals(2, pendingUsersList.size());
            
        } catch (GeneralException e) {
            e.printStackTrace();
        }   
    }
}

when I am running my test cases I am able to see these 2 records in entity class but when this line executes

List<UserDto> userDto = userMapper.toUserDto(lst); it gives me blank array.

Note - In my entity Class I have many fields but from test class I am passing only 3 parameters.

Answer 1

You have annotated your UserMapper with a @Mock annotation, without writing the mockito configuration for this mock. Then the blank array is expected. Remove the @Mock annotation, or specify what should be returned by the mock.
For example :

@RunWith(MockitoJUnitRunner.class)
@SpringBootTest(classes = Application.class)

public class ApplicationTest {
    
    @Mock
    private UserRepository userRepo;
    
    @Spy
    private UserMapper userMapper = Mappers.getMapper(UserMapper.class);
    
    
    @InjectMocks
    private UserServiceImpl userServiceImpl;