JUnit 测试。使用ModelMapper库将实体转换为DTO时的问题

Question

我正在开发 Spring Boot Web 应用程序，并且有一个 ModelMapper 库的自定义实现，它允许我转换单个对象和对象列表。

@Component
public class ObjectMapperUtils {

@Autowired
private static ModelMapper modelMapper;

static {
    modelMapper = new ModelMapper();
    modelMapper.getConfiguration().setMatchingStrategy(MatchingStrategies.STRICT);
}

private ObjectMapperUtils() {
}

public <D, T> D map(final T entity, Class<D> outClass) {
    return modelMapper.map(entity, outClass);
}

public <D, T> List<D> mapAll(final Collection<T> entityList, Class<D> outCLass) {
    return entityList.stream().map(entity -> map(entity, outCLass)).collect(Collectors.toList());
}
}

在服务层，我有一个方法从 DB UserEntity 对象返回并将其转换为 UserDTO。

@Autowired
private UserRepository userRepository;

@Autowired
private ObjectMapperUtils modelMapper;

@Override
public UserDTO getByUserId(String userId) {
    UserEntity userEntity = userRepository.findByUserId(userId)
            .orElseThrow(() -> new NotFoundException("User with userId[" + userId + "] not found"));
    //UserDTO userDTO = new UserDTO();
    //BeanUtils.copyProperties(userEntity, userDTO);
    return modelMapper.map(userEntity, UserDTO.class); // userDTO;
}

当我尝试为此方法创建测试时出现问题。UserDTO 始终返回 NULL 值。

class UserServiceImplTest {

@InjectMocks
private UserServiceImpl userService;

@Mock
private UserRepository userRepository;

@Mock
private ObjectMapperUtils modelMapper;

@BeforeEach
void setUp() throws Exception {
    MockitoAnnotations.initMocks(this);
}

@Test
void testGetByUserId() {
    UserEntity userEntity = new UserEntity();
    userEntity.setId(1L);
    userEntity.setUsername("zavada");
    userEntity.setUserId("33b4c069-e907-45a9-8d49-2042044c56e0");

    when(userRepository.findByUserId(anyString()))
                 .thenReturn(Optional.of(userEntity));

    UserDTO userDTO = userService.getByUserId("33b4c069-e907-45a9-8d49-2042044c56e0");
    System.out.println(userDTO); <--- NULL

    assertEquals("zavada", userDTO.getUsername());
    assertNotNull(userDTO);

}
}

当我在 Service 层上使用 BeanUtils.copyProperties(obj1, obj2); 转换时 - 测试成功通过。使用 ModelMapper 我得到 NULL。有什么想法如何解决此错误或重构代码吗？提前致谢

Answer 1

要以 user268396 答案为基础，您需要以下内容才能使其正常工作：

@RunWith(MockitoJUnitRunner.class)
    public class StackOverflowTest {

        @InjectMocks
        private StackOverflow userService = new StackOverflow();

        @Mock
        private UserRepository userRepository;

        @Mock
        private ObjectMapperUtils modelMapper;
        private UserDTO userDTO = new UserDTO();
        private UserEntity userEntity = new UserEntity();

        @Before
        public void setUp() {
            when(modelMapper.map(any(), any())).thenReturn(userDTO);

            userDTO.setId(1L);
            userDTO.setUsername("zavada");
            userDTO.setUserId("33b4c069-e907-45a9-8d49-2042044c56e0");
        }

        @Test
        public void testGetByUserId() throws Throwable {
            when(userRepository.findByUserId(anyString())).thenReturn(Optional.of(userEntity));

            UserDTO result = userService.getByUserId("33b4c069-e907-45a9-8d49-2042044c56e0");
            System.out.println(result);

            assertEquals("zavada", result.getUsername());
            assertNotNull(result);

        }
    }

这是一个很容易犯的错误，重要的是要记住，您@mock编辑的所有对象都不再是真正的实现，如果您期望返回任何行为，则需要预先定义它。