ModelMapper使用JUnit Mockito抛出NPE

Question

我正在使用ModelMapper进行NPE

目录服务测试

@RunWith(SpringJUnit4ClassRunner.class)
@SpringBootTest
public class CatalogServiceTest {

    @Rule
    public ExpectedException thrown = ExpectedException.none();
    @InjectMocks private CatalogService service;
    @Mock ModelMapper modelMapper;
    @Mock CatalogMapper catalogMapper;
    @Mock CatalogRepository catalogRepository;


    @Before
    public void setUp() throws Exception {
//        MockitoAnnotations.initMocks(this);
        CatalogEntity catalogEntity = new CatalogEntity();
        catalogEntity.setId("id");
        catalogEntity.setCode("code");
        catalogEntity.setType("type");
        catalogEntity.setValue("value");

//        Optional<CatalogEntity> optionalCatalog = Optional.of(catalogEntity);
        when(catalogRepository.findByCode(any(String.class))).thenReturn(catalogEntity);
    }

    @Test
    public void whenFindByCode() {
        //Act
        CatalogDto myCatalogDto = service.findByCode("code");
        //Assert
        assertTrue(myCatalogDto.getCode().equals("code"));
    }
}

目录服务

@Service
public class CatalogService {

    private static final Logger LOGGER = LoggerFactory.getLogger(CatalogService.class);

    @Autowired
    CatalogRepository catalogRepository;

    @Autowired
    CatalogMapper catalogMapper;

    /**
     * 
     * @param type
     * @return catalog objects which type is type
     */
    public List<CatalogDto> findByType(String type) {
        LOGGER.info("Getting catalogs by type {}", type);
        List<CatalogEntity> catalogsEntityList = catalogRepository.findByType(type);
        List<CatalogDto> catalogDtoList = new ArrayList<>();
        catalogsEntityList.forEach(catalogEntity -> {
            catalogDtoList.add(catalogMapper.convertCatalogEntityToCatalogDto(catalogEntity));
        });
        return catalogDtoList;
    }
    
    /**
     * Find catalog by code.
     * @param code
     * @return catalog
     */
    public CatalogDto findByCode(String code) {
        LOGGER.info("Getting catalogs by code {}", code);
        return catalogMapper.convertCatalogEntityToCatalogDto(catalogRepository.findByCode(code));
    }
}

目录映射器

@Component
public class CatalogMapper {
    @Autowired
    private ModelMapper modelMapper;
    
    /**
     * Converts CatalogEntity object to CatalogDto object
     * @param catalogEntity
     * @return converted CatalogDto object
     */
    public CatalogDto convertCatalogEntityToCatalogDto(CatalogEntity catalogEntity) {
        return modelMapper.map(catalogEntity, CatalogDto.class);
    }
}

目录库

@Repository
public interface CatalogRepository extends MongoRepository<CatalogEntity, String> {

    List<CatalogEntity> findByType(String type);

    CatalogEntity findByCode(String code);
    
}

catalogRepository.findByCode（code）按预期返回CatalogEntity对象，问题出现在执行catalogMapper.convertCatalogEntityToCatalogDto（catalogRepository.findByCode（code））；返回null之后。

Answer 1

catalogMapper是一个没有存根方法的模拟。

有几种方法可以修复您的测试：

选项1：仅测试与CatalogMapper的交互

在该选项中，您将存根调用catalogMapper.convertCatalogEntityToCatalogDto。这是一个精简单元测试，您只测试与协作服务的交互。

正如您所说，您希望测试mapper的实际实现，有两个选项：

选项2：使用SpringBootTest

在这个选项中，您依赖SpringBootTest来设置整个应用程序上下文。

您需要进行以下更改：

• 使用@Autowired而不是@InjectMock使您的对象接受测试

@SpringBootTest
public class CatalogServiceTest {

    @Rule
    public ExpectedException thrown = ExpectedException.none();
    @Autowired
    private CatalogService service;
    @MockBean
    CatalogRepository catalogRepository;

}

选项3：构建您自己需要的服务

• 摆脱@SpringBootTest
• 仅模拟要模拟的对象-存储库
• 为其他服务创建真实对象
• 您可能需要将服务中的字段注入更改为构造函数注入，这是一个好主意

@Service
public class CatalogService {

    final CatalogRepository catalogRepository;

    final CatalogMapper catalogMapper;

    @Autowired
    public CatalogService(CatalogRepository catalogRepository, CatalogMapper catalogMapper) {
        this.catalogRepository = catalogRepository;
        this.catalogMapper = catalogMapper;
    }
}

这种方法只创建测试使用的对象，而不是整个应用程序上下文，因此可能会导致选项2所述的更精简的测试。

@RunWith(MockitoJUnitRunner.class)
public class CatalogServiceTest {

    @Rule
    public ExpectedException thrown = ExpectedException.none();

    private CatalogService service;
    @Mock
    CatalogRepository catalogRepository;


    @Before
    public void setUp() throws Exception {
        var modelMapper = new ModelMapper();
        var catalogMapper =new CatalogMapper(modelMapper);
        service = new CatalogService(catalogRepository, catalogMapper);

        CatalogEntity catalogEntity = new CatalogEntity();
        catalogEntity.setId("id");
        catalogEntity.setCode("code");
        when(catalogRepository.findByCode(any(String.class))).thenReturn(catalogEntity);
    }

}