使用 Mockito 进行单元测试时的空指针

Question

我正在为我的应用程序创建一个 Spring Boot API。 我正在尝试使用 mockito 对我的服务实现进行单元测试来模拟细节。 该服务将向数据库添加一个新的建筑实体。 下面是服务实现和测试实现。 建筑服务：

@Slf4j
@Service
public class BuildingServiceImpl implements BuildingService {

private BuildingRepository buildingRepository;
private BuildingRequestToEntityMapper buildingRequestToEntityMapper;

public BuildingServiceImpl(BuildingRepository buildingRepository, BuildingRequestToEntityMapper 
buildingRequestToEntityMapper){
this.buildingRepository=buildingRepository;
this.buildingRequestToEntityMapper=buildingRequestToEntityMapper;
}

public HttpStatus addBuilding(BuildingRequest buildingRequest){
    log.info("Inside addBuilding() service");
    BuildingEntity buildingEntity = buildingRequestToEntityMapper.map(buildingRequest);
    buildingRepository.save(buildingEntity);
    log.info("Building saved "+ buildingEntity);
    return HttpStatus.CREATED;
}

BuildingServiceImpl_UT

@RunWith(MockitoJUnitRunner.class)
public class BuildingServiceImpl_UT {

@Mock
BuildingRequestToEntityMapper buildingRequestToEntityMapper;

@Mock
BuildingRepository buildingRepository;

@InjectMocks
BuildingServiceImpl buildingServiceImpl;

@Test
public void buildingService_MapsRequest_AndSaveEntity(){
BuildingRequest buildingRequest = BuildingRequest.builder()
            .name("TestName")
            .telephone("4444444444")
            .postcode("TEst")
            .address("testAddress").build();

   when(buildingServiceImpl.addBuilding(any(BuildingRequest.class))).thenReturn(HttpStatus.CREATED);
    when(buildingRepository.save(any(BuildingEntity.class))).thenReturn(new BuildingEntity());

    buildingServiceImpl.addBuilding(buildingRequest);
    verify(buildingRepository, times(1)).save(any());
}

我已经模拟了映射器和存储库并将它们注入到服务中，但是当我运行测试时，我在测试类中的第一个 when().thenReturn() 语句中得到一个空指针异常。 请任何帮助。 谢谢

Answer 1

我不明白你的第一个 when().thenReturn()！ 您尝试在buildingServiceImpl上执行此操作，这不是模拟！ 此外，这毫无意义，因为您想测试此方法！ 我认为您应该为模拟buildingRequestToEntityMapper定义 when().thenReturn() ，但在您的实现中，您不需要为buildingRequestToEntityMapper.map()定义返回。 在这种情况下，变量buildingEntity将具有值null ，它应该在您的测试用例中工作。

@RunWith(MockitoJUnitRunner.class)
public class BuildingServiceImpl_UT {

@Mock
BuildingRequestToEntityMapper buildingRequestToEntityMapper;

@Mock
BuildingRepository buildingRepository;

@InjectMocks
BuildingServiceImpl buildingServiceImpl;

    @Test
    public void buildingService_MapsRequest_AndSaveEntity(){
    BuildingRequest buildingRequest = BuildingRequest.builder()
                .name("TestName")
                .telephone("4444444444")
                .postcode("TEst")
                .address("testAddress").build();


        when(buildingRepository.save(any(BuildingEntity.class))).thenReturn(new BuildingEntity());

        buildingServiceImpl.addBuilding(buildingRequest);
        verify(buildingRepository, times(1)).save(any());
        verify(buildingRequestToEntityMapper).map(any());
    }

Answer 2

这个：

when(buildingServiceImpl.addBuilding(any(BuildingRequest.class))).thenReturn(HttpStatus.CREATED);

不是必须的，你想测试方法： addBuilding不是模拟它。