有没有办法用嵌套的 Mapper 对 Mapstruct 进行单元测试？答案

【问题标题】：Is there any way to unit test a Mapstruct with nested Mapper?有没有办法用嵌套的 Mapper 对 Mapstruct 进行单元测试？
【发布时间】：2022-01-24 10:27:32
【问题描述】：

我正在尝试对 Mapstruct 嵌套映射器进行单元测试，如下所示：

@Mapper(componentModel = "spring", uses = EventCategoryMapper.class, injectionStrategy = InjectionStrategy.CONSTRUCTOR)
public interface EventMapper {

    
    Event fromEventMO(EventMO eventMO);

    EventMO toEventMO(Event event);

    default Optional<Event> fromOptionalEventMO(Optional<EventMO> optionalEventMO) {
        
        return (optionalEventMO.isEmpty()) ? Optional.empty() : Optional.of(fromEventMO(optionalEventMO.get()));
        
    }
    
}

@Mapper(componentModel = "spring", injectionStrategy = InjectionStrategy.CONSTRUCTOR)
public interface EventCategoryMapper {

    
    EventCategory fromEventCategoryMO(EventCategoryMO eventCategoryMO);

    EventCategoryMO toEventCategoryMO(EventCategory eventCategory);

    default String fromPriorityMO(PriorityMO priority) {
        return (priority.getPriority()==null) ? null : priority.getPriority();
    }

我正在尝试测试 EventMapper：

@ExtendWith(SpringExtension.class)
@ContextConfiguration(classes = {EventMapper.class, EventCategoryMapper.class, EventMapperImpl.class, EventCategoryMapperImpl.class})
public class EventMapperTest {

    private Mocks mocks; //This object contains the mocked objects that should be mapped.

    @Autowired
    private EventMapper eventMapper;

    @Test
    @DisplayName("Should return an Event from an EventMO")
    void shouldReturnEventfromEventMO() {
        
        var event = eventMapper.fromEventMO(mocks.getEventMO());

        assertEquals(event.getId(), 123L);


    }

但它总是失败：

创建名为“eventMapper”的 bean 时出错：bean 的实例化失败的;嵌套异常是 org.springframework.beans.BeanInstantiationException：失败实例化 [com.mycompany.cna.projects.fishmarket.back.events.repositories.mappers.event.EventMapper]：指定的类是一个接口

我已经尝试使用 Mapper.getMapper(EventMapper.class) 实例化映射器，它返回了 NullPointerException。

我应该怎么做才能对这类映射器进行单元测试？

【问题讨论】：

标签： java spring spring-boot unit-testing mapstruct

【解决方案1】：

我已经解决了这个问题。问题是我没有实例化我的 Mocks 对象。我还在 before 方法中为 EventMapperImpl 提供了嵌套映射器的模拟：

    @ExtendWith(SpringExtension.class)
public class EventMapperTest {

    private Mocks mocks;

    private EventMapper eventMapper;

    @Mock
    private EventCategoryMapper eventCategoryMapper;

    @BeforeEach
    void before() {
        eventMapper = new EventMapperImpl(eventCategoryMapper);
        mocks = new Mocks();
    }
    
    @Test
    @DisplayName("Should return an Event from an EventMO")
    void shouldReturnEventfromEventMO() {

        when(eventCategoryMapper.fromEventCategoryMO(any(EventCategoryMO.class))).thenReturn(mocks.getEventCategory());
        var event = eventMapper.fromEventMO(mocks.getEventMO());

        assertEquals(event.getId(), 123L);


    }

【讨论】：