映射器定义中的可模仿spring依赖注入

Question

我需要从一个自定义映射方法访问一个Spring bean。但是在单元测试映射方法时，我还需要能够注入Spring bean的模拟。

下面是我的映射器类的一个最小示例：

@Mapper(componentModel = "spring")
public abstract class MyMapper {
    private final MyBean myBean;
    
    public MyMapper(MyBean myBean) {
        this.myBean = myBean;
    }

    @BeforeMapping
    protected MyElement initElement(MyElementDto dto) {
        // custom logic using the injected MyBean to initialize MyElement
    }
    
    public abstract MyElement map(MyElementDto dto);
}

@Component
public class MyMapperImpl extends MyMapper {
    @Autowired
    public MyMapperImpl(MyBean myBean) {
        super(myBean);
    }

    // ... mapping function implementation ...
}

因此，问题是：如何以最干净的方式实现这种类型的逻辑，以便生成的映射器实现是单元可测试的，并且可以正确地模拟MyBean依赖关系？

使用MapStruct 1.3.0、Final、Spring 4.3.25、Release、Mockito 1.9.5和Junit 4.12。

Answer 1

通过使用@objectfactory而不是@beforemapping进行元素初始化，找到了这种情况的解决方案。这也带来了更好的代码结构、关注点分离和可测试性。

元素初始化逻辑将在单独的Spring bean中定义：

@Component
public class MyFactory {
    private final MyBean myBean;

    @Autowired
    public MyFactory(MyBean myBean) {
        this.myBean = myBean;
    }

    @ObjectFactory
    public MyElement initialize(MyElementDto dto) {
        // custom logic using the injected MyBean to initialize MyElement
    }
}

上面的组件可以单独测试，模拟和注入MyBean。

@Mapper(componentModel = "spring",
        uses = MyFactory.class,
        injectionStrategy = InjectionStrategy.CONSTRUCTOR)
public interface MyMapper {
    MyElement map(MyElementDto dto);
}

/** THIS IS AUTOMATICALLY GENERATED CODE **/
@Component
public class MyMapperImpl implements MyMapper {
    private final MyFactory myFactory;

    @Autowired
    public MyMapperImpl(MyFactory myFactory) {
        this.myFactory = myFactory;
    }

    @Override
    public MyElement map(MyElementDto dto) {
        if ( dto == null ) {
            return null;
        }

        MyElement myElement = myFactory.initialize( dto ); // <-- FACTORY USED HERE

        // ... field mapping code here, after initialization ...

        return myElement;
    }
}

通过模拟和注入MyFactory，映射器很容易进行单元测试。我想避免加载任何Spring上下文，所以我手动初始化了MyFactoryImpl实例。

@RunWith(MockitoJUnitRunner.class)
public class MyMapperTest {
    @Mock
    private MyFactory myFactory;
    
    private MyMapper myMapper;
    
    @Before
    public void setUp() {
        // ... myFactory stubs ...
        
        myMapper = new MyMapperImpl(myFactory);
    }
    
    // ... tests ...
}