Mockito InjectMocks字段无法注入其他InjectMocks字段的解决办法

今天写单元测试用例，跑起来后，出现了空指针异常。于是查了下，发现Mock对象的一个属性未注入，为null。我的程序结构大致为：

@Repository
public class MyRepository {

    public void doSomething() {
        System.out.println("here's dosomething");
    }

    public Model findById(Long id) {
        return new Model(id, "Real Repository");
    }
}

@Service
public class MyService {

    @Autowired
    private MyRepository myRepository;

    public void doSomething() {
        this.myRepository.doSomething();
    }

    public Model findById(Long id) {
        return this.myRepository.findById(id);
    }
}

@Controller
public class MyController {

    @Autowired
    private MyService myService;

    public void doSomething() {
        this.myService.doSomething();
    }

    public Model findById(Long id) {
        return this.myService.findById(id);
    }
}

@RunWith(MockitoJUnitRunner.class)
public class MyControllerTest {

    @Mock
    private MyRepository myRepository;

    @InjectMocks
    private MyService myService;

    @InjectMocks
    private MyController myController;

    @Before
    public void setUp() throws Exception {
        Model model = new Model(11L, "AAA");
        doNothing().when(myRepository).doSomething();
        when(myRepository.findById(11L)).thenReturn(model);
    }

    @Test
    public void doSomething() throws Exception {
        this.myController.doSomething();
    }

    @Test
    public void findById() throws Exception {
        System.out.println(this.myController.findById(11L));
    }
}

使用Mock打桩的为MyRepository，原本以为使用InjectMocks后，MyService会自动注入MyRepository，MyController会自动注入前的MyService，但是结果并不是这样的。MyController认不到MyService。MyController实例后，没有给myService属性赋值。看起来InjectMocks只能使用Mock注解的。于是想在 MyService上加个Mock，虽然编译没问题，但是运行起来异常了：

org.mockito.exceptions.base.MockitoException: This combination of annotations is not permitted on a single field:
@Mock and @InjectMocks

于是只能另寻他路，考虑到使用Spring来做容器管理，修改Test类：

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"classpath:beans.xml"})
public class MyControllerTest {

    @Mock
    private MyRepository myRepository;

    @InjectMocks
    @Autowired
    private MyService myService;

    @Autowired
    private MyController myController;

    @Before
    public void setUp() throws Exception {
        MockitoAnnotations.initMocks(this);
        Model model = new Model(11L, "AAA");
        doNothing().when(myRepository).doSomething();
        when(myRepository.findById(11L)).thenReturn(model);
    }

    @Test
    public void doSomething() throws Exception {
        this.myController.doSomething();
    }

    @Test
    public void findById() throws Exception {
        System.out.println(this.myController.findById(11L));
    }
}

果然可以了，模拟了数据库访问：

@autowire加哪里还有讲究，必须2个都加，否则也会出现注入不到的情况。

既然没法注入，其实不借助容器，也可以手动来赋值。在setup方法中做下修改，便得到方法二：

@RunWith(MockitoJUnitRunner.class)
public class MyControllerTest {

    @Mock
    private MyRepository myRepository;

    @InjectMocks
    private MyService myService;

    @InjectMocks
    private MyController myController;

    @Before
    public void setUp() throws Exception {
        ReflectionTestUtils.setField(myController, "myService", myService);
        Model model = new Model(11L, "AAA");
        doNothing().when(myRepository).doSomething();
        when(myRepository.findById(11L)).thenReturn(model);
    }

    @Test
    public void doSomething() throws Exception {
        this.myController.doSomething();
    }

    @Test
    public void findById() throws Exception {
        System.out.println(this.myController.findById(11L));
    }
}

执行效果是一样的，如上图。

两种方法都能满足多级的注入情形。如果不想依赖Spring，可以选择用第2种的方式。