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。