Injecting Mockito mocks into a Spring bean

Given:

@Service
public class MyService {
@Autowired
private MyDAO myDAO;

// etc
}

You can have the class that is being tested loaded via autowiring, mock the dependency with Mockito, and then use Spring's ReflectionTestUtils to inject the mock into the class being tested.

@ContextConfiguration(classes = { MvcConfiguration.class })
@RunWith(SpringJUnit4ClassRunner.class)
public class MyServiceTest {
@Autowired
private MyService myService;

private MyDAO myDAOMock;

@Before
public void before() {
myDAOMock = Mockito.mock(MyDAO.class);
ReflectionTestUtils.setField(myService, "myDAO", myDAOMock);
}

// etc
}

Please note that before Spring 4.3.1, this method won't work with services behind a proxy (annotated with `@Transactional`, or `Cacheable`, for example). This has been fixed by [SPR-14050][1].

For earlier versions, a solution is to unwrap the proxy, as described there:

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(which is what `ReflectionTestUtils.setField` does by default now)

[1]:

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