Injecting Mockito mocks into a Spring bean

Question

I would like to inject a Mockito mock object into a Spring (3+) bean for the purposes of unit testing with JUnit. My bean dependencies are currently injected by using the

Answer 1

If you're using Spring Boot 1.4, it has an awesome way of doing this. Just use new brand @SpringBootTest on your class and @MockBean on the field and Spring Boot will create a mock of this type and it will inject it into the context (instead of injecting the original one):

@RunWith(SpringRunner.class)
@SpringBootTest
public class MyTests {

    @MockBean
    private RemoteService remoteService;

    @Autowired
    private Reverser reverser;

    @Test
    public void exampleTest() {
        // RemoteService has been injected into the reverser bean
        given(this.remoteService.someCall()).willReturn("mock");
        String reverse = reverser.reverseSomeCall();
        assertThat(reverse).isEqualTo("kcom");
    }

}

On the other hand, if you're not using Spring Boot or are you using a previous version, you'll have to do a bit more work:

Create a @Configuration bean that injects your mocks into Spring context:

@Configuration
@Profile("useMocks")
public class MockConfigurer {

    @Bean
    @Primary
    public MyBean myBeanSpy() {
        return mock(MyBean.class);
    }
}

Using @Primary annotation you're telling spring that this bean has priority if no qualifier are specified.

Make sure you annotate the class with @Profile("useMocks") in order to control which classes will use the mock and which ones will use the real bean.

Finally, in your test, activate userMocks profile:

@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = {Application.class})
@WebIntegrationTest
@ActiveProfiles(profiles={"useMocks"})
public class YourIntegrationTestIT {

    @Inject
    private MyBean myBean; //It will be the mock!


    @Test
    public void test() {
        ....
    }
}

If you don't want to use the mock but the real bean, just don't activate useMocks profile:

@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = {Application.class})
@WebIntegrationTest
public class AnotherIntegrationTestIT {

    @Inject
    private MyBean myBean; //It will be the real implementation!


    @Test
    public void test() {
        ....
    }
}