Mocking Spring bean's method behavior breaks aspects

Question

I searched SO and found bunch of other questions that looked similar but not exactly, so I'll ask another one.

I have Spring application and say I created custom aspect (looking for CatchMe annotation) to log exceptions in a specific way. I want to test the aspect by mocking the behavior of one of my Spring @Service class's method so it throws exception when it is called. Then in another method, annotated with my custom annotation @CatchMe, I call the first method. What I expect to happen is the exception to get logged. Unfortunatelly the exception is thrown but the aspect is not triggered. So how can I make the aspect to get triggered in this test using Mockito?

Note: I've checked those (plus a bunch more):

• Unit testing Spring @Around AOP methods
• Spring Aspect not triggered in unit test
• Spring: cannot inject a mock into class annotated with the @Aspect annotation

but most of them are Controller related and not Service related and I want to test only the service.

The Test

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = {BeanConfig.class})
public class MyServiceTest {

    @Autowired
    @InjectMocks
    private MyService service;

    @Mock
    private MyServiceDependency serviceDep;

    @Before
    public void setUp() throws Exception {
        MockitoAnnotations.initMocks(this);
        ReflectionTestUtils.setField(service, "serviceDep", serviceDep);
    }

    @Test
    public void test() {
        when(serviceDep.process()).thenAnswer(new Answer<Object>() {

                @Override
                public Object answer(InvocationOnMock invocationOnMock) throws Throwable {
                    throw new Exception("Sample message.");
                }

            });

        service.execute();
    }
}

Services

@Service
public class MyService {

    @Autowired
    private MyServiceDependency serviceDep;

    @CatchMe
    public void execute() {
        serviceDep.process();
    }
}


@Service
public class MyServiceDependency {

    public Object process() {
        // may throw exception here
    }
}

Configuration and Aspect

@Configuration
@EnableAspectJAutoProxy
@ComponentScan(basePackages = {"com.example.services"})
public class BeanConfig { .. }


@Aspect
@Component
public class CatchMeAspect {

    @Around("@annotation(CatchMe)")
    public Object catchMe(final ProceedingJoinPoint pjp) throws Throwable {
        try {
            pjp.proceed();
        } catch (Throwable t) {
            // fency log
        }

    }
}

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface CatchMe {}

EDIT: The functionality works but I want to verify it with the test.

Answer 1

Actually it is working as expected, however you are running in a side effect of proxy based AOP, especially class based proxies in this case.

Currently you are setting the field on the proxy and not on the actual object inside the proxy. Which is what you actually want. To obtain the actual instance use AopTestUtils.getUltimateTargetObject and then use that in the ReflectionTestUtils.setField method.

@Autowired
@InjectMocks
private MyService service;

@Mock
private MyServiceDependency serviceDep;

@Before
public void setUp() throws Exception {
    MockitoAnnotations.initMocks(this);
    MyService serviceToInject = AopTestUtils.getUltimateTargetObject(service);
    ReflectionTestUtils.setField(serviceToInject, "serviceDep", serviceDep);
}

However I think that approach is wrong, when you start messing around like this there is a better way. Simply use Spring to inject the mock. Create a specific @Configuration class for this test case. Make it a internal public static class and for the dependency add a mocked @Bean.

@Configuration
@Import(BeanConfig.class) 
public static class TestBeanConfig {

    @Bean
    public MyServiceDependency myServiceDependency() {
        return Mockito.mock(MyServiceDependency.class);
    }
}

Now in your test class you can simply @Autowire both beans and not need to use reflection or whatever to set dependencies.

@RunWith(SpringJUnit4ClassRunner.class)
public class MyServiceTest {

    @Autowired
    private MyService service;

    @Autowired
    private MyServiceDependency serviceDep;

    @Test
    public void test() {
        when(serviceDep.process()).thenAnswer(new Answer<Object>() {

                @Override
                public Object answer(InvocationOnMock invocationOnMock) throws Throwable {
                    throw new Exception("Sample message.");
                }

            });

        service.execute();
    }
}

Which will take care of the correct dependencies.

Answer 2

I had the same problem as @nyxz and this is intentional, see https://github.com/spring-projects/spring-boot/issues/7243.

Inspired by @M. Deinum following solution worked for me with Spring Boot 2.3.4.RELEASE and JUnit 5. We will just provide a mocked bean without @MockedBean

@SpringBootTest
@DirtiesContext(classMode = DirtiesContext.ClassMode.AFTER_EACH_TEST_METHOD)
class MyServiceTest {

    @Autowired
    private MyService service;

    @Test
    public void test() {
        service.execute();
    }

    static class TestBeanConfig {

         @Bean
         @Primary
         public MyServiceDependency myServiceDependency() {
             MyServiceDependency myServiceDependency = Mockito.mock(MyServiceDependency.class)
             // Add behavior of mocked bean here
             return myServiceDependency;
         }
    }
}