How to disable Spring autowiring in unit tests for @Configuration/@Bean usage

Question

I want configure a component test using spring-test configuration inner class (@Configuration). Tested components has some services which I'd like to mock for the test. These services are classes (no interface used) and have spring annotations (@Autowired) in them. Mockito can easily mock them, however, I found no way of disabling spring autowiring.

Example how I can easily reproduce:

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = SomeTest.Beans.class)
public class SomeTest {

    // configured in component-config.xml, using ThirdPartyService
    @Autowired
    private TestedBean entryPoint;

    @Test
    public void test() {
    }

    @Configuration
    @ImportResource("/spring/component-config.xml")
    static class Beans {
        @Bean
        ThirdPartyService createThirdPartyService() {
            return mock(ThirdPartyService.class);
        }
    }
}

public class ThirdPartyService {
    @Autowired
    Foo bar;
}

public class TestedBean {
    @Autowired
    private ThirdPartyService service;
}

In this example "TestBean" represents the service to be mocked. I would NOT like "bar" to be injected by spring! @Bean(autowire = NO) does not help (in fact, that's the default value). (Please save me from "use interfaces!" comments - the mocked service can be 3rd party which I can't do anything with.)

UPDATE

Springockito partially solves the problem, as long as you don't have to have anything else to configure (so you can't use configuration class with Springockito - it does not support it), but use mocks only. Still looking for pure spring solution, if there's any...

Answer 1

Here is my solution to your problem:

import static org.mockito.Mockito.mockingDetails;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessorAdapter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class MockitoSkipAutowireConfiguration {

@Bean MockBeanFactory mockBeanFactory() {
    return new MockBeanFactory();
}

private static class MockBeanFactory extends InstantiationAwareBeanPostProcessorAdapter {
    @Override
    public boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException {
        return !mockingDetails(bean).isMock();
    }
}

} 

and then just

@Import(MockitoSkipAutowireConfiguration.class)

in your test @Configuration and you are all set

Answer 2

I solved it by creating FactoryBean for my bean instead of just mocking bean. At this way Spring don't try to autowire fields.

Factory bean helping class:

public class MockitoFactoryBean<T> implements FactoryBean<T> {
    private final Class<T> clazz;

    public MockitoFactoryBean(Class<T> clazz) {
        this.clazz = clazz;
    }

    @Override public T getObject() throws Exception {
        return mock(clazz);
    }

    @Override public Class<T> getObjectType() {
        return clazz;
    }

    @Override public boolean isSingleton() {
        return true;
    }
}

Actual test context part:

@Configuration
public class TestContext {

    @Bean
    public FactoryBean<MockingService> mockingService() {
        return new MockitoFactoryBean<>(MockingService.class);
    }
}

Answer 3

Check Spring profiles. You don't need to disable auto wiring, you need to inject different beans for different configuration.

Answer 4

I am in quite the same situation.

What I found that if you do not set the context loader by @ContextConfiguration annotation on your test class, the default context loader will be used, which derived from AbstractGenericContextLoader. I had a look at its source and turned out it registers all the bean post processors which are responsible for reading annotations such @Autowired. In other words, annotation config is enabled by default.

So the main problem is that there are two configurations which are in conflict: in the java config we said that autowiring is not needed, while the autowired annotation tells the opposite. The real question is how to disable the annotation processing in order to eliminate the undesired configuration.

As far as I know there is no such spring implementation of ContextLoader which would not be derived from AbstractGenericContextLoader so I guess the only we can do is to write our own. It would be something like this:

public static class SimpleContextLoader implements ContextLoader {

    @Override
    public String[] processLocations(Class<?> type, String... locations) {
        return strings;
    }

    @Override
    public ApplicationContext loadContext(String... locations) throws Exception {
        // in case of xml configuration
        return new ClassPathXmlApplicationContext(strings);
        // in case of java configuration (but its name is quite misleading)
        // return new AnnotationConfigApplicationContext(TestConfig.class);
    }

}

Of course it would be worth to spend more time to find out how to implement ContextLoader properly.

Cheers,
Robert

Answer 5

You could add the mocked service manually to the spring application context via org.springframework.beans.factory.config.SingletonBeanRegistry#registerSingleton. This way the mock is not post-processed by spring and spring does not attempt to autowire the mock. The mock itself will be injected into your tested bean.

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = SomeTest.Beans.class)
public class SomeTest {

    // configured in component-config.xml, using ThirdPartyService
    @Autowired
    private TestedBean entryPoint;

    @Autowired
    private ThirdPartyService thirdPartyServiceMock;

    @Test
    public void test() {
    }

    @Configuration
    static class Beans {

        @Autowired
        private GenericApplicationContext ctx;

        @Bean
        TestedBean testedBean() {
            ctx.getBeanFactory().registerSingleton("thirdPartyService", mock(ThirdPartyService.class));
            return new TestedBean();
        }
    }

    public static class ThirdPartyService {
        @Autowired
        Object bar;
    }

    public static class TestedBean {
        @Autowired
        private ThirdPartyService service;

    }
}

Answer 6

There are so many ways of doing this, I'm pretty sure that this answer will be incomplete, but here are a few options...

As currently seems to be recommended practice, use constructor injection for your services rather than autowiring the fields directly. This makes testing like this so much easier.

public class SomeTest {

    @Mock
    private ThirdPartyService mockedBean;

    @Before
    public void init() {
        initMocks(this);
    }

    @Test
    public void test() {
        BeanUnderTest bean = new BeanUnderTest(mockedBean);
        // ...
    }

}

public class BeanUnderTest{
    private ThirdPartyService service;
    @Autowired
    public BeanUnderTest(ThirdPartyService ThirdPartyService) {
        this.thirdPartyService = thirdPartyService;
    }
}

By doing that, you can also mix up autowired and mocked services by autowiring into the test itself and then constructing the beans under test with the most useful mix of autowired and mocked beans.

A reasonable alternative is to use Spring profiles to define stub services. This is particularly useful when wish to use the same stubbed features in multiple tests:

@Service
@Primary
@Profile("test")
public class MyServiceStub implements MyService {
    // ...
}

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = SomeTest.Beans.class) 
@ActiveProfiles({"test"})
public class SomeTest {
    // ...
}

By using the @Primary annotation, it ensures that this stub bean will be used instead of any other bean implementing the MyService interface. I tend to use this approach for things like email services, where by changing profile, I'm able to switch between a real mail server and Wiser.