Overriding an Autowired Bean in Unit Tests

I had similar problem and I solved with a mix and I find this one more useful and reusable. I created a spring profile for the tests and a config class that overrides the beans I want to mock in a very simple way:

@Profile("test")
@Configuration
@Import(ApplicationConfiguration.class)
public class ConfigurationTests {

    @MockBean
    private Producer kafkaProducer;

    @MockBean
    private SlackNotifier slackNotifier;

}

By doing that I can @Autowire those mock beans and use mockito to verify on them. Main advantage is that now all tests seamlessly get the mock beans without any per-test change. Tested with:

spring boot 1.4.2

You should use spring profiles in order to know what kind of bean you want to use in different contexts.

http://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-profiles.html

In Spring Boot 1.4 there's a simple way for doing that:

@RunWith(SpringRunner.class)
@SpringBootTest(classes = { MyApplication.class })
public class MyTests {
    @MockBean
    private MyBeanClass myTestBean;

    @Before
    public void setup() {
         ...
         when(myTestBean.doSomething()).thenReturn(someResult);
    }

    @Test
    public void test() {
         // MyBeanClass bean is replaced with myTestBean in the ApplicationContext here
    }
}

If you just simply want to provide a different bean in your tests, i think you don't need to use spring profiles or mockito.

Just do the following:

@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = { TestConfig.class })
public class MyTest
{
    @Configuration
    @Import(Application.class) // the actual configuration
    public static class TestConfig
    {
        @Bean
        public IMyService myService()
        {
            return new MockedMyService();
        }
    }

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

NOTE: tested with spring boot 1.3.2 / spring 4.2.4