Override a single @Configuration class on every spring boot @Test

Inner test configuration

Example of an inner @Configuration for your test:

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

    @Configuration
    static class ContextConfiguration {
        @Bean
        @Primary //may omit this if this is the only SomeBean defined/visible
        public SomeBean someBean () {
            return new SomeBean();
        }
    }

    @Autowired
    private SomeBean someBean;

    @Test
    public void testMethod() {
        // test
    }
}

Reusable test configuration

If you wish to reuse the Test Configuration for multiple tests, you may define a standalone Configuration class with a Spring Profile @Profile("test"). Then, have your test class activate the profile with @ActiveProfiles("test"). See complete code:

@RunWith(SpringRunner.class)
@SpringBootTests
@ActiveProfiles("test")
public class SomeTest {

    @Autowired
    private SomeBean someBean;

    @Test
    public void testMethod() {
        // test
    }
}

@Configuration
@Profile("test")
public class TestConfiguration {
    @Bean
    @Primary //may omit this if this is the only SomeBean defined/visible
    public SomeBean someBean() {
        return new SomeBean();
    }
}

@Primary

The @Primary annotation on the bean definition is to ensure that this one will have priority if more than one are found.