Spring boot 2.1 bean override vs. Primary

Question

With Spring Boot 2.1 bean overriding is disabled by default, which is a good thing.

However I do have some tests where I replace beans with mocked instances using Mo

Answer 1

It is allowed to override @Component with @Bean by default. In your case

@Service
public class AService {
}

@Component
public class BService {
    @Autowired
    public BService() { ... }
}

@Configuration
@ComponentScan
public BaseConfiguration {
}

@Configuration
// WARNING! Doesn't work with @SpringBootTest annotation
@Import({BaseConfiguration.class})
public class TestConfiguration {
    @Bean // you allowed to override @Component with @Bean.
    public BService bService() {
        return Mockito.mock(BService.class);
    }
}