parent
      module-one
      module-two
      ...
      module-n

@Service
public void MegaService {
    @Autowired
    MegaRepository repository;
    // ....
}

public interface MegaRepository extends JpaRepository<MegaModel, Long> {
   // ...
}

@Configuration
public class TestRepoConfiguration {

    @Bean
    MegaRepository megaRepository(MegaRepository repository) {
        return Mockito.spy(repository); // of course, it does not work
    }
}

@RunWith(SpringJUnit4ClassRunner.class)
public class MegaIntegrationTest {
    @Autowired
    MegaRepository repository;

    public void testMegaLogic() {
        when(repository.findAll()).thenAnswer(invocation -> {
             System.out.println("Hello, comrades");
             return invocation;
        });
    }
}