UseCase { public abstract Observable buildUseCase(String query); UseCase(GitHubService gitHubService, ThreadExecutor threadExecutor,
      PostExecutionThread postExecutionThread); GitHubService getGitHubService(); Subscription getSubscription(); abstract Observable buildUseCase(String query); @SuppressWarnings("unchecked") void execute(Subscriber useCaseSubscriber, String query); void unsubscribe();  }
@Test public void buildUseCaseShouldReturnObservable() throws Exception { Observable observable = useCase.buildUseCase(MockFactory.TEST_USERNAME); assertNotNull(observable); }