@Test
  public void lightService_findByEnvironment() {
    Integer ENVIRONMENT = 108;
    List<LightModel> lights = new ArrayList<>();

    when(lightRepository.findByEnvironment(ENVIRONMENT)).thenReturn(Observable.just(lights));

    TestSubscriber<List<LightModel>> tester = new TestSubscriber<>();
    lightService.findByEnvironment(ENVIRONMENT).subscribe(tester);

    verify(lightRepository).findByEnvironment(ENVIRONMENT);

    tester.assertValue(lights);
    tester.assertCompleted();
    tester.assertNoErrors();
  }