@Test
  public void lightService_update() {
    LightModel lightModel = new LightModel();

    when(lightRepository.update(lightModel)).thenReturn(Observable.just(null));

    TestSubscriber<Void> tester = new TestSubscriber<>();
    lightService.update(lightModel).subscribe(tester);

    verify(lightRepository).update(lightModel);

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