@Test public void lightService_delete() { String LIGHT_UUID = "myUuid"; when(lightRepository.delete(LIGHT_UUID)).thenReturn(Observable.just(null)); TestSubscriber<Void> tester = new TestSubscriber<>(); lightService.delete(LIGHT_UUID).subscribe(tester); verify(lightRepository).delete(LIGHT_UUID); tester.assertCompleted(); tester.assertNoErrors(); }