source: class CountCitiesInteractorTest {
  
      @Test
      public void applyWithProgressingAsFalseThenUpdateCitiesCount() {
  
target: 
          BehaviorSubject<Boolean> progressing = BehaviorSubject.createDefault(false);
          BehaviorSubject<Integer> citiesCount = BehaviorSubject.create();
  
          new CountCitiesInteractor(progressing, citiesCount).apply(Flowable.just(10));
  
          assertEquals(Integer.valueOf(10), citiesCount.getValue());
  
      }
  
  }