### Question:
PlaylistViewModel extends BaseViewModel { public void deletePlayList(int playlistId){ playlistRepository.deletePlayList(playlistId) .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe(); } @Inject  PlaylistViewModel(PlaylistRepository playlistRepository, PlaylistItemRepository playlistItemRepository); List<Integer> getVideoIdsToAdd(); void setVideoIdsToAdd(List<Integer> videoIdsToAdd); LiveData<List<Playlist>> getPlaylists(); void addPlayList(String title); void addVideosToPlaylist(List<Integer> videoIds, int playlistId); void deletePlayList(int playlistId);  }### Answer:
@Test public void deletePlaylists_callsTheRepositoryOnce() { playlistViewModel.deletePlayList(2); verify(playlistRepository, times(1)).deletePlayList(2); }