### Question:
PlaylistViewModel extends BaseViewModel { public void addVideosToPlaylist(List<Integer> videoIds, int playlistId){ playlistItemRepository.addVideoToPlayList(videoIds, 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 addVideoToPlaylists_callsTheRepoWithExactParameters(){ List<Integer> videoIds = new ArrayList<>(); playlistViewModel.addVideosToPlaylist(videoIds, 1); verify(playlistItemRepository, times(1)).addVideoToPlayList(videoIds, 1); }