public void DownloadAndSaveAsTempFile_WithNullYoutubeVideo_ThrowsArgumentNullException()
 {
   IStateNotifier stateNotifier = new IStateNotifierMock();
   Downloader target = new Downloader(stateNotifier);
   YoutubeVideo youTubeVideo = null;
   
   target.DownloadAndSaveAsTempFile(youTubeVideo);
 }