public async Task AddPlayListShouldAddPlayList()
{
var playList = new PlayList();
_mixBLMock.Setup(x => x.AddPlayListAsync(It.IsAny <PlayList>())).Returns(Task.FromResult <PlayList>(playList));
var playlistController = new PlayListController(_mixBLMock.Object);
var result = await playlistController.AddPlaylistAsync(new PlayList());
Assert.IsAssignableFrom <CreatedAtActionResult>(result);
_mixBLMock.Verify(x => x.AddPlayListAsync((It.IsAny <PlayList>())));
}