public async Task GetPlayListsAsyncShouldReturnPlayLists()
{
//arrange
PlayList playList = new PlayList();
_mixBLMock.Setup(i => i.GetPlayListsAsync());
PlayListController playListController = new PlayListController(_mixBLMock.Object);
//act
var result = await playListController.GetPlayListsAsync();
//assert
Assert.IsType <OkObjectResult>(result);
}