public void Patch()
{
var totalSongsBefore = playlist.GetAll().Count();
var song = repository.Get(m => m.Id == 1);
song.Artist += totalSongsBefore;
var httpStatus = controller.Patch(song, 1);
var songAfter = repository.Get(m => m.Id == 1);
FailIfNull(m => controller.Patch(m, 1));
FailIfMissingFields(m => controller.Patch(m, 1));
FailIfNotFound(m => controller.Patch(song, m));
Assert.AreEqual(HttpStatusCode.OK, httpStatus.StatusCode);
Assert.AreEqual(song.Artist, songAfter.Artist);
}