public void UseRepositoryWhenPlaylistIsDeleted()
        {
            // arrange
            var userId       = UserId.Parse("12345");
            var playlistId   = PlaylistId.Parse("100");
            var playlistName = "playlistName";

            var mockedPlaylistRepository = PlaylistRepositoryBuilder.Create();

            mockedPlaylistRepository.Playlists.Add((userId, playlistId, playlistName));
            var playlistRepository = mockedPlaylistRepository.Build();
            var playlistHandler    = new PlaylistHandler(playlistRepository);

            // act
            playlistHandler.Handle(new PlaylistDeleted(userId, playlistId, playlistName));
            // assert
            Assert.AreEqual(0, mockedPlaylistRepository.Playlists.Count);
        }
        public void UseRepositoryWhenPlaylistIsAdded()
        {
            // arrange
            var userId       = UserId.Parse("12345");
            var playlistId   = PlaylistId.Parse("100");
            var playlistName = "playlistName";

            var mockedPlaylistRepository = PlaylistRepositoryBuilder.Create();
            var playlistRepository       = mockedPlaylistRepository.Build();
            var playlistHandler          = new PlaylistHandler(playlistRepository);

            // act
            playlistHandler.Handle(new PlaylistAdded(userId, playlistId, playlistName));
            // assert
            var(actualUserId, actualPlaylisId, actualPlaylistName) = mockedPlaylistRepository.Playlists.First();
            Assert.AreEqual(userId, actualUserId);
            Assert.AreEqual(playlistId, actualPlaylisId);
            Assert.AreEqual(playlistName, actualPlaylistName);
        }