Musify/backend/Tests/Musify.Application.Tests/Shared/TrackApplicationResponseTests.cs

using Musify.Application.Tests.TestSupport;
using Musify.Application.Tracks.Responses;
using Musify.Domain.Entities;
using Musify.Domain.ValueObjects;
using Xunit;

namespace Musify.Application.Tests.Shared
{
    public sealed class TrackApplicationResponseTests
    {
        [Fact]
        public void FromEntity_LocalTrack_UsesOwnerNameAsArtist()
        {
            var owner = TestEntities.User(1, "The Owner");
            var track = TestEntities.LocalTrack(owner);

            var response = TrackApplicationResponse.FromEntity(track, listensCount: 3);

            Assert.Equal("The Owner", response.Artist);
            Assert.Equal(TrackSource.Local, response.Source);
            Assert.Equal(owner.Id, response.OwnerUserId);
            Assert.Equal(3, response.ListensCount);
        }

        [Fact]
        public void FromEntity_ExternalTrackWithArtists_JoinsThemInPositionOrder()
        {
            var track = TestEntities.ExternalTrack();
            var second = new Artist { Name = "Second Artist", NormalizedName = "SECOND ARTIST", ExternalId = "second" };
            var first = new Artist { Name = "First Artist", NormalizedName = "FIRST ARTIST", ExternalId = "first" };
            track.TrackArtists =
            [
                new TrackArtist { TrackId = track.Id, ArtistId = second.Id, Position = 1, Artist = second, Track = track },
                new TrackArtist { TrackId = track.Id, ArtistId = first.Id, Position = 0, Artist = first, Track = track }
            ];

            var response = TrackApplicationResponse.FromEntity(track, listensCount: 0);

            Assert.Equal("First Artist, Second Artist", response.Artist);
            Assert.Equal(track.ExternalId, response.ExternalId);
        }

        [Fact]
        public void FromEntity_ExternalTrackWithNoArtists_HasNullArtist()
        {
            var track = TestEntities.ExternalTrack();

            var response = TrackApplicationResponse.FromEntity(track, listensCount: 0);

            Assert.Null(response.Artist);
        }
    }
}