Keep the queried item's media source as the playback default

tests/Jellyfin.Api.Tests/Helpers/MediaInfoHelperTests.cs

@@ -0,0 +1,99 @@
+using System;
+using System.Globalization;
+using Jellyfin.Api.Helpers;
+using MediaBrowser.Common.Net;
+using MediaBrowser.Controller.Configuration;
+using MediaBrowser.Controller.Devices;
+using MediaBrowser.Controller.Library;
+using MediaBrowser.Controller.MediaEncoding;
+using MediaBrowser.Model.Dto;
+using MediaBrowser.Model.MediaInfo;
+using Microsoft.Extensions.Logging;
+using Moq;
+using Xunit;
+
+namespace Jellyfin.Api.Tests.Helpers
+{
+    public class MediaInfoHelperTests
+    {
+        private static MediaInfoHelper CreateHelper()
+        {
+            return new MediaInfoHelper(
+                Mock.Of<IUserManager>(),
+                Mock.Of<ILibraryManager>(),
+                Mock.Of<IMediaSourceManager>(),
+                Mock.Of<IMediaEncoder>(),
+                Mock.Of<IServerConfigurationManager>(),
+                Mock.Of<ILogger<MediaInfoHelper>>(),
+                Mock.Of<INetworkManager>(),
+                Mock.Of<IDeviceManager>());
+        }
+
+        private static MediaSourceInfo CreateSource(Guid itemId, int bitrate, bool supportsDirectPlay = true)
+        {
+            return new MediaSourceInfo
+            {
+                Id = itemId.ToString("N", CultureInfo.InvariantCulture),
+                Protocol = MediaProtocol.File,
+                Bitrate = bitrate,
+                SupportsDirectPlay = supportsDirectPlay,
+                SupportsDirectStream = true,
+                SupportsTranscoding = true
+            };
+        }
+
+        [Fact]
+        public void SortMediaSources_PreferredItemExceedsBitrate_StaysDefault()
+        {
+            // The version the user was watching (the queried item) must stay the default
+            // even when a sibling version fits the bitrate limit better, since the resume
+            // position belongs to that exact version.
+            var preferredItemId = Guid.NewGuid();
+            var preferredSource = CreateSource(preferredItemId, bitrate: 80_000_000, supportsDirectPlay: false);
+            var siblingSource = CreateSource(Guid.NewGuid(), bitrate: 8_000_000);
+
+            var result = new PlaybackInfoResponse
+            {
+                MediaSources = [siblingSource, preferredSource]
+            };
+
+            CreateHelper().SortMediaSources(result, maxBitrate: 20_000_000, preferredItemId);
+
+            Assert.Equal(preferredSource.Id, result.MediaSources[0].Id);
+        }
+
+        [Fact]
+        public void SortMediaSources_NoPreferredItem_OrdersByPlayability()
+        {
+            var directPlay = CreateSource(Guid.NewGuid(), bitrate: 8_000_000);
+            var transcodeOnly = CreateSource(Guid.NewGuid(), bitrate: 8_000_000, supportsDirectPlay: false);
+            transcodeOnly.SupportsDirectStream = false;
+
+            var result = new PlaybackInfoResponse
+            {
+                MediaSources = [transcodeOnly, directPlay]
+            };
+
+            CreateHelper().SortMediaSources(result, maxBitrate: 20_000_000);
+
+            Assert.Equal(directPlay.Id, result.MediaSources[0].Id);
+        }
+
+        [Fact]
+        public void SortMediaSources_PreferredIdNotInSources_KeepsPlayabilityOrder()
+        {
+            var directPlay = CreateSource(Guid.NewGuid(), bitrate: 8_000_000);
+            var transcodeOnly = CreateSource(Guid.NewGuid(), bitrate: 8_000_000, supportsDirectPlay: false);
+            transcodeOnly.SupportsDirectStream = false;
+
+            var result = new PlaybackInfoResponse
+            {
+                MediaSources = [transcodeOnly, directPlay]
+            };
+
+            CreateHelper().SortMediaSources(result, maxBitrate: 20_000_000, Guid.NewGuid());
+
+            Assert.Equal(directPlay.Id, result.MediaSources[0].Id);
+        }
+    }
+}