Coalesce alternate-version progress onto primary in resume filter

1 files changed, 44 insertions, 0 deletions

diff --git a/tests/Jellyfin.Controller.Tests/Library/VersionResumeDataTests.cs b/tests/Jellyfin.Controller.Tests/Library/VersionResumeDataTests.cs
new file mode 100644
index 0000000000..5b0f003019
--- /dev/null
+++ b/tests/Jellyfin.Controller.Tests/Library/VersionResumeDataTests.cs
@@ -0,0 +1,44 @@
+using System;
+using MediaBrowser.Controller.Entities;
+using MediaBrowser.Controller.Library;
+using MediaBrowser.Model.Dto;
+using Xunit;
+
+namespace Jellyfin.Controller.Tests.Library;
+
+public class VersionResumeDataTests
+{
+    [Fact]
+    public void ApplyTo_OverridesResumeFieldsAndPercentage()
+    {
+        var lastPlayed = new DateTime(2026, 1, 2, 0, 0, 0, DateTimeKind.Utc);
+        var resume = new VersionResumeData(
+            new UserItemData { Key = "version", PlaybackPositionTicks = 25, Played = true, LastPlayedDate = lastPlayed },
+            RunTimeTicks: 100);
+
+        var dto = new UserItemDataDto { Key = "primary", PlaybackPositionTicks = 1, Played = false, PlayedPercentage = 1 };
+
+        resume.ApplyTo(dto);
+
+        Assert.Equal(25, dto.PlaybackPositionTicks);
+        Assert.True(dto.Played);
+        Assert.Equal(lastPlayed, dto.LastPlayedDate);
+
+        // The percentage is based on the resume version's own runtime, not the primary's.
+        Assert.NotNull(dto.PlayedPercentage);
+        Assert.Equal(25.0, dto.PlayedPercentage.Value, 5);
+    }
+
+    [Fact]
+    public void ApplyTo_WithoutRuntime_LeavesPercentageUntouched()
+    {
+        var resume = new VersionResumeData(new UserItemData { Key = "version", PlaybackPositionTicks = 25 }, null);
+        var dto = new UserItemDataDto { Key = "primary", PlayedPercentage = 42 };
+
+        resume.ApplyTo(dto);
+
+        Assert.Equal(25, dto.PlaybackPositionTicks);
+        Assert.NotNull(dto.PlayedPercentage);
+        Assert.Equal(42.0, dto.PlayedPercentage.Value, 5);
+    }
+}