1 files changed, 59 insertions, 0 deletions
diff --git a/tests/Jellyfin.Controller.Tests/Entities/AggregateFolderTests.cs b/tests/Jellyfin.Controller.Tests/Entities/AggregateFolderTests.cs
new file mode 100644
index 0000000000..6c297673d4
--- /dev/null
+++ b/tests/Jellyfin.Controller.Tests/Entities/AggregateFolderTests.cs
@@ -0,0 +1,59 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using MediaBrowser.Controller.Entities;
+using MediaBrowser.Controller.Library;
+using MediaBrowser.Controller.Persistence;
+using Moq;
+using Xunit;
+
+namespace Jellyfin.Controller.Tests.Entities;
+
+public class AggregateFolderTests
+{
+    [Fact]
+    public void Children_ClearedAfterALibraryWasAdded_ListsTheNewLibrary()
+    {
+        var existing = new Folder { Id = Guid.NewGuid(), Path = "/libraries/movies" };
+        var added = new Folder { Id = Guid.NewGuid(), Path = "/libraries/collections" };
+
+        // What the repository holds grows once the new library has been resolved and stored.
+        var stored = new List<BaseItem> { existing };
+
+        var itemRepository = new Mock<IItemRepository>();
+        itemRepository.Setup(x => x.GetItemList(It.IsAny<InternalItemsQuery>()))
+            .Returns(() => stored.ToList());
+
+        var libraryManager = new Mock<ILibraryManager>();
+        libraryManager.Setup(x => x.GetItemById(It.IsAny<Guid>()))
+            .Returns((Guid id) => stored.Find(i => i.Id.Equals(id)));
+
+        BaseItem.ItemRepository = itemRepository.Object;
+        BaseItem.LibraryManager = libraryManager.Object;
+
+        var root = new AggregateFolder { Id = Guid.NewGuid(), Path = "/libraries" };
+
+        Assert.Equal([existing.Id], root.Children.Select(i => i.Id));
+
+        stored.Add(added);
+        root.Children = null;
+
+        // Null-forgiving: the setter takes null to mean "drop the cache", the getter reloads.
+        Assert.Equal([existing.Id, added.Id], root.Children!.Select(i => i.Id));
+    }
+
+    [Fact]
+    public void Children_AssignedASet_KeepsThatSet()
+    {
+        var itemRepository = new Mock<IItemRepository>(MockBehavior.Strict);
+        BaseItem.ItemRepository = itemRepository.Object;
+
+        var assigned = new Folder { Id = Guid.NewGuid(), Path = "/libraries/movies" };
+        var root = new AggregateFolder { Id = Guid.NewGuid(), Path = "/libraries" };
+
+        root.Children = [assigned];
+
+        // Never goes to the repository, so the strict mock stays unused.
+        Assert.Equal([assigned.Id], root.Children.Select(i => i.Id));
+    }
+}