1 files changed, 99 insertions, 0 deletions
diff --git a/tests/Jellyfin.Server.Implementations.Tests/Users/DisplayPreferencesManagerFailedWriteTests.cs b/tests/Jellyfin.Server.Implementations.Tests/Users/DisplayPreferencesManagerFailedWriteTests.cs
new file mode 100644
index 0000000000..13688c7574
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+++ b/tests/Jellyfin.Server.Implementations.Tests/Users/DisplayPreferencesManagerFailedWriteTests.cs
@@ -0,0 +1,99 @@
+using System;
+using System.Collections.Generic;
+using System.Data.Common;
+using Jellyfin.Server.Implementations.Tests.Item;
+using Jellyfin.Server.Implementations.Users;
+using Microsoft.Data.Sqlite;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Diagnostics;
+using Xunit;
+
+namespace Jellyfin.Server.Implementations.Tests.Users;
+
+public sealed class DisplayPreferencesManagerFailedWriteTests : SqliteDbTestFixture
+{
+    private const string Client = "client";
+
+    private static readonly Guid _userId = Guid.Parse("aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa");
+    private static readonly Guid _itemId = Guid.Parse("bbbbbbbb-bbbb-bbbb-bbbb-bbbbbbbbbbbb");
+
+    private readonly StatementInterceptor _statements;
+    private readonly DisplayPreferencesManager _manager;
+
+    public DisplayPreferencesManagerFailedWriteTests()
+        : this(new StatementInterceptor())
+    {
+    }
+
+    private DisplayPreferencesManagerFailedWriteTests(StatementInterceptor statements)
+        : base(statements)
+    {
+        _statements = statements;
+        _manager = new DisplayPreferencesManager(CreateDbContextFactory());
+    }
+
+    [Fact]
+    public void SetCustomItemDisplayPreferences_InsertFails_KeepsThePreviousPreferences()
+    {
+        _manager.SetCustomItemDisplayPreferences(_userId, _itemId, Client, new Dictionary<string, string?> { ["first"] = "1" });
+
+        _statements.FailInserts = true;
+        Assert.Throws<DbUpdateException>(() => _manager.SetCustomItemDisplayPreferences(_userId, _itemId, Client, new Dictionary<string, string?> { ["second"] = "2" }));
+
+        Assert.Equal(
+            new Dictionary<string, string?> { ["first"] = "1" },
+            _manager.ListCustomItemDisplayPreferences(_userId, _itemId, Client));
+    }
+
+    [Fact]
+    public void SetCustomItemDisplayPreferences_AnotherRequestStoredAKeyAfterTheDelete_StoresThePreferencesItWasGiven()
+    {
+        _manager.SetCustomItemDisplayPreferences(_userId, _itemId, Client, new Dictionary<string, string?> { ["first"] = "1" });
+
+        // The delete misses the row, as it does when another request stores it after this one's delete, so the unique
+        // index rejects this request's insert.
+        _statements.SkipNextDelete = true;
+        _manager.SetCustomItemDisplayPreferences(_userId, _itemId, Client, new Dictionary<string, string?> { ["first"] = "2" });
+
+        Assert.Equal(
+            new Dictionary<string, string?> { ["first"] = "2" },
+            _manager.ListCustomItemDisplayPreferences(_userId, _itemId, Client));
+    }
+
+    /// <summary>
+    /// Fails inserts into CustomItemDisplayPreferences with the error SQLite reports when the unique index rejects a row, or
+    /// leaves out the next delete from it.
+    /// </summary>
+    private sealed class StatementInterceptor : DbCommandInterceptor
+    {
+        public bool FailInserts { get; set; }
+
+        public bool SkipNextDelete { get; set; }
+
+        public override InterceptionResult<DbDataReader> ReaderExecuting(DbCommand command, CommandEventData eventData, InterceptionResult<DbDataReader> result)
+        {
+            FailInsert(command);
+            return result;
+        }
+
+        public override InterceptionResult<int> NonQueryExecuting(DbCommand command, CommandEventData eventData, InterceptionResult<int> result)
+        {
+            if (SkipNextDelete && command.CommandText.StartsWith("DELETE FROM \"CustomItemDisplayPreferences\"", StringComparison.Ordinal))
+            {
+                SkipNextDelete = false;
+                return InterceptionResult<int>.SuppressWithResult(0);
+            }
+
+            FailInsert(command);
+            return result;
+        }
+
+        private void FailInsert(DbCommand command)
+        {
+            if (FailInserts && command.CommandText.StartsWith("INSERT INTO \"CustomItemDisplayPreferences\"", StringComparison.Ordinal))
+            {
+                throw new SqliteException("SQLite Error 19: 'UNIQUE constraint failed: CustomItemDisplayPreferences.UserId, CustomItemDisplayPreferences.ItemId, CustomItemDisplayPreferences.Client, CustomItemDisplayPreferences.Key'.", 19);
+            }
+        }
+    }
+}