Add back missing test scene

osu.Game.Tests/Visual/Online/TestSceneChatOverlay.cs

@@ -0,0 +1,44 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using osu.Framework.Allocation;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Game.Online.Chat;
+using osu.Game.Overlays;
+using osu.Game.Overlays.Chat;
+using osu.Game.Overlays.Chat.Tabs;
+
+namespace osu.Game.Tests.Visual.Online
+{
+    [Description("Testing chat api and overlay")]
+    public class TestSceneChatOverlay : OsuTestScene
+    {
+        public override IReadOnlyList<Type> RequiredTypes => new[]
+        {
+            typeof(ChatLine),
+            typeof(DrawableChannel),
+            typeof(ChannelSelectorTabItem),
+            typeof(ChannelTabControl),
+            typeof(ChannelTabItem),
+            typeof(PrivateChannelTabItem),
+            typeof(TabCloseButton)
+        };
+
+        [Cached]
+        private readonly ChannelManager channelManager = new ChannelManager();
+
+        [BackgroundDependencyLoader]
+        private void load()
+        {
+            Children = new Drawable[]
+            {
+                channelManager,
+                new ChatOverlay { State = { Value = Visibility.Visible } }
+            };
+        }
+    }
+}