Add test coverage for song select footer area

osu.Game.Tests/Visual/SongSelect/TestSceneSongSelectFooter.cs

@@ -0,0 +1,35 @@
+// 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 osu.Framework.Graphics;
+using osu.Game.Screens.Select;
+
+namespace osu.Game.Tests.Visual.SongSelect
+{
+    public class TestSceneSongSelectFooter : OsuManualInputManagerTestScene
+    {
+        public TestSceneSongSelectFooter()
+        {
+            AddStep("Create footer", () =>
+            {
+                Footer footer;
+                AddRange(new Drawable[]
+                {
+                    footer = new Footer
+                    {
+                        Anchor = Anchor.Centre,
+                        Origin = Anchor.Centre,
+                    }
+                });
+
+                footer.AddButton(new FooterButtonMods(), null);
+                footer.AddButton(new FooterButtonRandom
+                {
+                    NextRandom = () => { },
+                    PreviousRandom = () => { },
+                }, null);
+                footer.AddButton(new FooterButtonOptions(), null);
+            });
+        }
+    }
+}