Add test scene for demonstrating OsuDropdown appearance

osu.Game.Tests/Visual/UserInterface/TestSceneOsuDropdown.cs

@@ -0,0 +1,20 @@
+// 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.Beatmaps;
+using osu.Game.Graphics.UserInterface;
+
+namespace osu.Game.Tests.Visual.UserInterface
+{
+    public class TestSceneOsuDropdown : ThemeComparisonTestScene
+    {
+        protected override Drawable CreateContent() =>
+            new OsuEnumDropdown<BeatmapSetOnlineStatus>
+            {
+                Anchor = Anchor.Centre,
+                Origin = Anchor.Centre,
+                Width = 150
+            };
+    }
+}

osu.Game.Tests/Visual/UserInterface/ThemeComparisonTestScene.cs

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+// 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.Linq;
+using NUnit.Framework;
+using osu.Framework.Allocation;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Shapes;
+using osu.Game.Graphics;
+using osu.Game.Overlays;
+
+namespace osu.Game.Tests.Visual.UserInterface
+{
+    public abstract class ThemeComparisonTestScene : OsuGridTestScene
+    {
+        protected ThemeComparisonTestScene()
+            : base(1, 2)
+        {
+        }
+
+        [BackgroundDependencyLoader]
+        private void load(OsuColour colours)
+        {
+            Cell(0, 0).AddRange(new[]
+            {
+                new Box
+                {
+                    RelativeSizeAxes = Axes.Both,
+                    Colour = colours.GreySeafoam
+                },
+                CreateContent()
+            });
+        }
+
+        private void createThemedContent(OverlayColourScheme colourScheme)
+        {
+            var colourProvider = new OverlayColourProvider(colourScheme);
+
+            Cell(0, 1).Clear();
+            Cell(0, 1).Add(new DependencyProvidingContainer
+            {
+                RelativeSizeAxes = Axes.Both,
+                CachedDependencies = new (Type, object)[]
+                {
+                    (typeof(OverlayColourProvider), colourProvider)
+                },
+                Children = new[]
+                {
+                    new Box
+                    {
+                        RelativeSizeAxes = Axes.Both,
+                        Colour = colourProvider.Background4
+                    },
+                    CreateContent()
+                }
+            });
+        }
+
+        protected abstract Drawable CreateContent();
+
+        [Test]
+        public void TestAllColourSchemes()
+        {
+            foreach (var scheme in Enum.GetValues(typeof(OverlayColourScheme)).Cast<OverlayColourScheme>())
+                AddStep($"set {scheme} scheme", () => createThemedContent(scheme));
+        }
+    }
+}