Add failing test scene

osu.Game.Tests/Skins/TestSceneSkinProvidingContainer.cs

@@ -0,0 +1,92 @@
+// 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.Collections.Generic;
+using System.Linq;
+using NUnit.Framework;
+using osu.Framework.Audio.Sample;
+using osu.Framework.Bindables;
+using osu.Framework.Extensions.IEnumerableExtensions;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.OpenGL.Textures;
+using osu.Framework.Graphics.Textures;
+using osu.Game.Audio;
+using osu.Game.Skinning;
+using osu.Game.Tests.Visual;
+
+namespace osu.Game.Tests.Skins
+{
+    public class TestSceneSkinProvidingContainer : OsuTestScene
+    {
+        /// <summary>
+        /// Ensures that the first inserted skin after resetting (via source change)
+        /// is always prioritised over others when providing the same resource.
+        /// </summary>
+        [Test]
+        public void TestPriorityPreservation()
+        {
+            TestSkinProvidingContainer provider = null;
+            TestSkin mostPrioritisedSource = null;
+
+            AddStep("setup sources", () =>
+            {
+                var sources = new List<TestSkin>();
+                for (int i = 0; i < 10; i++)
+                    sources.Add(new TestSkin());
+
+                mostPrioritisedSource = sources.First();
+
+                Child = provider = new TestSkinProvidingContainer(sources);
+            });
+
+            AddAssert("texture provided by expected skin", () =>
+            {
+                return provider.FindProvider(s => s.GetTexture(TestSkin.TEXTURE_NAME) != null) == mostPrioritisedSource;
+            });
+
+            AddStep("trigger source change", () => provider.TriggerSourceChanged());
+
+            AddAssert("texture still provided by expected skin", () =>
+            {
+                return provider.FindProvider(s => s.GetTexture(TestSkin.TEXTURE_NAME) != null) == mostPrioritisedSource;
+            });
+        }
+
+        private class TestSkinProvidingContainer : SkinProvidingContainer
+        {
+            private readonly IEnumerable<ISkin> sources;
+
+            public TestSkinProvidingContainer(IEnumerable<ISkin> sources)
+            {
+                this.sources = sources;
+            }
+
+            public new void TriggerSourceChanged() => base.TriggerSourceChanged();
+
+            protected override void OnSourceChanged()
+            {
+                ResetSources();
+                sources.ForEach(AddSource);
+            }
+        }
+
+        private class TestSkin : ISkin
+        {
+            public const string TEXTURE_NAME = "virtual-texture";
+
+            public Drawable GetDrawableComponent(ISkinComponent component) => throw new System.NotImplementedException();
+
+            public Texture GetTexture(string componentName, WrapMode wrapModeS, WrapMode wrapModeT)
+            {
+                if (componentName == TEXTURE_NAME)
+                    return Texture.WhitePixel;
+
+                return null;
+            }
+
+            public ISample GetSample(ISampleInfo sampleInfo) => throw new System.NotImplementedException();
+
+            public IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup) => throw new System.NotImplementedException();
+        }
+    }
+}