Add test coverage of editor sample playback

osu.Game.Tests/Visual/Editing/TestSceneEditorSamplePlayback.cs

@@ -0,0 +1,47 @@
+// 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.Linq;
+using NUnit.Framework;
+using osu.Framework.Graphics.Audio;
+using osu.Framework.Testing;
+using osu.Game.Rulesets;
+using osu.Game.Rulesets.Osu;
+using osu.Game.Rulesets.Osu.Objects.Drawables;
+
+namespace osu.Game.Tests.Visual.Editing
+{
+    public class TestSceneEditorSamplePlayback : EditorTestScene
+    {
+        protected override Ruleset CreateEditorRuleset() => new OsuRuleset();
+
+        [Test]
+        public void TestSlidingSampleStopsOnSeek()
+        {
+            DrawableSlider slider = null;
+            DrawableSample[] samples = null;
+
+            AddStep("get first slider", () =>
+            {
+                slider = Editor.ChildrenOfType<DrawableSlider>().OrderBy(s => s.HitObject.StartTime).First();
+                samples = slider.ChildrenOfType<DrawableSample>().ToArray();
+            });
+
+            AddStep("start playback", () => EditorClock.Start());
+
+            AddUntilStep("wait for slider sliding then seek", () =>
+            {
+                if (!slider.Tracking.Value)
+                    return false;
+
+                if (!samples.Any(s => s.Playing))
+                    return false;
+
+                EditorClock.Seek(20000);
+                return true;
+            });
+
+            AddAssert("slider samples are not playing", () => samples.Length == 5 && samples.All(s => s.Played && !s.Playing));
+        }
+    }
+}