Move HuesTestScene and runner to separate class files

hues.Game.Tests/HuesTestScene.cs

@@ -0,0 +1,9 @@
+using osu.Framework.Testing;
+
+namespace hues.Game.Tests
+{
+    public class HuesTestScene : TestScene
+    {
+        protected override ITestSceneTestRunner CreateRunner() => new HuesTestSceneTestRunner();
+    }
+}

hues.Game.Tests/HuesTestSceneTestRunner.cs

@@ -0,0 +1,17 @@
+using osu.Framework.Testing;
+
+namespace hues.Game.Tests
+{
+    public class HuesTestSceneTestRunner : HuesGameBase, ITestSceneTestRunner
+    {
+        private TestSceneTestRunner.TestRunner runner;
+
+        protected override void LoadAsyncComplete()
+        {
+            base.LoadAsyncComplete();
+            Add(runner = new TestSceneTestRunner.TestRunner());
+        }
+
+        public void RunTestBlocking(TestScene test) => runner.RunTestBlocking(test);
+    }
+}