Add the ability to solo a test in visual testing using [Solo] attribute

Author: peppy

osu.Framework/Testing/SoloAttribute.cs

@@ -0,0 +1,18 @@
+// 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 JetBrains.Annotations;
+
+namespace osu.Framework.Testing
+{
+    /// <summary>
+    /// Denotes a single test method which will be "solo"ed during visual execution.
+    /// This implies all other tests will be ignored.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Method)]
+    [MeansImplicitUse]
+    public class SoloAttribute : Attribute
+    {
+    }
+}

osu.Framework/Testing/TestBrowser.cs

@@ -400,7 +400,13 @@ private void finishLoad(TestScene newTest, Action onCompletion)
 
             bool hadTestAttributeTest = false;
 
-            foreach (var m in newTest.GetType().GetMethods())
+            var methods = newTest.GetType().GetMethods();
+
+            var solo = methods.FirstOrDefault(m => m.GetCustomAttribute(typeof(SoloAttribute), false) != null);
+            if (solo != null)
+                methods = new[] { solo };
+
+            foreach (var m in methods)
             {
                 string name = m.Name;