Add benchmark runner.

osu.Game.Benchmarks/BenchmarkTest.cs

@@ -0,0 +1,23 @@
+// 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 BenchmarkDotNet.Attributes;
+using BenchmarkDotNet.Running;
+using NUnit.Framework;
+
+namespace osu.Game.Benchmarks
+{
+    [TestFixture]
+    [MemoryDiagnoser]
+    public abstract class BenchmarkTest
+    {
+        [GlobalSetup]
+        [OneTimeSetUp]
+        public virtual void SetUp()
+        {
+        }
+
+        [Test]
+        public void RunBenchmark() => BenchmarkRunner.Run(GetType());
+    }
+}