Merge pull request #20 from nventive/dev/dera/lockedMemoized

Adding a thread-safe memoized func

src/Uno.Core.Tests/FuncsFixture.cs

@@ -0,0 +1,53 @@
+// ******************************************************************
+// Copyright � 2015-2018 nventive inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// ******************************************************************
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Uno.Extensions;
+
+namespace Uno.Core.Tests
+{
+	[TestClass]
+	public class FuncsFixture
+	{
+#if DEBUG
+		private const TestTimeout _timeout = TestTimeout.Infinite;
+#else
+		private const int _timeout = 5000;
+#endif
+
+		[TestMethod]
+		[Timeout(_timeout)]
+		public async Task When_AsLockedMemoized_ThenSameInstance()
+		{
+			var mre = new ManualResetEvent(false);
+
+			Func<object> myFunc = () => { mre.WaitOne(); return new object(); };
+			var asLockedMemoized = myFunc.AsLockedMemoized();
+
+			var a = Task.Run(asLockedMemoized);
+			var b = Task.Run(asLockedMemoized);
+
+			mre.Set();
+
+			await Task.WhenAll(a, b);
+
+			Assert.IsTrue(object.ReferenceEquals(a.Result, b.Result));
+		}
+	}
+}