Add Mediator for UI notifications

OpenRA.Test/OpenRA.Game/MediatorTest.cs

@@ -0,0 +1,44 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2022 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using NUnit.Framework;
+using OpenRA.Widgets;
+
+namespace OpenRA.Test
+{
+	[TestFixture]
+	public class MediatorTest
+	{
+		[TestCase(TestName = "Mediator test")]
+		public void Test()
+		{
+			var mediator = new Mediator();
+			var testHandler = new TestHandler();
+			mediator.Subscribe(testHandler);
+
+			mediator.Send(new TestNotificaton());
+
+			Assert.IsTrue(testHandler.WasNotified);
+		}
+	}
+
+	public class TestHandler : INotificationHandler<TestNotificaton>
+	{
+		public bool WasNotified { get; set; }
+
+		public void Handle(TestNotificaton notification)
+		{
+			WasNotified = true;
+		}
+	}
+
+	public class TestNotificaton { }
+}