Add stress test of EventHandler

Fixes #138

Tests/EventTargetStressTests.cs

@@ -0,0 +1,69 @@
+using System;
+
+#if NUNIT
+using NUnit.Framework;
+using TestClassAttribute = NUnit.Framework.TestFixtureAttribute;
+using TestMethodAttribute = NUnit.Framework.TestCaseAttribute;
+#else
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+#endif
+
+using Ooui;
+using System.Linq;
+using System.Threading.Tasks;
+using System.Diagnostics;
+
+namespace Tests
+{
+    [TestClass]
+    public class EventTargetStressTests
+    {
+        [TestMethod]
+        public void LotsOfThreads ()
+        {
+            var input = new Input ();
+            Parallel.ForEach (Enumerable.Range (0, 100), _ => StressTestInput (input));
+        }
+
+        void StressTestInput (Input input)
+        {
+            var div = new Div (input);
+
+            var changeCount = 0;
+            var clickCount = 0;
+
+            void Input_Change (object sender, TargetEventArgs e)
+            {
+                changeCount++;
+            }
+            void Div_MessageSent (Message m)
+            {
+                if (m.Key == "click")
+                    clickCount++;
+            }
+
+            input.Change += Input_Change;
+            div.MessageSent += Div_MessageSent;
+
+            var sw = new Stopwatch ();
+            sw.Start ();
+            while (sw.ElapsedMilliseconds < 1000) {
+
+                var t = sw.Elapsed.ToString ();
+                input.Receive (Message.Event (input.Id, "change", t));
+
+                var b = new Button ("Click");
+                input.AppendChild (b);
+                b.Send (Message.Event (b.Id, "click"));
+                input.RemoveChild (b);
+            }
+
+            input.Change -= Input_Change;
+            div.RemoveChild (input);
+            div.MessageSent -= Div_MessageSent;
+
+            Assert.IsTrue (changeCount > 0);
+            Assert.IsTrue (clickCount > 0);
+        }
+    }
+}