Imported Upstream version 3.6.0

Former-commit-id: da6be194a6b1221998fc28233f2503bd61dd9d14

external/aspnetwebstack/test/Microsoft.Web.Mvc.Test/Controls/Test/MvcTestHelper.cs

@@ -0,0 +1,21 @@
+// Copyright (c) Microsoft Corporation. All rights reserved. See License.txt in the project root for license information.
+
+using System.IO;
+using System.Web.UI;
+
+namespace Microsoft.Web.Mvc.Controls.Test
+{
+    public static class MvcTestHelper
+    {
+        public static string GetControlRendering(Control c, bool designMode)
+        {
+            if (designMode)
+            {
+                c.Site = new DesignModeSite();
+            }
+            HtmlTextWriter writer = new HtmlTextWriter(new StringWriter());
+            c.RenderControl(writer);
+            return writer.InnerWriter.ToString();
+        }
+    }
+}