added Responder unit tests

UnitTests/ResponderTests.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Terminal.Gui;
+using Xunit;
+
+// Alais Console to MockConsole so we don't accidentally use Console
+using Console = Terminal.Gui.MockConsole;
+
+namespace Terminal.Gui {
+	public class ResponderTests {
+		[Fact]
+		public void TestNew ()
+		{
+			var r = new Responder ();
+			Assert.NotNull (r);
+			Assert.Equal ("Terminal.Gui.Responder", r.ToString ());
+			Assert.False (r.CanFocus);
+			Assert.False (r.HasFocus);
+		}
+
+		[Fact]
+		public void TestMethods ()
+		{
+			var r = new Responder ();
+
+			Assert.False (r.ProcessKey (new KeyEvent () { Key = Key.Unknown }));
+			Assert.False (r.ProcessHotKey (new KeyEvent () { Key = Key.Unknown }));
+			Assert.False (r.ProcessColdKey (new KeyEvent () { Key = Key.Unknown }));
+			Assert.False (r.OnKeyDown (new KeyEvent () { Key = Key.Unknown }));
+			Assert.False (r.OnKeyUp (new KeyEvent () { Key = Key.Unknown }));
+			Assert.False (r.MouseEvent (new MouseEvent () { Flags = MouseFlags.AllEvents }));
+			Assert.False (r.OnMouseEnter (new MouseEvent () { Flags = MouseFlags.AllEvents }));
+			Assert.False (r.OnMouseLeave (new MouseEvent () { Flags = MouseFlags.AllEvents }));
+			Assert.False (r.OnEnter ());
+			Assert.False (r.OnLeave ());
+		}
+	}
+}