Add unit test for the #2892 fix. (#2956)

UnitTests/Views/MenuTests.cs

@@ -2758,5 +2758,20 @@ wo
 			Assert.True (menu.ProcessHotKey (new KeyEvent (menu.Key, new KeyModifiers ())));
 			Assert.False (menu.IsMenuOpen);
 		}
+
+		[Fact]
+		public void Separators_Does_Not_Throws_Pressing_Menu_Shortcut ()
+		{
+			var menu = new MenuBar (new MenuBarItem [] {
+				new MenuBarItem ("File", new MenuItem [] {
+					new MenuItem ("_New", "", null),
+					null,
+					new MenuItem ("_Quit", "", null)
+				})
+			});
+
+			var exception = Record.Exception (() => Assert.True (menu.ProcessHotKey (new KeyEvent (Key.AltMask | Key.Q, new KeyModifiers () { Alt = true }))));
+			Assert.Null (exception);
+		}
 	}
 }