Fixes #2156 - BREAKING CHANGE - Fixes IsOverridden and makes it internal

Terminal.Gui/Core/Responder.cs

@@ -16,6 +16,7 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Reflection;
 
 namespace Terminal.Gui {
 	/// <summary>
@@ -236,6 +237,25 @@ public virtual void OnEnabledChanged () { }
 		/// </summary>
 		public virtual void OnVisibleChanged () { }
 
+		/// <summary>
+		/// Utilty function to determine <paramref name="method"/> is overridden in the <paramref name="subclass"/>.
+		/// </summary>
+		/// <param name="subclass">The view.</param>
+		/// <param name="method">The method name.</param>
+		/// <returns><see langword="true"/> if it's overridden, <see langword="false"/> otherwise.</returns>
+		internal static bool IsOverridden (Responder subclass, string method)
+		{
+			MethodInfo m = subclass.GetType ().GetMethod (method,
+				BindingFlags.Instance
+				| BindingFlags.Public
+				| BindingFlags.NonPublic
+				| BindingFlags.DeclaredOnly);
+			if (m == null) {
+				return false;
+			}
+			return m.GetBaseDefinition ().DeclaringType != m.DeclaringType;
+		}
+
 		/// <summary>
 		/// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
 		/// </summary>

Terminal.Gui/Core/View.cs

@@ -3073,19 +3073,5 @@ public View GetTopSuperView ()
 
 			return top;
 		}
-
-		/// <summary>
-		/// Check if the <paramref name="method"/> is overridden in the <paramref name="view"/>.
-		/// </summary>
-		/// <param name="view">The view.</param>
-		/// <param name="method">The method name.</param>
-		/// <returns><see langword="true"/> if it's overridden, <see langword="false"/> otherwise.</returns>
-		public bool IsOverridden (View view, string method)
-		{
-			Type t = view.GetType ();
-			MethodInfo m = t.GetMethod (method);
-
-			return (m.DeclaringType == t || m.ReflectedType == t) && m.GetBaseDefinition ().DeclaringType == typeof (Responder);
-		}
 	}
 }

UnitTests/ResponderTests.cs

@@ -3,6 +3,7 @@
 using System.Linq;
 using Terminal.Gui;
 using Xunit;
+using static Terminal.Gui.Core.ViewTests;
 
 // Alias Console to MockConsole so we don't accidentally use Console
 using Console = Terminal.Gui.FakeConsole;
@@ -44,5 +45,52 @@ public void Dispose_Works ()
 		{
 
 		}
+
+		public class DerivedView : View {
+			public DerivedView ()
+			{
+			}
+
+			public override bool OnKeyDown (KeyEvent keyEvent)
+			{
+				return true;
+			}
+		}
+
+		[Fact]
+		public void IsOverridden_False_IfNotOverridden ()
+		{
+			// MouseEvent IS defined on Responder but NOT overridden
+			Assert.False (Responder.IsOverridden (new Responder () { }, "MouseEvent"));
+
+			// MouseEvent is defined on Responder and NOT overrident on View
+			Assert.False (Responder.IsOverridden (new View () { Text = "View does not override MouseEvent" }, "MouseEvent"));
+			Assert.False (Responder.IsOverridden (new DerivedView () { Text = "DerivedView does not override MouseEvent" }, "MouseEvent"));
+
+			// MouseEvent is NOT defined on DerivedView 
+			Assert.False (Responder.IsOverridden (new DerivedView () { Text = "DerivedView does not override MouseEvent" }, "MouseEvent"));
+
+			// OnKeyDown is defined on View and NOT overrident on Button
+			Assert.False (Responder.IsOverridden (new Button () { Text = "Button does not override OnKeyDown" }, "OnKeyDown"));
+		}
+
+		[Fact]
+		public void IsOverridden_True_IfOverridden ()
+		{
+			// MouseEvent is defined on Responder IS overriden on ScrollBarView (but not View)
+			Assert.True (Responder.IsOverridden (new ScrollBarView () { Text = "ScrollBarView overrides MouseEvent" }, "MouseEvent"));
+
+			// OnKeyDown is defined on View
+			Assert.True (Responder.IsOverridden (new View () { Text = "View overrides OnKeyDown" }, "OnKeyDown"));
+
+			// OnKeyDown is defined on DerivedView
+			Assert.True (Responder.IsOverridden (new DerivedView () { Text = "DerivedView overrides OnKeyDown" }, "OnKeyDown"));
+
+			// ScrollBarView overrides both MouseEvent (from Responder) and Redraw (from View)
+			Assert.True (Responder.IsOverridden (new ScrollBarView () { Text = "ScrollBarView overrides MouseEvent" }, "MouseEvent"));
+			Assert.True (Responder.IsOverridden (new ScrollBarView () { Text = "ScrollBarView overrides Redraw" }, "Redraw"));
+
+			Assert.True (Responder.IsOverridden (new Button () { Text = "Button overrides MouseEvent" }, "MouseEvent"));
+		}
 	}
 }