Added view tests

src/HotUI/Controls/View.cs

@@ -55,7 +55,10 @@ namespace HotUI {
 				viewHandler?.SetView (this.GetRenderView());
 			}
 		}
-		internal void UpdateFromOldView (IViewHandler handler) => ViewHandler = handler;
+		internal void UpdateFromOldView (View view) {
+			ViewHandler = view.ViewHandler;
+			view.ViewHandler = null;
+		}
 		View builtView;
 		public View BuiltView => builtView;
 		void ResetView()

src/HotUI/Helpers/DatabindingExtensions.cs

@@ -135,7 +135,7 @@ namespace HotUI {
 				}
 			}
 
-			newView.UpdateFromOldView (oldView.ViewHandler);
+			newView.UpdateFromOldView (oldView);
 
 
 			return newView;

tests/HotUI.Tests/ViewTests.cs

@@ -0,0 +1,54 @@
+using System;
+using Xunit;
+
+namespace HotUI.Tests {
+	public class ViewTests {
+
+		public class StatePage : View {
+			public readonly State<int> clickCount = new State<int> (1);
+			public readonly State<string> text = new State<string> ();
+			public readonly State<bool> boolState = new State<bool> ();
+		}
+
+		[Fact]
+		public void RebuildingViewsReuseNativeView()
+		{
+			Text text = null;
+			Text currentText = null;
+			var view = new StatePage ();
+
+			view.text.Value = "Hello";
+			int buildCount = 0;
+
+			view.Body = () => {
+				buildCount++;
+				currentText = new Text ($"{view.text.Value} - {view.clickCount.Value}");
+				return currentText;
+			};
+
+			var viewHandler = new GenericViewHandler ();
+			view.ViewHandler = viewHandler;
+
+
+			text = currentText;
+			var textHandler = new GenericViewHandler ();
+			text.ViewHandler = textHandler;
+
+
+			Assert.Equal (1, buildCount);
+
+			view.clickCount.Value++;
+
+
+			Assert.Equal (2, buildCount);
+
+
+			//Check to make sure that the view was rebuilt
+			Assert.NotEqual (text,currentText);
+			//Make sure the old one is unasociated 
+			Assert.Null (text?.ViewHandler);
+			//Make sure the new view has the old handler
+			Assert.Equal (currentText?.ViewHandler, textHandler);
+		}
+	}
+}