Merge pull request #3306 from AvaloniaUI/fixes/double-detach-window-issue

Fix Exception when window is closed via Close() Method

Author: danwalmsley

src/Avalonia.Controls/Window.cs

@@ -336,7 +336,6 @@ internal void Close(bool ignoreCancel)
                 if (close)
                 {
                     PlatformImpl?.Dispose();
-                    HandleClosed();
                 }
             }
         }

tests/Avalonia.Controls.UnitTests/WindowTests.cs

@@ -228,8 +228,7 @@ public void Calling_Show_On_Closed_Window_Should_Throw()
         {
             using (UnitTestApplication.Start(TestServices.StyledWindow))
             {
-                var windowImpl = Mock.Of<IWindowImpl>(x => x.Scaling == 1);
-                var target = new Window(windowImpl);
+                var target = new Window();
 
                 target.Show();
                 target.Close();

tests/Avalonia.UnitTests/MockWindowingPlatform.cs

@@ -28,6 +28,10 @@ public static Mock<IWindowImpl> CreateWindowMock(Func<IPopupImpl> popupImpl = nu
                 return CreatePopupMock().Object;
 
             });
+            mock.Setup(x => x.Dispose()).Callback(() =>
+            {
+                mock.Object.Closed?.Invoke();
+            });
             PixelPoint pos = default;
             mock.SetupGet(x => x.Position).Returns(() => pos);
             mock.Setup(x => x.Move(It.IsAny<PixelPoint>())).Callback(new Action<PixelPoint>(np => pos = np));