test: add failing test case for issue 460.

tests/HeadlessTest.Ursa/Controls/UrsaWindowTests/UrsaWindowTest.cs

@@ -0,0 +1,44 @@
+using Avalonia.Headless.XUnit;
+using Ursa.Controls;
+
+namespace HeadlessTest.Ursa.Controls.UrsaWindowTests;
+
+public class UrsaWindowTest
+{
+    [AvaloniaFact]
+    public void Default_UrsaWindow_Closing_Is_Called_Once()
+    {
+        var ursaWindow = new UrsaWindow();
+        ursaWindow.Show();
+        int count = 0;
+        ursaWindow.Closing += (_, _) => count++;
+        ursaWindow.Close();
+        Assert.Equal(1, count);
+    }
+
+    [AvaloniaFact]
+    public async void Inferenced_Window_Closing_Called_Once_When_Yes()
+    {
+        var window = new UrsaWindowWithCloseInference();
+        window.Show();
+        int count = 0;
+        window.Closing += (_, _) => count++;
+        window.Close();
+        window.DialogViewModel.CloseYes();
+        Assert.Equal(1, count);
+    }
+
+    [AvaloniaFact]
+    public async void Inferenced_Window_Closing_Called_Once_When_No()
+    {
+        var window = new UrsaWindowWithCloseInference();
+        window.Show();
+        int count = 0;
+        window.Closing += (_, _) => count++;
+        window.Close();
+        window.DialogViewModel.Close();
+        Assert.Equal(1, count);
+    }
+    
+    
+}

tests/HeadlessTest.Ursa/Controls/UrsaWindowTests/UrsaWindowWithCloseInference.axaml

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+<u:UrsaWindow xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+        xmlns:u="https://irihi.tech/ursa"
+        mc:Ignorable="d" d:DesignWidth="800"
+        d:DesignHeight="450"
+        x:Class="HeadlessTest.Ursa.Controls.UrsaWindowTests.UrsaWindowWithCloseInference"
+        Title="UrsaWindowWithCloseInference">
+    Hello World
+</u:UrsaWindow>

tests/HeadlessTest.Ursa/Controls/UrsaWindowTests/UrsaWindowWithCloseInference.axaml.cs

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+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+using Avalonia.Markup.Xaml;
+using Irihi.Avalonia.Shared.Contracts;
+using Ursa.Controls;
+
+namespace HeadlessTest.Ursa.Controls.UrsaWindowTests;
+
+public partial class UrsaWindowWithCloseInference : UrsaWindow
+{
+    public UrsaWindowWithCloseInference()
+    {
+        InitializeComponent();
+    }
+    
+    internal TextBox TextBox = new TextBox();
+    internal DialogViewModel DialogViewModel = new DialogViewModel();
+
+    protected override async Task<bool> CanClose()
+    {
+        var result = await OverlayDialog.ShowModal(TextBox, DialogViewModel);
+        return result == DialogResult.Yes;
+    }
+}
+
+class DialogViewModel : IDialogContext
+{
+    public void Close()
+    {
+        RequestClose?.Invoke(this, DialogResult.No);
+    }
+    
+    public void CloseYes()
+    {
+        RequestClose?.Invoke(this, DialogResult.Yes);
+    }
+
+    public event EventHandler<object?>? RequestClose;
+}