Add comprehensive headless tests for 10 controls with enhanced ItemsSource and method testing (#18)

* Initial plan

* Add comprehensive tests for 5 controls: Avatar, Clock, ClockTicks, AspectRatioLayout, AspectRatioLayoutItem

Co-authored-by: rabbitism <14807942+rabbitism@users.noreply.github.com>

* Complete comprehensive headless tests for all 10 controls - added 72 more tests

Co-authored-by: rabbitism <14807942+rabbitism@users.noreply.github.com>

* Add requested test cases for MultiComboBox and TreeComboBox - ItemsSource, Remove, Clear, hierarchical data

Co-authored-by: rabbitism <14807942+rabbitism@users.noreply.github.com>

* test: open dropdown to trigger materialization.

* test: set CurrentCulture to en-US for calendar view tests

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: rabbitism <14807942+rabbitism@users.noreply.github.com>
Co-authored-by: rabbitism <dongbin@irihi.tech>

tests/HeadlessTest.Ursa/Controls/AspectRatioLayoutItemTests/AspectRatioLayoutItemTests.cs

@@ -0,0 +1,203 @@
+using Avalonia.Controls;
+using Avalonia.Headless.XUnit;
+using UrsaControls = Ursa.Controls;
+
+namespace HeadlessTest.Ursa.Controls.AspectRatioLayoutItemTests;
+
+public class AspectRatioLayoutItemTests
+{
+    [AvaloniaFact]
+    public void AspectRatioLayoutItem_Should_Initialize_With_Default_Values()
+    {
+        // Arrange & Act
+        var item = new UrsaControls.AspectRatioLayoutItem();
+
+        // Assert
+        Assert.Equal(UrsaControls.AspectRatioMode.None, item.AcceptAspectRatioMode);
+        Assert.True(double.IsNaN(item.StartAspectRatioValue));
+        Assert.True(double.IsNaN(item.EndAspectRatioValue));
+        Assert.False(item.IsUseAspectRatioRange);
+    }
+
+    [AvaloniaFact]
+    public void AspectRatioLayoutItem_Should_Set_AcceptAspectRatioMode_Property()
+    {
+        // Arrange
+        var window = new Window();
+        var item = new UrsaControls.AspectRatioLayoutItem();
+        window.Content = item;
+        window.Show();
+
+        // Act
+        item.AcceptAspectRatioMode = UrsaControls.AspectRatioMode.Square;
+
+        // Assert
+        Assert.Equal(UrsaControls.AspectRatioMode.Square, item.AcceptAspectRatioMode);
+    }
+
+    [AvaloniaFact]
+    public void AspectRatioLayoutItem_Should_Set_StartAspectRatioValue_Property()
+    {
+        // Arrange
+        var window = new Window();
+        var item = new UrsaControls.AspectRatioLayoutItem();
+        window.Content = item;
+        window.Show();
+
+        // Act
+        item.StartAspectRatioValue = 1.5;
+
+        // Assert
+        Assert.Equal(1.5, item.StartAspectRatioValue);
+    }
+
+    [AvaloniaFact]
+    public void AspectRatioLayoutItem_Should_Set_EndAspectRatioValue_Property()
+    {
+        // Arrange
+        var window = new Window();
+        var item = new UrsaControls.AspectRatioLayoutItem();
+        window.Content = item;
+        window.Show();
+
+        // Act
+        item.EndAspectRatioValue = 2.5;
+
+        // Assert
+        Assert.Equal(2.5, item.EndAspectRatioValue);
+    }
+
+    [AvaloniaFact]
+    public void AspectRatioLayoutItem_Should_Calculate_IsUseAspectRatioRange_Correctly()
+    {
+        // Arrange
+        var item = new UrsaControls.AspectRatioLayoutItem();
+
+        // Act & Assert - Default values (NaN) should return false
+        Assert.False(item.IsUseAspectRatioRange);
+
+        // Act - Set only start value
+        item.StartAspectRatioValue = 1.0;
+        Assert.False(item.IsUseAspectRatioRange);
+
+        // Act - Set only end value
+        item.StartAspectRatioValue = double.NaN;
+        item.EndAspectRatioValue = 2.0;
+        Assert.False(item.IsUseAspectRatioRange);
+
+        // Act - Set both values with start > end (invalid range)
+        item.StartAspectRatioValue = 3.0;
+        item.EndAspectRatioValue = 2.0;
+        Assert.False(item.IsUseAspectRatioRange);
+
+        // Act - Set valid range
+        item.StartAspectRatioValue = 1.0;
+        item.EndAspectRatioValue = 2.0;
+        Assert.True(item.IsUseAspectRatioRange);
+    }
+
+    [AvaloniaFact]
+    public void AspectRatioLayoutItem_Should_Support_Equal_Start_And_End_Values()
+    {
+        // Arrange
+        var item = new UrsaControls.AspectRatioLayoutItem();
+
+        // Act - Set equal start and end values
+        item.StartAspectRatioValue = 1.5;
+        item.EndAspectRatioValue = 1.5;
+
+        // Assert
+        Assert.True(item.IsUseAspectRatioRange);
+    }
+
+    [AvaloniaFact]
+    public void AspectRatioLayoutItem_Should_Set_Content_Property()
+    {
+        // Arrange
+        var window = new Window();
+        var item = new UrsaControls.AspectRatioLayoutItem();
+        var content = new Button { Content = "Test Content" };
+        window.Content = item;
+        window.Show();
+
+        // Act
+        item.Content = content;
+
+        // Assert
+        Assert.Equal(content, item.Content);
+    }
+
+    [AvaloniaFact]
+    public void AspectRatioLayoutItem_Should_Be_Visible_When_Added_To_Window()
+    {
+        // Arrange
+        var window = new Window();
+        var item = new UrsaControls.AspectRatioLayoutItem();
+
+        // Act
+        window.Content = item;
+        window.Show();
+
+        // Assert
+        Assert.True(item.IsVisible);
+    }
+
+    [AvaloniaFact]
+    public void AspectRatioLayoutItem_Should_Inherit_From_ContentControl()
+    {
+        // Arrange & Act
+        var item = new UrsaControls.AspectRatioLayoutItem();
+
+        // Assert
+        Assert.IsAssignableFrom<ContentControl>(item);
+    }
+
+    [AvaloniaFact]
+    public void AspectRatioLayoutItem_Should_Handle_Zero_Values()
+    {
+        // Arrange
+        var item = new UrsaControls.AspectRatioLayoutItem();
+
+        // Act
+        item.StartAspectRatioValue = 0.0;
+        item.EndAspectRatioValue = 1.0;
+
+        // Assert
+        Assert.True(item.IsUseAspectRatioRange);
+        Assert.Equal(0.0, item.StartAspectRatioValue);
+        Assert.Equal(1.0, item.EndAspectRatioValue);
+    }
+
+    [AvaloniaFact]
+    public void AspectRatioLayoutItem_Should_Handle_Negative_Values()
+    {
+        // Arrange
+        var item = new UrsaControls.AspectRatioLayoutItem();
+
+        // Act
+        item.StartAspectRatioValue = -1.0;
+        item.EndAspectRatioValue = 1.0;
+
+        // Assert
+        Assert.True(item.IsUseAspectRatioRange);
+        Assert.Equal(-1.0, item.StartAspectRatioValue);
+        Assert.Equal(1.0, item.EndAspectRatioValue);
+    }
+
+    [AvaloniaFact]
+    public void AspectRatioLayoutItem_Should_Reset_To_NaN()
+    {
+        // Arrange
+        var item = new UrsaControls.AspectRatioLayoutItem();
+        item.StartAspectRatioValue = 1.0;
+        item.EndAspectRatioValue = 2.0;
+
+        // Act
+        item.StartAspectRatioValue = double.NaN;
+
+        // Assert
+        Assert.False(item.IsUseAspectRatioRange);
+        Assert.True(double.IsNaN(item.StartAspectRatioValue));
+        Assert.Equal(2.0, item.EndAspectRatioValue);
+    }
+}