Add ChangePropertyAction unit test

tests/Avalonia.Xaml.Interactions.UnitTests/Core/ChangePropertyActionTests.cs

@@ -0,0 +1,61 @@
+using Avalonia.Controls;
+using Avalonia.Headless;
+using Avalonia.Headless.XUnit;
+using Avalonia.Input;
+using Avalonia.Xaml.Interactions.Core;
+using Avalonia.Xaml.Interactivity;
+using Xunit;
+
+namespace Avalonia.Xaml.Interactions.UnitTests.Core;
+
+public class ChangePropertyActionTests
+{
+    [AvaloniaFact]
+    public void Should_Update_Text_Property_On_Click_Event()
+    {
+        var textBox = new TextBox
+        {
+            Text = "Initial Text"
+        };
+
+        var button = new Button
+        {
+            [Interaction.BehaviorsProperty] = new BehaviorCollection 
+            {
+                new EventTriggerBehavior
+                {
+                    EventName = "Click",
+                    Actions =
+                    {
+                        new ChangePropertyAction 
+                        { 
+                            TargetObject = textBox,
+                            PropertyName = "Text",
+                            Value = "Updated Text"
+                        }
+                    }
+                }
+            }
+        };
+
+        var window = new Window
+        {
+            Content = new StackPanel
+            {
+                Children =
+                {
+                    textBox,
+                    button
+                }
+            }
+        };
+
+        window.Show();
+
+        // Click
+        button.Focus();
+        window.KeyPress(Key.Enter, RawInputModifiers.None);
+
+        Assert.Equal("Updated Text", textBox.Text);
+    }
+}