Run check for disabled maximize button on Windows.

And also check with client-side decorations.

src/Avalonia.Themes.Fluent/Controls/CaptionButtons.xaml

@@ -48,7 +48,8 @@
             </Viewbox>
           </Button>
           <Button x:Name="PART_MinimiseButton"
-                  Theme="{StaticResource FluentCaptionButton}">
+                  Theme="{StaticResource FluentCaptionButton}"
+                  AutomationProperties.Name="Minimise">
             <Viewbox Width="11" Margin="2">
               <Path Stretch="UniformToFill"
                     Fill="{TemplateBinding Foreground}"
@@ -56,7 +57,8 @@
             </Viewbox>
           </Button>
           <Button x:Name="PART_RestoreButton"
-                  Theme="{StaticResource FluentCaptionButton}">
+                  Theme="{StaticResource FluentCaptionButton}"
+                  AutomationProperties.Name="Maximise">
             <Viewbox Width="11" Margin="2">
               <Viewbox.RenderTransform>
                 <RotateTransform Angle="-90" />
@@ -70,7 +72,8 @@
           <Button x:Name="PART_CloseButton"
                   Background="#ffe81123"
                   BorderBrush="#fff1707a"
-                  Theme="{StaticResource FluentCaptionButton}">
+                  Theme="{StaticResource FluentCaptionButton}"
+                  AutomationProperties.Name="Close">
             <Viewbox Width="11" Margin="2">
               <Path Stretch="UniformToFill"
                     Fill="{TemplateBinding Foreground}"

tests/Avalonia.IntegrationTests.Appium/WindowTests.cs

@@ -12,6 +12,7 @@ using OpenQA.Selenium.Interactions;
 using SixLabors.ImageSharp.PixelFormats;
 using Xunit;
 using Xunit.Sdk;
+using OpenQA.Selenium.Appium.Interfaces;
 
 namespace Avalonia.IntegrationTests.Appium
 {
@@ -249,6 +250,36 @@ namespace Avalonia.IntegrationTests.Appium
             Assert.Equal(new Rgba32(255, 0, 0), centerColor);
         }
 
+        [Theory]
+        [InlineData(ShowWindowMode.NonOwned, true)]
+        [InlineData(ShowWindowMode.Owned, true)]
+        [InlineData(ShowWindowMode.Modal, true)]
+        [InlineData(ShowWindowMode.NonOwned, false)]
+        [InlineData(ShowWindowMode.Owned, false)]
+        [InlineData(ShowWindowMode.Modal, false)]
+        public void Window_Has_Disabled_Maximize_Button_When_CanResize_Is_False(ShowWindowMode mode, bool extendClientArea)
+        {
+            using (OpenWindow(null, mode, WindowStartupLocation.Manual, canResize: false, extendClientArea: extendClientArea))
+            {
+                var secondaryWindow = GetWindow("SecondaryWindow");
+                AppiumWebElement? maximizeButton;
+
+                if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+                {
+                    var foo = _session.PageSource;
+                    maximizeButton = secondaryWindow.FindElementByXPath("//Button[@Name='Maximise']");
+                }
+                else
+                {
+                    maximizeButton = mode == ShowWindowMode.NonOwned ?
+                        secondaryWindow.FindElementByAccessibilityId("_XCUI:FullScreenWindow") :
+                        secondaryWindow.FindElementByAccessibilityId("_XCUI:ZoomWindow");
+                }
+
+                Assert.False(maximizeButton.Enabled);
+            }
+        }
+
         public static TheoryData<Size?, ShowWindowMode, WindowStartupLocation, bool> StartupLocationData()
         {
             var sizes = new Size?[] { null, new Size(400, 300) };
@@ -333,7 +364,8 @@ namespace Avalonia.IntegrationTests.Appium
             ShowWindowMode mode,
             WindowStartupLocation location = WindowStartupLocation.Manual,
             WindowState state = Controls.WindowState.Normal,
-            bool canResize = true)
+            bool canResize = true,
+            bool extendClientArea = false)
         {
             var sizeTextBox = _session.FindElementByAccessibilityId("ShowWindowSize");
             var modeComboBox = _session.FindElementByAccessibilityId("ShowWindowMode");
@@ -341,7 +373,8 @@ namespace Avalonia.IntegrationTests.Appium
             var stateComboBox = _session.FindElementByAccessibilityId("ShowWindowState");
             var canResizeCheckBox = _session.FindElementByAccessibilityId("ShowWindowCanResize");
             var showButton = _session.FindElementByAccessibilityId("ShowWindow");
-            
+            var extendClientAreaCheckBox = _session.FindElementByAccessibilityId("ShowWindowExtendClientAreaToDecorationsHint");
+
             if (size.HasValue)
                 sizeTextBox.SendKeys($"{size.Value.Width}, {size.Value.Height}");
 
@@ -366,9 +399,27 @@ namespace Avalonia.IntegrationTests.Appium
             if (canResizeCheckBox.GetIsChecked() != canResize)
                 canResizeCheckBox.Click();
 
+            if (extendClientAreaCheckBox.GetIsChecked() != extendClientArea)
+                extendClientAreaCheckBox.Click();
+
             return showButton.OpenWindowWithClick();
         }
 
+        private AppiumWebElement GetWindow(string identifier)
+        {
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+            {
+                // The Avalonia a11y tree currently exposes two nested Window elements, this is a bug and should be fixed 
+                // but in the meantime use the `parent::' selector to return the parent "real" window. 
+                return _session.FindElementByXPath(
+                    $"XCUIElementTypeWindow//*[@identifier='{identifier}']/parent::XCUIElementTypeWindow");
+            }
+            else
+            {
+                return _session.FindElementByXPath($"//Window[@AutomationId='{identifier}']");
+            }
+        }
+
         private WindowInfo GetWindowInfo()
         {
             PixelRect? ReadOwnerRect()

tests/Avalonia.IntegrationTests.Appium/WindowTests_MacOS.cs

@@ -336,22 +336,6 @@ namespace Avalonia.IntegrationTests.Appium
             secondaryWindow.FindElementByAccessibilityId("_XCUI:CloseWindow").Click();
         }
 
-        [PlatformTheory(TestPlatforms.MacOS)]
-        [InlineData(ShowWindowMode.NonOwned)]
-        [InlineData(ShowWindowMode.Owned)]
-        [InlineData(ShowWindowMode.Modal)]
-        public void Window_Has_Disabled_Zoom_Button_When_CanResize_Is_False(ShowWindowMode mode)
-        {
-            using (OpenWindow(null, mode, WindowStartupLocation.Manual, canResize: false))
-            {
-                var secondaryWindow = GetWindow("SecondaryWindow");
-                var zoomButton = mode == ShowWindowMode.NonOwned ?
-                    secondaryWindow.FindElementByAccessibilityId("_XCUI:FullScreenWindow") :
-                    secondaryWindow.FindElementByAccessibilityId("_XCUI:ZoomWindow");
-                Assert.False(zoomButton.Enabled);
-            }
-        }
-
         [PlatformFact(TestPlatforms.MacOS)]
         public void Toggling_SystemDecorations_Should_Preserve_ExtendClientArea()
         {