Content update - Add attached property snippet tests (user story 1878471) (#1224)

* Add snippet test and update type

* Add snippet test and update type

* Update to .NET to 6.0

* Update accessor signatures

dotnet-desktop-guide/net/wpf/properties/attached-properties-overview.md

@@ -95,9 +95,9 @@ The following example shows how to register a dependency property using the <xre
 
 #### The Get accessor
 
-The `get` accessor method signature is `public static object Get<property name>(object target)`, where:
+The `get` accessor method signature is `public static object Get<property name>(DependencyObject target)`, where:
 
-- `target` is the object from which the attached property is read. The `target` type can be more specific than `object`. For example, the <xref:System.Windows.Controls.DockPanel.GetDock%2A?displayProperty=nameWithType> accessor method types the `target` as <xref:System.Windows.UIElement> because the attached property is intended to be set on `UIElement` instances.
+- `target` is the <xref:System.Windows.DependencyObject> from which the attached property is read. The `target` type can be more specific than `DependencyObject`. For example, the <xref:System.Windows.Controls.DockPanel.GetDock%2A?displayProperty=nameWithType> accessor method types the `target` as <xref:System.Windows.UIElement> because the attached property is intended to be set on `UIElement` instances. `UiElement` indirectly derives from `DependencyObject`.
 - The return type can be more specific than `object`. For example, the <xref:System.Windows.Controls.DockPanel.GetDock%2A> method types the returned value as <xref:System.Windows.Controls.Dock> because the return value should be a `Dock` enumeration.
 
 > [!NOTE]
@@ -105,9 +105,9 @@ The `get` accessor method signature is `public static object Get<property name>(
 
 #### The Set accessor
 
-The `set` accessor method signature is `public static void Set<property name>(object target, object value)`, where:
+The `set` accessor method signature is `public static void Set<property name>(DependencyObject target, object value)`, where:
 
-- `target` is the object on which the attached property is written. The `target` type can be more specific than `object`. For example, the <xref:System.Windows.Controls.DockPanel.SetDock%2A> method types the `target` as <xref:System.Windows.UIElement> because the attached property is intended to be set on <xref:System.Windows.UIElement> instances.
+- `target` is the <xref:System.Windows.DependencyObject> on which the attached property is written. The `target` type can be more specific than `DependencyObject`. For example, the <xref:System.Windows.Controls.DockPanel.SetDock%2A> method types the `target` as <xref:System.Windows.UIElement> because the attached property is intended to be set on <xref:System.Windows.UIElement> instances. `UiElement` indirectly derives from `DependencyObject`.
 - The `value` type can be more specific than `object`. For example, the <xref:System.Windows.Controls.DockPanel.SetDock%2A> method requires a <xref:System.Windows.Controls.Dock> value. The XAML loader needs to be able to generate the `value` type from the markup string that represents the attached property value. So, there must be type conversion, value serializer, or markup extension support for the type you use.
 
 ### Attached property attributes

dotnet-desktop-guide/net/wpf/properties/snippets/attached-properties-overview/csharp/MainWindow.xaml.cs

@@ -1,4 +1,5 @@
-using System.Windows;
+using System.Diagnostics;
+using System.Windows;
 using System.Windows.Controls;
 
 namespace CodeSampleCsharp
@@ -13,6 +14,12 @@ namespace CodeSampleCsharp
             InitializeComponent();
 
             SetAttachedPropertyInCode();
+
+            // Test get/set accessors.
+            Aquarium aquarium = new();
+            Aquarium.SetHasFish(aquarium, true);
+            bool hasFish = Aquarium.GetHasFish(aquarium);
+            Debug.WriteLine($"Has fish: {hasFish}");
         }
 
         public static void SetAttachedPropertyInCode()
@@ -32,7 +39,7 @@ namespace CodeSampleCsharp
     }
 
     //<RegisterAttachedProperty>
-    public class Aquarium : DependencyObject
+    public class Aquarium : UIElement
     {
         // Register an attached dependency property with the specified
         // property name, property type, owner type, and property metadata.

dotnet-desktop-guide/net/wpf/properties/snippets/attached-properties-overview/vb/MainWindow.xaml.vb

@@ -10,6 +10,12 @@
             InitializeComponent()
 
             SetAttachedPropertyInCode()
+
+            ' Test get/set accessors.
+            Dim aquarium As New Aquarium()
+            aquarium.SetHasFish(aquarium, True)
+            Dim hasFish As Boolean = aquarium.GetHasFish(aquarium)
+            Debug.WriteLine($"Has fish: {hasFish}")
         End Sub
 
         Public Shared Sub SetAttachedPropertyInCode()
@@ -30,7 +36,7 @@
 
     '<RegisterAttachedProperty>
     Public Class Aquarium
-        Inherits DependencyObject
+        Inherits UIElement
 
         ' Register an attached dependency property with the specified
         ' property name, property type, owner type, and property metadata.

dotnet-desktop-guide/net/wpf/properties/snippets/how-to-register-an-attached-property/csharp/MainWindow.xaml.cs

@@ -1,5 +1,5 @@
-using System.Windows;
+using System.Diagnostics;
-using System.Windows.Controls;
+using System.Windows;
 
 namespace CodeSampleCsharp
 {
@@ -8,11 +8,20 @@ namespace CodeSampleCsharp
     /// </summary>
     public partial class MainWindow : Window
     {
-        public MainWindow() => InitializeComponent();
+        public MainWindow()
+        {
+            InitializeComponent();
+
+            // Test get/set accessors.
+            Aquarium aquarium = new();
+            Aquarium.SetHasFish(aquarium, true);
+            bool hasFish = Aquarium.GetHasFish(aquarium);
+            Debug.WriteLine($"Has fish: {hasFish}");
+        }
     }
 
     //<RegisterAttachedProperty>
-    public class Aquarium : DependencyObject
+    public class Aquarium : UIElement
     {
         // Register an attached dependency property with the specified
         // property name, property type, owner type, and property metadata.

dotnet-desktop-guide/net/wpf/properties/snippets/how-to-register-an-attached-property/vb/MainWindow.xaml.vb

@@ -8,13 +8,19 @@
 
         Public Sub New()
             InitializeComponent()
+
+            ' Test get/set accessors.
+            Dim aquarium As New Aquarium()
+            Aquarium.SetHasFish(aquarium, True)
+            Dim hasFish As Boolean = Aquarium.GetHasFish(aquarium)
+            Debug.WriteLine($"Has fish: {hasFish}")
         End Sub
 
     End Class
 
     '<RegisterAttachedProperty>
     Public Class Aquarium
-        Inherits DependencyObject
+        Inherits UIElement
 
         ' Register an attached dependency property with the specified
         ' property name, property type, owner type, and property metadata.