Add 'partial' for nested types too, add tests

components/DependencyPropertyGenerator/CommunityToolkit.DependencyPropertyGenerator.CodeFixers/UseGeneratedDependencyPropertyOnManualPropertyCodeFixer.cs

@@ -319,14 +319,17 @@ private static void ConvertToPartialProperty(
         // Also remove the field declaration (it'll be generated now)
         syntaxEditor.RemoveNode(fieldDeclaration);
 
-        // Find the parent type for the property
-        TypeDeclarationSyntax typeDeclaration = propertyDeclaration.FirstAncestorOrSelf<TypeDeclarationSyntax>()!;
-
-        // Make sure it's partial (we create the updated node in the function to preserve the updated property declaration).
-        // If we created it separately and replaced it, the whole tree would also be replaced, and we'd lose the new property.
-        if (!typeDeclaration.Modifiers.Any(SyntaxKind.PartialKeyword))
+        // Find the parent type for the property (we need to do this for all ancestor types, as the type might be bested)
+        for (TypeDeclarationSyntax? typeDeclaration = propertyDeclaration.FirstAncestor<TypeDeclarationSyntax>();
+             typeDeclaration is not null;
+             typeDeclaration = typeDeclaration.FirstAncestor<TypeDeclarationSyntax>())
         {
-            syntaxEditor.ReplaceNode(typeDeclaration, static (node, generator) => generator.WithModifiers(node, generator.GetModifiers(node).WithPartial(true)));
+            // Make sure it's partial (we create the updated node in the function to preserve the updated property declaration).
+            // If we created it separately and replaced it, the whole tree would also be replaced, and we'd lose the new property.
+            if (!typeDeclaration.Modifiers.Any(SyntaxKind.PartialKeyword))
+            {
+                syntaxEditor.ReplaceNode(typeDeclaration, static (node, generator) => generator.WithModifiers(node, generator.GetModifiers(node).WithPartial(true)));
+            }
         }
     }
 

components/DependencyPropertyGenerator/CommunityToolkit.DependencyPropertyGenerator.Tests/Test_UseGeneratedDependencyPropertyOnManualPropertyCodeFixer.cs

@@ -1254,4 +1254,60 @@ public double? VerticalOffset
 
         await test.RunAsync();
     }
+
+    [TestMethod]
+    public async Task SimpleProperty_NestedType_AddsAllRequiredPartialModifiers()
+    {
+        const string original = """
+            using Windows.UI.Xaml;
+
+            #nullable enable
+
+            namespace MyApp;
+
+            public class MyObject : DependencyObject
+            {
+                public class MyNestedObject : DependencyObject
+                {
+                    public static readonly DependencyProperty NameProperty = DependencyProperty.Register(
+                        name: "Name",
+                        propertyType: typeof(string),
+                        ownerType: typeof(MyNestedObject),
+                        typeMetadata: null);
+
+                    public string? [|Name|]
+                    {
+                        get => (string?)GetValue(NameProperty);
+                        set => SetValue(NameProperty, value);
+                    }
+                }
+            }
+            """;
+
+        const string @fixed = """
+            using CommunityToolkit.WinUI;
+            using Windows.UI.Xaml;
+
+            #nullable enable
+
+            namespace MyApp;
+
+            public partial class MyObject : DependencyObject
+            {
+                public partial class MyNestedObject : DependencyObject
+                {
+                    [GeneratedDependencyProperty]
+                    public partial string? {|CS9248:Name|} { get; set; }
+                }
+            }
+            """;
+
+        CSharpCodeFixTest test = new(LanguageVersion.Preview)
+        {
+            TestCode = original,
+            FixedCode = @fixed
+        };
+
+        await test.RunAsync();
+    }
 }