Improve handling of attribute lists, fix tests

Author: Sergio0694

src/CommunityToolkit.Mvvm.CodeFixers/UsePartialPropertyForSemiAutoPropertyCodeFixer.cs

@@ -69,11 +69,40 @@ private static async Task<Document> ConvertToPartialProperty(Document document,
     {
         await Task.CompletedTask;
 
+        // Prepare the [ObservableProperty] attribute, which is always inserted first
+        AttributeListSyntax observablePropertyAttributeList = AttributeList(SingletonSeparatedList(Attribute(IdentifierName("ObservableProperty"))));
+
+        // Start setting up the updated attribute lists
+        SyntaxList<AttributeListSyntax> attributeLists = propertyDeclaration.AttributeLists;
+
+        if (attributeLists is [AttributeListSyntax firstAttributeListSyntax, ..])
+        {
+            // Remove the trivia from the original first attribute
+            attributeLists = attributeLists.Replace(
+                nodeInList: firstAttributeListSyntax,
+                newNode: firstAttributeListSyntax.WithoutTrivia());
+
+            // If the property has at least an attribute list, move the trivia from it to the new attribute
+            observablePropertyAttributeList = observablePropertyAttributeList.WithTriviaFrom(firstAttributeListSyntax);
+
+            // Insert the new attribute
+            attributeLists = attributeLists.Insert(0, observablePropertyAttributeList);
+        }
+        else
+        {
+            // Otherwise (there are no attribute lists), transfer the trivia to the new (only) attribute list
+            observablePropertyAttributeList = observablePropertyAttributeList.WithTriviaFrom(propertyDeclaration);
+
+            // Save the new attribute list
+            attributeLists = attributeLists.Add(observablePropertyAttributeList);
+        }
+
         // Get a new property that is partial and with semicolon token accessors
         PropertyDeclarationSyntax updatedPropertyDeclaration =
             propertyDeclaration
             .AddModifiers(Token(SyntaxKind.PartialKeyword))
-            .AddAttributeLists(AttributeList(SingletonSeparatedList(Attribute(IdentifierName("ObservableProperty")))))
+            .WithoutTrivia()
+            .WithAttributeLists(attributeLists)
             .WithAdditionalAnnotations(Formatter.Annotation)
             .WithAccessorList(AccessorList(List(
             [

tests/CommunityToolkit.Mvvm.SourceGenerators.Roslyn4120.UnitTests/Test_UseObservablePropertyOnSemiAutoPropertyCodeFixer.cs

@@ -126,8 +126,8 @@ public partial class SampleViewModel : ObservableObject
 
         test.FixedState.ExpectedDiagnostics.AddRange(new[]
         {
-            // /0/Test0.cs(8,27): error CS9248: Partial property 'SampleViewModel.Name' must have an implementation part.
-            DiagnosticResult.CompilerError("CS9248").WithSpan(8, 27, 8, 31).WithArguments("MyApp.SampleViewModel.Name"),
+            // /0/Test0.cs(11,27): error CS9248: Partial property 'SampleViewModel.Name' must have an implementation part.
+            DiagnosticResult.CompilerError("CS9248").WithSpan(11, 27, 11, 31).WithArguments("MyApp.SampleViewModel.Name"),
         });
 
         await test.RunAsync();
@@ -175,6 +175,8 @@ public partial class SampleViewModel : ObservableObject
                 [field: Test("Targeting field")]
                 public partial string Name { get; set; }
             }
+
+            public class TestAttribute(string text) : Attribute;
             """;
 
         CSharpCodeFixTest test = new(LanguageVersion.Preview)
@@ -193,8 +195,8 @@ public partial class SampleViewModel : ObservableObject
 
         test.FixedState.ExpectedDiagnostics.AddRange(new[]
         {
-            // /0/Test0.cs(8,27): error CS9248: Partial property 'SampleViewModel.Name' must have an implementation part.
-            DiagnosticResult.CompilerError("CS9248").WithSpan(8, 27, 8, 31).WithArguments("MyApp.SampleViewModel.Name"),
+            // /0/Test0.cs(14,27): error CS9248: Partial property 'SampleViewModel.Name' must have an implementation part.
+            DiagnosticResult.CompilerError("CS9248").WithSpan(14, 27, 14, 31).WithArguments("MyApp.SampleViewModel.Name"),
         });
 
         await test.RunAsync();
@@ -447,29 +449,29 @@ namespace MyApp;
 
             public partial class SampleViewModel : ObservableObject
             {
-                [ObservableAttribute]
+                [ObservableProperty]
                 [Test("This is an attribute")]
                 public partial string Prop1 { get; set; }
 
                 // Single comment
-                [ObservableAttribute]
+                [ObservableProperty]
                 public partial string Prop2 { get; set; }
 
                 /// <summary>
                 /// This is a property.
                 /// </summary>
-                [ObservableAttribute]
+                [ObservableProperty]
                 public partial string Prop3 { get; set; }
 
                 /// <summary>
                 /// This is another property.
                 /// </summary>
-                [ObservableAttribute]
+                [ObservableProperty]
                 [Test("Another attribute")]
                 public partial string Prop4 { get; set; }
 
                 // Some other single comment
-                [ObservableAttribute]
+                [ObservableProperty]
                 [Test("Yet another attribute")]
                 public partial string Prop5 { get; set; }
             }
@@ -505,8 +507,20 @@ public class TestAttribute(string text) : Attribute;
 
         test.FixedState.ExpectedDiagnostics.AddRange(new[]
         {
-            // /0/Test0.cs(8,27): error CS9248: Partial property 'SampleViewModel.Name' must have an implementation part.
-            DiagnosticResult.CompilerError("CS9248").WithSpan(8, 27, 8, 31).WithArguments("MyApp.SampleViewModel.Name"),
+            // /0/Test0.cs(10,27): error CS9248: Partial property 'SampleViewModel.Prop1' must have an implementation part.
+            DiagnosticResult.CompilerError("CS9248").WithSpan(10, 27, 10, 32).WithArguments("MyApp.SampleViewModel.Prop1"),
+
+            // /0/Test0.cs(14,27): error CS9248: Partial property 'SampleViewModel.Prop2' must have an implementation part.
+            DiagnosticResult.CompilerError("CS9248").WithSpan(14, 27, 14, 32).WithArguments("MyApp.SampleViewModel.Prop2"),
+
+            // /0/Test0.cs(20,27): error CS9248: Partial property 'SampleViewModel.Prop3' must have an implementation part.
+            DiagnosticResult.CompilerError("CS9248").WithSpan(20, 27, 20, 32).WithArguments("MyApp.SampleViewModel.Prop3"),
+
+            // /0/Test0.cs(27,27): error CS9248: Partial property 'SampleViewModel.Prop4' must have an implementation part.
+            DiagnosticResult.CompilerError("CS9248").WithSpan(27, 27, 27, 32).WithArguments("MyApp.SampleViewModel.Prop4"),
+
+            // /0/Test0.cs(32,27): error CS9248: Partial property 'SampleViewModel.Prop5' must have an implementation part.
+            DiagnosticResult.CompilerError("CS9248").WithSpan(32, 27, 32, 32).WithArguments("MyApp.SampleViewModel.Prop5"),
         });
 
         await test.RunAsync();