Fixed [ObservableProperty] within regions

Author: Sergio0694

Microsoft.Toolkit.Mvvm.SourceGenerators/ComponentModel/ObservablePropertyGenerator.cs

@@ -434,7 +434,7 @@ private static PropertyDeclarationSyntax CreatePropertyDeclaration(
                     AttributeList(SingletonSeparatedList(Attribute(IdentifierName("global::System.Diagnostics.DebuggerNonUserCode")))),
                     AttributeList(SingletonSeparatedList(Attribute(IdentifierName("global::System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage")))))
                 .AddAttributeLists(validationAttributes.Select(static a => AttributeList(SingletonSeparatedList(a))).ToArray())
-                .WithLeadingTrivia(leadingTrivia)
+                .WithLeadingTrivia(leadingTrivia.Where(static trivia => !trivia.IsKind(SyntaxKind.RegionDirectiveTrivia) && !trivia.IsKind(SyntaxKind.EndRegionDirectiveTrivia)))
                 .AddModifiers(Token(SyntaxKind.PublicKeyword))
                 .AddAccessorListAccessors(
                     AccessorDeclaration(SyntaxKind.GetAccessorDeclaration)

UnitTests/UnitTests.NetCore/Mvvm/Test_ObservablePropertyAttribute.cs

@@ -11,6 +11,8 @@
 using Microsoft.Toolkit.Mvvm.ComponentModel;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 
+#pragma warning disable SA1124
+
 #nullable enable
 
 namespace UnitTests.Mvvm
@@ -58,6 +60,86 @@ public void Test_ObservablePropertyAttribute_Events()
             Assert.AreEqual(changed.Item2, 42);
         }
 
+        // See https://github.com/CommunityToolkit/WindowsCommunityToolkit/issues/4225
+        [TestCategory("Mvvm")]
+        [TestMethod]
+        public void Test_ObservablePropertyAttributeWithinRegion_Events()
+        {
+            var model = new SampleModel();
+
+            (PropertyChangingEventArgs, int) changing = default;
+            (PropertyChangedEventArgs, int) changed = default;
+
+            model.PropertyChanging += (s, e) =>
+            {
+                Assert.IsNull(changing.Item1);
+                Assert.IsNull(changed.Item1);
+                Assert.AreSame(model, s);
+                Assert.IsNotNull(s);
+                Assert.IsNotNull(e);
+
+                changing = (e, model.Counter);
+            };
+
+            model.PropertyChanged += (s, e) =>
+            {
+                Assert.IsNotNull(changing.Item1);
+                Assert.IsNull(changed.Item1);
+                Assert.AreSame(model, s);
+                Assert.IsNotNull(s);
+                Assert.IsNotNull(e);
+
+                changed = (e, model.Counter);
+            };
+
+            model.Counter = 42;
+
+            Assert.AreEqual(changing.Item1?.PropertyName, nameof(SampleModel.Counter));
+            Assert.AreEqual(changing.Item2, 0);
+            Assert.AreEqual(changed.Item1?.PropertyName, nameof(SampleModel.Counter));
+            Assert.AreEqual(changed.Item2, 42);
+        }
+
+        // See https://github.com/CommunityToolkit/WindowsCommunityToolkit/issues/4225
+        [TestCategory("Mvvm")]
+        [TestMethod]
+        public void Test_ObservablePropertyAttributeRightBelowRegion_Events()
+        {
+            var model = new SampleModel();
+
+            (PropertyChangingEventArgs, string?) changing = default;
+            (PropertyChangedEventArgs, string?) changed = default;
+
+            model.PropertyChanging += (s, e) =>
+            {
+                Assert.IsNull(changing.Item1);
+                Assert.IsNull(changed.Item1);
+                Assert.AreSame(model, s);
+                Assert.IsNotNull(s);
+                Assert.IsNotNull(e);
+
+                changing = (e, model.Name);
+            };
+
+            model.PropertyChanged += (s, e) =>
+            {
+                Assert.IsNotNull(changing.Item1);
+                Assert.IsNull(changed.Item1);
+                Assert.AreSame(model, s);
+                Assert.IsNotNull(s);
+                Assert.IsNotNull(e);
+
+                changed = (e, model.Name);
+            };
+
+            model.Name = "Bob";
+
+            Assert.AreEqual(changing.Item1?.PropertyName, nameof(SampleModel.Name));
+            Assert.AreEqual(changing.Item2, null);
+            Assert.AreEqual(changed.Item1?.PropertyName, nameof(SampleModel.Name));
+            Assert.AreEqual(changed.Item2, "Bob");
+        }
+
         [TestCategory("Mvvm")]
         [TestMethod]
         public void Test_AlsoNotifyChangeForAttribute_Events()
@@ -162,6 +244,16 @@ public partial class SampleModel : ObservableObject
             /// </summary>
             [ObservableProperty]
             private int data;
+
+            #region More properties
+
+            [ObservableProperty]
+            private int counter;
+
+            #endregion
+
+            [ObservableProperty]
+            private string? name;
         }
 
         [INotifyPropertyChanged]