Add unit test for required properties

Author: Sergio0694

tests/CommunityToolkit.Mvvm.SourceGenerators.Roslyn4110.UnitTests/Test_SourceGeneratorsCodegen.cs

@@ -92,6 +92,82 @@ partial int Number
         VerifyGenerateSources(source, new[] { new ObservablePropertyGenerator() }, LanguageVersion.Preview, ("MyApp.MyViewModel.g.cs", result));
     }
 
+    // See https://github.com/CommunityToolkit/dotnet/issues/969
+    [TestMethod]
+    public void ObservablePropertyWithValueType_OnPartialProperty_RequiredProperty_WorksCorrectly()
+    {
+        string source = """
+            using System;
+            using CommunityToolkit.Mvvm.ComponentModel;
+
+            namespace MyApp;
+            
+            partial class MyViewModel : ObservableObject
+            {
+                [ObservableProperty]
+                public required partial int Number { get; private set; }
+            }
+            """;
+
+        string result = """
+            // <auto-generated/>
+            #pragma warning disable
+            #nullable enable
+            namespace MyApp
+            {
+                /// <inheritdoc/>
+                partial class MyViewModel
+                {
+                    /// <inheritdoc/>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    [global::System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
+                    public required partial int Number
+                    {
+                        get => field;
+                        private set
+                        {
+                            if (!global::System.Collections.Generic.EqualityComparer<int>.Default.Equals(field, value))
+                            {
+                                OnNumberChanging(value);
+                                OnNumberChanging(default, value);
+                                OnPropertyChanging(global::CommunityToolkit.Mvvm.ComponentModel.__Internals.__KnownINotifyPropertyChangingArgs.Number);
+                                field = value;
+                                OnNumberChanged(value);
+                                OnNumberChanged(default, value);
+                                OnPropertyChanged(global::CommunityToolkit.Mvvm.ComponentModel.__Internals.__KnownINotifyPropertyChangedArgs.Number);
+                            }
+                        }
+                    }
+
+                    /// <summary>Executes the logic for when <see cref="Number"/> is changing.</summary>
+                    /// <param name="value">The new property value being set.</param>
+                    /// <remarks>This method is invoked right before the value of <see cref="Number"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    partial void OnNumberChanging(int value);
+                    /// <summary>Executes the logic for when <see cref="Number"/> is changing.</summary>
+                    /// <param name="oldValue">The previous property value that is being replaced.</param>
+                    /// <param name="newValue">The new property value being set.</param>
+                    /// <remarks>This method is invoked right before the value of <see cref="Number"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    partial void OnNumberChanging(int oldValue, int newValue);
+                    /// <summary>Executes the logic for when <see cref="Number"/> just changed.</summary>
+                    /// <param name="value">The new property value that was set.</param>
+                    /// <remarks>This method is invoked right after the value of <see cref="Number"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    partial void OnNumberChanged(int value);
+                    /// <summary>Executes the logic for when <see cref="Number"/> just changed.</summary>
+                    /// <param name="oldValue">The previous property value that was replaced.</param>
+                    /// <param name="newValue">The new property value that was set.</param>
+                    /// <remarks>This method is invoked right after the value of <see cref="Number"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    partial void OnNumberChanged(int oldValue, int newValue);
+                }
+            }
+            """;
+
+        VerifyGenerateSources(source, new[] { new ObservablePropertyGenerator() }, LanguageVersion.Preview, ("MyApp.MyViewModel.g.cs", result));
+    }
+
     [TestMethod]
     public void ObservablePropertyWithValueType_OnPartialProperty_WithExplicitModifiers_WorksCorrectly1()
     {