Add ReactiveCollection source generator and tests (#271)

* merge

* Add ReactiveCollection source generator and tests

Introduces the [ReactiveCollection] Attribute and its source generator, enabling automatic property generation for ObservableCollection OnChanged fields. Adds corresponding unit tests and verified outputs, updates test helpers, and includes usage in InternalTestViewModel.

* Revert tests

Author: ChrisPulman

src/ReactiveUI.SourceGenerator.Tests/DERIVEDLIST/BindableDerivedListGeneratorTests.FromReactiveProperties#ReactiveUI.SourceGenerators.BindableDerivedListAttribute.g.verified.cs

@@ -13,7 +13,6 @@ namespace ReactiveUI.SourceGenerators;
 /// ReactiveAttribute.
 /// </summary>
 /// <seealso cref="Attribute" />
-[global::System.CodeDom.Compiler.GeneratedCode("ReactiveUI.SourceGenerators.ReactiveGenerator", "2.3.0.0")]
 [global::System.AttributeUsage(global::System.AttributeTargets.Field, AllowMultiple = false, Inherited = false)]
 internal sealed class BindableDerivedListAttribute : global::System.Attribute;
 #nullable restore

src/ReactiveUI.SourceGenerator.Tests/DERIVEDLIST/ReactiveCollectionGeneratorTests.FromReactiveCollectionField#ReactiveUI.SourceGenerators.BindableDerivedListAttribute.g.verified.cs

@@ -0,0 +1,21 @@
+//HintName: ReactiveUI.SourceGenerators.BindableDerivedListAttribute.g.cs
+// Copyright (c) 2025 .NET Foundation and Contributors. All rights reserved.
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for full license information.
+
+using System;
+
+// <auto-generated/>
+#pragma warning disable
+#nullable enable
+namespace ReactiveUI.SourceGenerators;
+
+/// <summary>
+/// ReactiveAttribute.
+/// </summary>
+/// <seealso cref="Attribute" />
+[AttributeUsage(AttributeTargets.Field, AllowMultiple = false, Inherited = false)]
+internal sealed class BindableDerivedListAttribute : Attribute;
+#nullable restore
+#pragma warning restore

src/ReactiveUI.SourceGenerator.Tests/IVIEWFOR/IViewForGeneratorTests.FromIViewFor#ReactiveUI.SourceGenerators.IViewForAttribute.g.verified.cs

@@ -0,0 +1,34 @@
+//HintName: ReactiveUI.SourceGenerators.IViewForAttribute.g.cs
+// Copyright (c) 2025 .NET Foundation and Contributors. All rights reserved.
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for full license information.
+
+// <auto-generated/>
+#pragma warning disable
+#nullable enable
+namespace ReactiveUI.SourceGenerators;
+
+/// <summary>
+/// IViewForAttribute.
+/// </summary>
+/// <seealso cref="System.Attribute" />
+/// <remarks>
+/// Initializes a new instance of the <see cref="IViewForAttribute"/> class.
+/// </remarks>
+/// <param name="viewModelType">Type of the view model.</param>
+[global::System.AttributeUsage(global::System.AttributeTargets.Class, AllowMultiple = false, Inherited = false)]
+internal sealed class IViewForAttribute<T> : global::System.Attribute;
+
+/// <summary>
+/// IViewForAttribute.
+/// </summary>
+/// <seealso cref="System.Attribute" />
+/// <remarks>
+/// Initializes a new instance of the <see cref="IViewForAttribute"/> class.
+/// </remarks>
+/// <param name="viewModelType">Type of the view model.</param>
+[global::System.AttributeUsage(global::System.AttributeTargets.Class, AllowMultiple = false, Inherited = false)]
+internal sealed class IViewForAttribute(string? viewModelType) : global::System.Attribute;
+#nullable restore
+#pragma warning restore

src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromField#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs

@@ -13,7 +13,6 @@ namespace ReactiveUI.SourceGenerators;
 /// ObservableAsPropertyAttribute.
 /// </summary>
 /// <seealso cref="Attribute" />
-[global::System.CodeDom.Compiler.GeneratedCode("ReactiveUI.SourceGenerators.ObservableAsPropertyGenerator", "1.1.0.0")]
 [global::System.AttributeUsage(global::System.AttributeTargets.Field | global::System.AttributeTargets.Property | global::System.AttributeTargets.Method, AllowMultiple = false, Inherited = false)]
 internal sealed class ObservableAsPropertyAttribute : global::System.Attribute
 {

src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromField#TestNs.TestVM.ObservableAsProperties.g.verified.cs

@@ -11,7 +11,6 @@ public partial class TestVM
         private readonly ReactiveUI.ObservableAsPropertyHelper<double?> _testPropertyHelper;
 
         /// <inheritdoc cref="_testProperty"/>
-        [global::System.CodeDom.Compiler.GeneratedCode("ReactiveUI.SourceGenerators.ObservableAsPropertyGenerator", "2.3.0.0")]
         [global::System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
         [global::System.Runtime.Serialization.DataMemberAttribute()]
         [global::System.Text.Json.Serialization.JsonIncludeAttribute()]

src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromObservableMethods#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs

@@ -13,7 +13,6 @@ namespace ReactiveUI.SourceGenerators;
 /// ObservableAsPropertyAttribute.
 /// </summary>
 /// <seealso cref="Attribute" />
-[global::System.CodeDom.Compiler.GeneratedCode("ReactiveUI.SourceGenerators.ObservableAsPropertyGenerator", "1.1.0.0")]
 [global::System.AttributeUsage(global::System.AttributeTargets.Field | global::System.AttributeTargets.Property | global::System.AttributeTargets.Method, AllowMultiple = false, Inherited = false)]
 internal sealed class ObservableAsPropertyAttribute : global::System.Attribute
 {

src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromObservableMethods#TestNs.TestVM.ObservableAsPropertyFromObservable.g.verified.cs

@@ -17,11 +17,9 @@ public partial class TestVM
         private ReactiveUI.ObservableAsPropertyHelper<int>? _test2PropertyHelper;
 
         /// <inheritdoc cref="_test2Property"/>
-        [global::System.CodeDom.Compiler.GeneratedCode("ReactiveUI.SourceGenerators.ObservableAsPropertyGenerator", "2.3.0.0")]
         [global::System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
         public int Test2Property { get => _test2Property = _test2PropertyHelper?.Value ?? _test2Property; }
 
-        [global::System.CodeDom.Compiler.GeneratedCode("ReactiveUI.SourceGenerators.ObservableAsPropertyGenerator", "2.3.0.0")]
         [global::System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
         protected void InitializeOAPH()
         {

src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromObservableMethodsWithName#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs

@@ -13,7 +13,6 @@ namespace ReactiveUI.SourceGenerators;
 /// ObservableAsPropertyAttribute.
 /// </summary>
 /// <seealso cref="Attribute" />
-[global::System.CodeDom.Compiler.GeneratedCode("ReactiveUI.SourceGenerators.ObservableAsPropertyGenerator", "1.1.0.0")]
 [global::System.AttributeUsage(global::System.AttributeTargets.Field | global::System.AttributeTargets.Property | global::System.AttributeTargets.Method, AllowMultiple = false, Inherited = false)]
 internal sealed class ObservableAsPropertyAttribute : global::System.Attribute
 {

src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromObservableMethodsWithName#TestNs.TestVM.ObservableAsPropertyFromObservable.g.verified.cs

@@ -17,11 +17,9 @@ public partial class TestVM
         private ReactiveUI.ObservableAsPropertyHelper<int>? _test3PropertyHelper;
 
         /// <inheritdoc cref="_test3Property"/>
-        [global::System.CodeDom.Compiler.GeneratedCode("ReactiveUI.SourceGenerators.ObservableAsPropertyGenerator", "2.3.0.0")]
         [global::System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
         public int Test3Property { get => _test3Property = _test3PropertyHelper?.Value ?? _test3Property; }
 
-        [global::System.CodeDom.Compiler.GeneratedCode("ReactiveUI.SourceGenerators.ObservableAsPropertyGenerator", "2.3.0.0")]
         [global::System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
         protected void InitializeOAPH()
         {

src/ReactiveUI.SourceGenerator.Tests/OAPH/OAPFromObservableGeneratorTests.FromObservableProp#ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute.g.verified.cs

@@ -13,7 +13,6 @@ namespace ReactiveUI.SourceGenerators;
 /// ObservableAsPropertyAttribute.
 /// </summary>
 /// <seealso cref="Attribute" />
-[global::System.CodeDom.Compiler.GeneratedCode("ReactiveUI.SourceGenerators.ObservableAsPropertyGenerator", "1.1.0.0")]
 [global::System.AttributeUsage(global::System.AttributeTargets.Field | global::System.AttributeTargets.Property | global::System.AttributeTargets.Method, AllowMultiple = false, Inherited = false)]
 internal sealed class ObservableAsPropertyAttribute : global::System.Attribute
 {