Moved all extension methods into extension blocks (#1155)

app/Tests/Analyzers/ClassicExtensionMethodAnalyzerTests.cs

@@ -0,0 +1,69 @@
+using AIStudio.Tests.Models.Generation;
+
+using Microsoft.CodeAnalysis;
+
+using SourceCodeRules.StyleAnalyzers;
+
+namespace AIStudio.Tests.Analyzers;
+
+/// <summary>
+/// Checks that extension methods are declared in extension blocks, not with a this parameter.
+/// </summary>
+/// <remarks>
+/// AI Studio declares all its extension members in extension blocks, one per receiver. MWAIS0016 refuses the
+/// classic form while compiling, except for a method with a params parameter: for a member of an extension
+/// block, the compiler of the .NET 10.0.1xx SDK warns about every argument passed one by one to a params
+/// parameter (CS8620, dotnet/roslyn#80024).
+/// </remarks>
+[TestFixture]
+public sealed class ClassicExtensionMethodAnalyzerTests
+{
+    [TestCase("public static string Label(this Meeting meeting) => meeting.Name;", "Label", TestName = "A public extension method")]
+    [TestCase("private static string Label(this Meeting meeting) => meeting.Name;", "Label", TestName = "A private extension method")]
+    [TestCase("public static string Label(this Meeting meeting, string prefix) => prefix + meeting.Name;", "Label", TestName = "An extension method with further parameters")]
+    [TestCase("public static T Echo<T>(this T value) where T : class => value;", "Echo", TestName = "A generic extension method")]
+    [TestCase("public static void Bump(this ref int value) => value++;", "Bump", TestName = "An extension method with a ref receiver")]
+    [TestCase("public static System.Threading.Tasks.Task<string> LabelAsync(this Meeting meeting) => System.Threading.Tasks.Task.FromResult(meeting.Name);", "LabelAsync", TestName = "An asynchronous extension method")]
+    public async Task AClassicExtensionMethodIsRefused(string member, string name)
+    {
+        var reported = await AnalyzeAsync(member);
+
+        using (Assert.EnterMultipleScope())
+        {
+            Assert.That(reported, Has.Count.EqualTo(1));
+            Assert.That(reported.FirstOrDefault()?.Id, Is.EqualTo("MWAIS0016"));
+            Assert.That(reported.FirstOrDefault()?.GetMessage(), Does.Contain($"'{name}'"));
+        }
+    }
+
+    [TestCase("extension(Meeting meeting) { public string Label() => meeting.Name; }", TestName = "A member of an extension block")]
+    [TestCase("extension<T>(T value) where T : class { public T Echo() => value; }", TestName = "A member of a generic extension block")]
+    [TestCase("public static string Label(Meeting meeting) => meeting.Name;", TestName = "A static method without a this parameter")]
+    [TestCase("public static string Label(this Meeting meeting, params string[] prefixes) => string.Concat(prefixes) + meeting.Name;", TestName = "An extension method with a params parameter")]
+    public async Task AnythingElseIsLeftAlone(string member)
+    {
+        var reported = await AnalyzeAsync(member);
+
+        Assert.That(reported, Is.Empty);
+    }
+
+    private static async Task<IReadOnlyList<Diagnostic>> AnalyzeAsync(string member)
+    {
+        var source =
+            $$"""
+              namespace Sample;
+
+              public sealed class Meeting
+              {
+                  public string Name { get; set; } = "Kickoff";
+              }
+
+              public static class MeetingExtensions
+              {
+                  {{member}}
+              }
+              """;
+
+        return await CompilationHarness.AnalyzeAsync(source, new ClassicExtensionMethodAnalyzer());
+    }
+}

app/Tests/Analyzers/DirectI18NGetTextAnalyzerTests.cs

@@ -0,0 +1,121 @@
+using AIStudio.Tests.Models.Generation;
+
+using Microsoft.CodeAnalysis;
+
+using SourceCodeRules.UsageAnalyzers;
+
+namespace AIStudio.Tests.Analyzers;
+
+/// <summary>
+/// Checks that the texts of the app are looked up only through a T or TB wrapper, whose fallback text the I18N
+/// collector finds.
+/// </summary>
+/// <remarks>
+/// The collector reads the texts from calls of T and TB. A text handed to GetText anywhere else never reaches
+/// the language plugins, so it is never translated, and nothing at runtime shows it. MWAIS0012 refuses such a
+/// call while compiling. GetText is an extension method, so these tests ask in both of the forms C# knows for
+/// one: the classic method with a this parameter and the member of an extension block.
+/// </remarks>
+[TestFixture]
+public sealed class DirectI18NGetTextAnalyzerTests
+{
+    private const string CLASSIC_FORM =
+        """
+        public static class ILangExtensions
+        {
+            public static string GetText(this ILang lang, string fallbackEN) => fallbackEN;
+        }
+        """;
+
+    private const string EXTENSION_BLOCK_FORM =
+        """
+        public static class ILangExtensions
+        {
+            extension(ILang lang)
+            {
+                public string GetText(string fallbackEN) => fallbackEN;
+            }
+        }
+        """;
+
+    [TestCase(CLASSIC_FORM, "T", TestName = "A T wrapper around a classic extension method")]
+    [TestCase(CLASSIC_FORM, "TB", TestName = "A TB wrapper around a classic extension method")]
+    [TestCase(EXTENSION_BLOCK_FORM, "T", TestName = "A T wrapper around the member of an extension block")]
+    [TestCase(EXTENSION_BLOCK_FORM, "TB", TestName = "A TB wrapper around the member of an extension block")]
+    public async Task AWrapperWhichForwardsItsTextIsAllowed(string form, string wrapper)
+    {
+        var reported = await AnalyzeAsync(form, $"public string {wrapper}(string fallbackEN) => this.GetText(fallbackEN);");
+
+        Assert.That(reported, Is.Empty);
+    }
+
+    [TestCase(CLASSIC_FORM, """public string Describe() => this.GetText("Hello");""", TestName = "A classic extension method called from another method")]
+    [TestCase(CLASSIC_FORM, """public string T(string fallbackEN) => this.GetText("Hello");""", TestName = "A classic extension method called by a wrapper with a text of its own")]
+    [TestCase(CLASSIC_FORM, """public string Describe() => ILangExtensions.GetText(this, "Hello");""", TestName = "A classic extension method called as a static method")]
+    [TestCase(EXTENSION_BLOCK_FORM, """public string Describe() => this.GetText("Hello");""", TestName = "The member of an extension block called from another method")]
+    [TestCase(EXTENSION_BLOCK_FORM, """public string T(string fallbackEN) => this.GetText("Hello");""", TestName = "The member of an extension block called by a wrapper with a text of its own")]
+    [TestCase(EXTENSION_BLOCK_FORM, """public string Describe() => ILangExtensions.GetText(this, "Hello");""", TestName = "The member of an extension block called as a static method")]
+    public async Task ADirectLookupIsRefused(string form, string member)
+    {
+        var reported = await AnalyzeAsync(form, member);
+
+        using (Assert.EnterMultipleScope())
+        {
+            Assert.That(reported, Has.Count.EqualTo(1));
+            Assert.That(reported.FirstOrDefault()?.Id, Is.EqualTo("MWAIS0012"));
+        }
+    }
+
+    [TestCase("this.GetText(PLUGIN, fallbackEN)", 0, TestName = "The GetText of the app in a wrapper")]
+    [TestCase("""this.GetText(PLUGIN, "Hello")""", 1, TestName = "The GetText of the app in a wrapper with a text of its own")]
+    public async Task TheGetTextOfTheAppIsRecognized(string lookup, int expectedReports)
+    {
+        //
+        // Whatever form the app gives its GetText, the analyzer has to know it:
+        //
+        var source =
+            $$"""
+              using AIStudio.Tools.PluginSystem;
+
+              namespace Sample;
+
+              public sealed class Component : ILang
+              {
+                  private static readonly ILanguagePlugin PLUGIN = NoPluginLanguage.INSTANCE;
+
+                  public string T(string fallbackEN) => {{lookup}};
+
+                  public string T(string fallbackEN, string? typeNamespace, string? typeName) => fallbackEN;
+              }
+              """;
+
+        var reported = await CompilationHarness.AnalyzeAsync(source, new DirectI18NGetTextAnalyzer());
+
+        Assert.That(reported, Has.Count.EqualTo(expectedReports));
+    }
+
+    private static async Task<IReadOnlyList<Diagnostic>> AnalyzeAsync(string form, string member)
+    {
+        //
+        // The snippet declares its own ILang and ILangExtensions where the analyzer looks for them. They take
+        // the place of those of the app, which the compilation references as well.
+        //
+        var source =
+            $$"""
+              namespace AIStudio.Tools.PluginSystem;
+
+              public interface ILang
+              {
+              }
+
+              {{form}}
+
+              public sealed class Component : ILang
+              {
+                  {{member}}
+              }
+              """;
+
+        return await CompilationHarness.AnalyzeAsync(source, new DirectI18NGetTextAnalyzer());
+    }
+}

app/Tests/Analyzers/ThisUsageAnalyzerTests.cs

@@ -0,0 +1,143 @@
+using AIStudio.Tests.Models.Generation;
+
+using Microsoft.CodeAnalysis;
+
+using SourceCodeRules.UsageAnalyzers;
+
+namespace AIStudio.Tests.Analyzers;
+
+/// <summary>
+/// Checks which members MWAIS0005 wants to be reached through <c>this.</c>, and that extension methods are never
+/// asked for it.
+/// </summary>
+/// <remarks>
+/// An extension member has no <c>this</c>: a classic extension method is static, and in an extension block C#
+/// refuses the keyword. There, every instance member is reached through the name of the receiver, and a sibling
+/// member without it does not even compile. Should a later version of C# reach the receiver without its name,
+/// the analyzer would demand a <c>this.</c> which nobody can write, and the tests for extension blocks fail.
+/// </remarks>
+[TestFixture]
+public sealed class ThisUsageAnalyzerTests
+{
+    [TestCase("this.location", TestName = "A field through this")]
+    [TestCase("this.Name", TestName = "A property through this")]
+    [TestCase("this.Describe()", TestName = "A method through this")]
+    [TestCase("CITY", TestName = "A static field")]
+    [TestCase("ROOM", TestName = "A constant")]
+    [TestCase("Shorten(this.location)", TestName = "A static method")]
+    public async Task AMemberWhichNeedsNoThisIsLeftAlone(string expression)
+    {
+        var reported = await AnalyzeClassAsync(expression);
+
+        Assert.That(reported, Is.Empty);
+    }
+
+    [TestCase("location", TestName = "A field without this")]
+    [TestCase("Name", TestName = "A property without this")]
+    [TestCase("Describe()", TestName = "A method without this")]
+    public async Task AnInstanceMemberWithoutThisIsRefused(string expression)
+    {
+        var reported = await AnalyzeClassAsync(expression);
+
+        using (Assert.EnterMultipleScope())
+        {
+            Assert.That(reported, Has.Count.EqualTo(1));
+            Assert.That(reported.FirstOrDefault()?.Id, Is.EqualTo("MWAIS0005"));
+        }
+    }
+
+    [Test]
+    public async Task AClassicExtensionMethodIsLeftAlone()
+    {
+        var source =
+            """
+            namespace Sample;
+
+            public sealed class Meeting
+            {
+                public string Name { get; set; } = "Kickoff";
+            }
+
+            public static class MeetingExtensions
+            {
+                private static readonly string PREFIX = "Meeting: ";
+
+                public static string Label(this Meeting meeting) => PREFIX + meeting.Name;
+
+                public static string Title(this Meeting meeting) => Label(meeting).ToUpperInvariant();
+            }
+            """;
+
+        var reported = await CompilationHarness.AnalyzeAsync(source, new ThisUsageAnalyzer());
+
+        Assert.That(reported, Is.Empty);
+    }
+
+    [TestCase("public string Label() => meeting.Name;", TestName = "A member of the receiver")]
+    [TestCase("public string Label() => meeting.Title();", TestName = "A sibling through the receiver")]
+    [TestCase("public string Label() => Title(meeting);", TestName = "A sibling as a static method")]
+    [TestCase("""public string Label() => PREFIX + SUFFIX + TB("Meeting");""", TestName = "The static members of the class")]
+    [TestCase("public string Label() { System.Func<string> title = () => meeting.Title(); return title(); }", TestName = "A lambda")]
+    [TestCase("public string Label() { string Title() => meeting.Name; return Title(); }", TestName = "A local function")]
+    [TestCase("public string Label => meeting.Title();", TestName = "An extension property")]
+    [TestCase("public static Meeting Create() => new(); public static Meeting Again() => Create();", TestName = "A static member of the block")]
+    public async Task AMemberOfAnExtensionBlockIsLeftAlone(string member)
+    {
+        var source =
+            $$"""
+              namespace Sample;
+
+              public sealed class Meeting
+              {
+                  public string Name { get; set; } = "Kickoff";
+              }
+
+              public static class MeetingExtensions
+              {
+                  private const string SUFFIX = ".";
+
+                  private static readonly string PREFIX = "Meeting: ";
+
+                  private static string TB(string fallbackEN) => fallbackEN;
+
+                  extension(Meeting meeting)
+                  {
+                      public string Title() => meeting.Name;
+
+                      {{member}}
+                  }
+              }
+              """;
+
+        var reported = await CompilationHarness.AnalyzeAsync(source, new ThisUsageAnalyzer());
+
+        Assert.That(reported, Is.Empty);
+    }
+
+    private static async Task<IReadOnlyList<Diagnostic>> AnalyzeClassAsync(string expression)
+    {
+        var source =
+            $$"""
+              namespace Sample;
+
+              public sealed class Meeting
+              {
+                  private const string ROOM = "A";
+
+                  private static readonly string CITY = "Cologne";
+
+                  private readonly string location = "Town hall";
+
+                  public string Name { get; set; } = "Kickoff";
+
+                  public string Run() => {{expression}};
+
+                  private string Describe() => this.Name;
+
+                  private static string Shorten(string text) => text[..1];
+              }
+              """;
+
+        return await CompilationHarness.AnalyzeAsync(source, new ThisUsageAnalyzer());
+    }
+}