Add suppressor for CA1515 (#182)

src/xunit.analyzers.tests/Suppressors/MakeTypesInternalSuppressorTests.cs

@@ -0,0 +1,66 @@
+#if NETCOREAPP
+
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Testing;
+using Xunit;
+using Xunit.Analyzers;
+using Verify = CSharpVerifier<Xunit.Suppressors.MakeTypesInternalSuppressor>;
+
+#if !ROSLYN_3_11
+using System;
+#endif
+
+public sealed class MakeTypesInternalSuppressorTests
+{
+	[Fact]
+	public async Task NonTestClass_DoesNotSuppress()
+	{
+		var code = @"
+public class NonTestClass {
+    public void NonTestMethod() { }
+}";
+
+		var expected =
+			new DiagnosticResult("CA1515", DiagnosticSeverity.Warning)
+				.WithSpan(2, 14, 2, 26)
+				.WithIsSuppressed(false);
+
+		await Verify.VerifySuppressor(code, CodeAnalysisNetAnalyzers.CA1515(), expected);
+	}
+
+	[Theory]
+	[InlineData("Fact")]
+	[InlineData("FactAttribute")]
+	[InlineData("Theory")]
+	[InlineData("TheoryAttribute")]
+	[InlineData("CustomFact")]
+	[InlineData("CustomFactAttribute")]
+	public async Task TestClass_Suppresses(string attribute)
+	{
+		var code = @$"
+using Xunit;
+
+internal class CustomFactAttribute : FactAttribute {{ }}
+
+public class TestClass {{
+    [{attribute}]
+    public void TestMethod() {{ }}
+}}";
+
+#if ROSLYN_3_11
+		// Roslyn 3.11 still surfaces the diagnostic that has been suppressed
+		var expected =
+			new DiagnosticResult("CA1515", DiagnosticSeverity.Warning)
+				.WithSpan(6, 14, 6, 23)
+				.WithIsSuppressed(true);
+#else
+		// Later versions of Roslyn just removes it from the results
+		var expected = Array.Empty<DiagnosticResult>();
+#endif
+
+		await Verify.VerifySuppressor(code, CodeAnalysisNetAnalyzers.CA1515(), expected);
+	}
+}
+
+#endif

src/xunit.analyzers.tests/Utility/CodeAnalysisNetAnalyzers.cs

@@ -0,0 +1,46 @@
+#if NETCOREAPP
+
+using System;
+using System.IO;
+using System.Reflection;
+using System.Runtime.InteropServices;
+using System.Runtime.Loader;
+using Microsoft.CodeAnalysis.Diagnostics;
+
+namespace Xunit.Analyzers;
+
+public static class CodeAnalysisNetAnalyzers
+{
+	public static Lazy<Assembly> assembly = new(LoadAssembly, isThreadSafe: true);
+	public static Lazy<Type> typeCA1515 = new(() => FindType("Microsoft.CodeQuality.CSharp.Analyzers.Maintainability.CSharpMakeTypesInternal"), isThreadSafe: true);
+
+	public static DiagnosticAnalyzer CA1515() =>
+		Activator.CreateInstance(typeCA1515.Value) as DiagnosticAnalyzer ?? throw new InvalidOperationException($"Could not create instance of '{typeCA1515.Value.FullName}'");
+
+	static Type FindType(string typeName) =>
+		assembly.Value.GetType(typeName) ?? throw new InvalidOperationException($"Could not locate type '{typeName}' from Microsoft.CodeAnalysis.NetAnalyzers");
+
+	static Assembly LoadAssembly()
+	{
+		var nugetPackagesFolder = Environment.GetEnvironmentVariable("NUGET_PACKAGES");
+		if (nugetPackagesFolder is null)
+		{
+			var homeFolder =
+				RuntimeInformation.IsOSPlatform(OSPlatform.Windows)
+					? Environment.GetEnvironmentVariable("USERPROFILE")
+					: Environment.GetEnvironmentVariable("HOME");
+
+			nugetPackagesFolder = Path.Combine(homeFolder ?? throw new InvalidOperationException("Could not determine home folder"), ".nuget", "packages");
+		}
+
+		if (!Directory.Exists(nugetPackagesFolder))
+			throw new InvalidOperationException($"NuGet package cache folder '{nugetPackagesFolder}' does not exist");
+
+		var loadContext = AssemblyLoadContext.Default;
+		loadContext.LoadFromAssemblyPath(Path.Combine(nugetPackagesFolder, "microsoft.codeanalysis.workspaces.common", "3.11.0", "lib", "netcoreapp3.1", "Microsoft.CodeAnalysis.Workspaces.dll"));
+		loadContext.LoadFromAssemblyPath(Path.Combine(nugetPackagesFolder, "microsoft.codeanalysis.netanalyzers", "9.0.0-preview.24072.1", "analyzers", "dotnet", "cs", "Microsoft.CodeAnalysis.NetAnalyzers.dll"));
+		return loadContext.LoadFromAssemblyPath(Path.Combine(nugetPackagesFolder, "microsoft.codeanalysis.netanalyzers", "9.0.0-preview.24072.1", "analyzers", "dotnet", "cs", "Microsoft.CodeAnalysis.CSharp.NetAnalyzers.dll"));
+	}
+}
+
+#endif

src/xunit.analyzers.tests/xunit.analyzers.tests.csproj

@@ -18,6 +18,10 @@
     <PackageDownload Include="xunit.v3.common" Version="[0.1.1-pre.350]" />
     <PackageDownload Include="xunit.v3.extensibility.core" Version="[0.1.1-pre.350]" />
     <PackageDownload Include="xunit.v3.runner.utility" Version="[0.1.1-pre.350]" />
+
+    <!-- Download packages referenced by CodeAnalysisNetAnalyzers -->
+    <PackageDownload Include="Microsoft.CodeAnalysis.NetAnalyzers" Version="[9.0.0-preview.24072.1]" />
+    <PackageDownload Include="Microsoft.CodeAnalysis.Workspaces.Common" Version="[3.11.0]" />
   </ItemGroup>
 
   <ItemGroup>

src/xunit.analyzers/Suppressors/MakeTypesInternalSuppressor.cs

@@ -0,0 +1,31 @@
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Diagnostics;
+using Xunit.Analyzers;
+
+namespace Xunit.Suppressors;
+
+[DiagnosticAnalyzer(LanguageNames.CSharp)]
+public sealed class MakeTypesInternalSuppressor : XunitDiagnosticSuppressor
+{
+	public MakeTypesInternalSuppressor() :
+		base(Descriptors.CA1515_Suppression)
+	{ }
+
+	protected override bool ShouldSuppress(
+		Diagnostic diagnostic,
+		SuppressionAnalysisContext context,
+		XunitContext xunitContext)
+	{
+		if (diagnostic.Location.SourceTree is null)
+			return false;
+
+		var root = diagnostic.Location.SourceTree.GetRoot(context.CancellationToken);
+		if (root?.FindNode(diagnostic.Location.SourceSpan) is not ClassDeclarationSyntax classDeclaration)
+			return false;
+
+		var semanticModel = context.GetSemanticModel(diagnostic.Location.SourceTree);
+		var classSymbol = semanticModel.GetDeclaredSymbol(classDeclaration) as ITypeSymbol;
+		return classSymbol.IsTestClass(xunitContext, strict: false);
+	}
+}

src/xunit.analyzers/Utility/CodeAnalysisExtensions.cs

@@ -73,12 +73,45 @@ public static bool IsInTestMethod(
 	}
 
 	public static bool IsTestClass(
-		this ITypeSymbol type,
-		XunitContext xunitContext)
+		this ITypeSymbol? type,
+		XunitContext xunitContext,
+		bool strict)
 	{
-		Guard.ArgumentNotNull(type);
 		Guard.ArgumentNotNull(xunitContext);
 
+		if (type is null)
+			return false;
+
+		if (strict)
+			return IsTestClassStrict(type, xunitContext);
+		else
+			return IsTestClassNonStrict(type, xunitContext);
+	}
+
+	static bool IsTestClassNonStrict(
+		ITypeSymbol type,
+		XunitContext xunitContext)
+	{
+		var factAttributeType = xunitContext.Core.FactAttributeType;
+		if (factAttributeType is null)
+			return false;
+
+		return
+			type
+				.GetMembers()
+				.OfType<IMethodSymbol>()
+				.Any(method =>
+					method
+						.GetAttributes()
+						.Select(a => a.AttributeClass)
+						.Any(t => factAttributeType.IsAssignableFrom(t))
+				);
+	}
+
+	static bool IsTestClassStrict(
+		ITypeSymbol type,
+		XunitContext xunitContext)
+	{
 		var factAttributeType = xunitContext.Core.FactAttributeType;
 		var theoryAttributeType = xunitContext.Core.TheoryAttributeType;
 		if (factAttributeType is null || theoryAttributeType is null)

src/xunit.analyzers/Utility/Descriptors.Suppressors.cs

@@ -1,5 +1,9 @@
+using Microsoft.CodeAnalysis;
+
 namespace Xunit.Analyzers;
 
 public static partial class Descriptors
 {
+	public static SuppressionDescriptor CA1515_Suppression { get; } =
+		Suppression("CA1515", "xUnit.net's test classes must be public.");
 }

src/xunit.analyzers/Utility/XunitDiagnosticSuppressor.cs

@@ -1,8 +1,9 @@
 using System.Collections.Immutable;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Diagnostics;
+using Xunit.Analyzers;
 
-namespace Xunit.Analyzers;
+namespace Xunit.Suppressors;
 
 /// <summary>
 /// Base class for diagnostic suppressors which support xUnit.net v2 and v3.

src/xunit.analyzers/Utility/XunitV2DiagnosticSuppressor.cs

@@ -1,6 +1,7 @@
 using Microsoft.CodeAnalysis;
+using Xunit.Analyzers;
 
-namespace Xunit.Analyzers;
+namespace Xunit.Suppressors;
 
 /// <summary>
 /// Base class for diagnostic suppressors which support xUnit.net v2 only.

src/xunit.analyzers/Utility/XunitV3DiagnosticSuppressor.cs

@@ -1,6 +1,7 @@
 using Microsoft.CodeAnalysis;
+using Xunit.Analyzers;
 
-namespace Xunit.Analyzers;
+namespace Xunit.Suppressors;
 
 /// <summary>
 /// Base class for diagnostic suppressors which support xUnit.net v3 only.

src/xunit.analyzers/X1000/EnsureFixturesHaveASource.cs

@@ -30,7 +30,7 @@ public override void AnalyzeCompilation(
 				return;
 			if (namedType.IsAbstract)
 				return;
-			if (!namedType.IsTestClass(xunitContext))
+			if (!namedType.IsTestClass(xunitContext, strict: true))
 				return;
 
 			// Only evaluate if there's a single public constructor