Extract helpers to AsyncHelper, and sort AssertThrowsShouldNotBeUsedF…

…orAsyncThrowsCheckFixer members

src/xunit.analyzers.fixes/Utility/AsyncHelper.cs

@@ -0,0 +1,49 @@
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Editing;
+using static Microsoft.CodeAnalysis.CSharp.SyntaxFactory;
+
+namespace Xunit.Analyzers.Fixes;
+
+public static class AsyncHelper
+{
+	/// <summary>
+	/// Get a method's modifiers that include the async keyword.
+	/// </summary>
+	public static SyntaxTokenList GetModifiersWithAsyncKeywordAdded(MethodDeclarationSyntax method) =>
+		method.Modifiers.Any(SyntaxKind.AsyncKeyword)
+			? method.Modifiers
+			: method.Modifiers.Add(Token(SyntaxKind.AsyncKeyword));
+
+	/// <summary>
+	/// Get the syntax type for an updated return type to support using async.
+	/// </summary>
+	public static async Task<TypeSyntax?> GetReturnType(
+		MethodDeclarationSyntax method,
+		InvocationExpressionSyntax invocation,
+		Document document,
+		DocumentEditor editor,
+		CancellationToken cancellationToken)
+	{
+		// Consider the case where a custom awaiter type is awaited
+		if (invocation.Parent.IsKind(SyntaxKind.AwaitExpression))
+			return method.ReturnType;
+
+		var semanticModel = await document.GetSemanticModelAsync(cancellationToken).ConfigureAwait(false);
+		if (semanticModel is null)
+			return null;
+
+		var methodSymbol = semanticModel.GetSymbolInfo(method.ReturnType, cancellationToken).Symbol as ITypeSymbol;
+		var taskType = TypeSymbolFactory.Task(semanticModel.Compilation);
+		if (taskType is null)
+			return null;
+
+		if (taskType.IsAssignableFrom(methodSymbol))
+			return method.ReturnType;
+
+		return editor.Generator.TypeExpression(taskType) as TypeSyntax;
+	}
+}

src/xunit.analyzers.fixes/X2000/AssertThrowsShouldNotBeUsedForAsyncThrowsCheckFixer.cs

@@ -21,6 +21,34 @@ public AssertThrowsShouldNotBeUsedForAsyncThrowsCheckFixer() :
 		base(Descriptors.X2014_AssertThrowsShouldNotBeUsedForAsyncThrowsCheck.Id)
 	{ }
 
+	static ExpressionSyntax GetAsyncThrowsInvocation(
+		InvocationExpressionSyntax invocation,
+		string memberName,
+		MemberAccessExpressionSyntax memberAccess)
+	{
+		var asyncThrowsInvocation =
+			invocation
+				.WithExpression(memberAccess.WithName(GetName(memberName, memberAccess)))
+				.WithArgumentList(invocation.ArgumentList);
+
+		if (invocation.Parent.IsKind(SyntaxKind.AwaitExpression))
+			return asyncThrowsInvocation;
+
+		return
+			AwaitExpression(asyncThrowsInvocation.WithoutLeadingTrivia())
+				.WithLeadingTrivia(invocation.GetLeadingTrivia());
+	}
+
+	static SimpleNameSyntax GetName(
+		string memberName,
+		MemberAccessExpressionSyntax memberAccess)
+	{
+		if (memberAccess.Name is not GenericNameSyntax genericNameSyntax)
+			return IdentifierName(memberName);
+
+		return GenericName(IdentifierName(memberName).Identifier, genericNameSyntax.TypeArgumentList);
+	}
+
 	public sealed override async Task RegisterCodeFixesAsync(CodeFixContext context)
 	{
 		var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
@@ -66,8 +94,8 @@ static async Task<Document> UseAsyncThrowsCheck(
 
 		if (invocation.Expression is MemberAccessExpressionSyntax memberAccess)
 		{
-			var modifiers = GetModifiersWithAsyncKeywordAdded(method);
-			var returnType = await GetReturnType(method, invocation, document, editor, cancellationToken);
+			var modifiers = AsyncHelper.GetModifiersWithAsyncKeywordAdded(method);
+			var returnType = await AsyncHelper.GetReturnType(method, invocation, document, editor, cancellationToken);
 			var asyncThrowsInvocation = GetAsyncThrowsInvocation(invocation, replacement, memberAccess);
 
 			if (returnType is not null)
@@ -82,63 +110,4 @@ static async Task<Document> UseAsyncThrowsCheck(
 
 		return editor.GetChangedDocument();
 	}
-
-	static SyntaxTokenList GetModifiersWithAsyncKeywordAdded(MethodDeclarationSyntax method) =>
-		method.Modifiers.Any(SyntaxKind.AsyncKeyword)
-			? method.Modifiers
-			: method.Modifiers.Add(Token(SyntaxKind.AsyncKeyword));
-
-	static async Task<TypeSyntax?> GetReturnType(
-		MethodDeclarationSyntax method,
-		InvocationExpressionSyntax invocation,
-		Document document,
-		DocumentEditor editor,
-		CancellationToken cancellationToken)
-	{
-		// Consider the case where a custom awaiter type is awaited
-		if (invocation.Parent.IsKind(SyntaxKind.AwaitExpression))
-			return method.ReturnType;
-
-		var semanticModel = await document.GetSemanticModelAsync(cancellationToken).ConfigureAwait(false);
-		if (semanticModel is null)
-			return null;
-
-		var methodSymbol = semanticModel.GetSymbolInfo(method.ReturnType, cancellationToken).Symbol as ITypeSymbol;
-		var taskType = TypeSymbolFactory.Task(semanticModel.Compilation);
-		if (taskType is null)
-			return null;
-
-		if (taskType.IsAssignableFrom(methodSymbol))
-			return method.ReturnType;
-
-		return editor.Generator.TypeExpression(taskType) as TypeSyntax;
-	}
-
-	static ExpressionSyntax GetAsyncThrowsInvocation(
-		InvocationExpressionSyntax invocation,
-		string memberName,
-		MemberAccessExpressionSyntax memberAccess)
-	{
-		var asyncThrowsInvocation =
-			invocation
-				.WithExpression(memberAccess.WithName(GetName(memberName, memberAccess)))
-				.WithArgumentList(invocation.ArgumentList);
-
-		if (invocation.Parent.IsKind(SyntaxKind.AwaitExpression))
-			return asyncThrowsInvocation;
-
-		return
-			AwaitExpression(asyncThrowsInvocation.WithoutLeadingTrivia())
-				.WithLeadingTrivia(invocation.GetLeadingTrivia());
-	}
-
-	static SimpleNameSyntax GetName(
-		string memberName,
-		MemberAccessExpressionSyntax memberAccess)
-	{
-		if (memberAccess.Name is not GenericNameSyntax genericNameSyntax)
-			return IdentifierName(memberName);
-
-		return GenericName(IdentifierName(memberName).Identifier, genericNameSyntax.TypeArgumentList);
-	}
 }