DocumentExtensions.cs

namespace NServiceBus.AzureFunctions.InProcess.Analyzer.Tests;

using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CodeActions;
using Microsoft.CodeAnalysis.CodeFixes;
using Microsoft.CodeAnalysis.Formatting;
using Microsoft.CodeAnalysis.Simplification;

static class DocumentExtensions
{
    public static async Task<IEnumerable<Diagnostic>> GetCompilerDiagnostics(this Document document, CancellationToken cancellationToken = default) =>
        (await document.GetSemanticModelAsync(cancellationToken))
        .GetDiagnostics(cancellationToken: cancellationToken)
        .Where(diagnostic => diagnostic.Severity != DiagnosticSeverity.Hidden)
        .OrderBy(diagnostic => diagnostic.Location.SourceSpan)
        .ThenBy(diagnostic => diagnostic.Id);

    public static async Task<(Document Document, CodeAction Action)[]> GetCodeActions(this Project project, CodeFixProvider codeFix, Diagnostic diagnostic, CancellationToken cancellationToken = default)
    {
        var actions = new List<(Document, CodeAction)>();
        foreach (var document in project.Documents)
        {
            var context = new CodeFixContext(document, diagnostic, (action, _) => actions.Add((document, action)), cancellationToken);
            await codeFix.RegisterCodeFixesAsync(context);
        }
        return actions.ToArray();
    }

    public static async Task<Document> ApplyChanges(this Document document, CodeAction codeAction, CancellationToken cancellationToken = default)
    {
        var operations = await codeAction.GetOperationsAsync(cancellationToken);
        var solution = operations.OfType<ApplyChangesOperation>().Single().ChangedSolution;
        return solution.GetDocument(document.Id);
    }

    public static async Task<string> GetCode(this Document document, CancellationToken cancellationToken = default)
    {
        var simplifiedDoc = await Simplifier.ReduceAsync(document, Simplifier.Annotation, cancellationToken: cancellationToken);
        var root = await simplifiedDoc.GetSyntaxRootAsync(cancellationToken);
        root = Formatter.Format(root, Formatter.Annotation, simplifiedDoc.Project.Solution.Workspace, cancellationToken: cancellationToken);
        return root.GetText().ToString();
    }
}