CompilationExtensions.cs

namespace NServiceBus.AzureFunctions.InProcess.Analyzer.Tests;

using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.Diagnostics;

static class CompilationExtensions
{
    public static void Compile(this Compilation compilation, bool throwOnFailure = true)
    {
        using (var peStream = new MemoryStream())
        {
            var emitResult = compilation.Emit(peStream);

            if (!emitResult.Success)
            {
                if (throwOnFailure)
                {
                    throw new Exception("Compilation failed.");
                }
                else
                {
                    Debug.WriteLine("Compilation failed.");
                }
            }
        }
    }

    public static async Task<IEnumerable<Diagnostic>> GetAnalyzerDiagnostics(this Compilation compilation, DiagnosticAnalyzer analyzer, CancellationToken cancellationToken = default)
    {
        var exceptions = new List<Exception>();

        var analysisOptions = new CompilationWithAnalyzersOptions(
            new AnalyzerOptions(ImmutableArray<AdditionalText>.Empty),
            (exception, _, __) => exceptions.Add(exception),
            concurrentAnalysis: false,
            logAnalyzerExecutionTime: false);

        var diagnostics = await compilation
            .WithAnalyzers([analyzer], analysisOptions)
            .GetAnalyzerDiagnosticsAsync(cancellationToken);

        if (exceptions.Any())
        {
            throw new AggregateException(exceptions);
        }

        return diagnostics
            .OrderBy(diagnostic => diagnostic.Location.SourceSpan)
            .ThenBy(diagnostic => diagnostic.Id);
    }
}