git.stella-ops.org/src/AirGap/StellaOps.AirGap.Policy/StellaOps.AirGap.Policy.Analyzers.Tests/HttpClientUsageAnalyzerTests.cs

using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Linq;
using System.Net.Http;
using System.Reflection;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CodeActions;
using Microsoft.CodeAnalysis.CodeFixes;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.Diagnostics;
using Microsoft.CodeAnalysis.Text;
using Xunit;


using StellaOps.TestKit;
namespace StellaOps.AirGap.Policy.Analyzers.Tests;

public sealed class HttpClientUsageAnalyzerTests
{
    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public async Task ReportsDiagnostic_ForNewHttpClient()
    {
        const string source = """
            using System.Net.Http;

            namespace Sample.App;

            public sealed class Demo
            {
                public void Run()
                {
                    var client = new HttpClient();
                }
            }
            """;

        var diagnostics = await AnalyzeAsync(source, assemblyName: "Sample.App");
        Assert.Contains(diagnostics, d => d.Id == HttpClientUsageAnalyzer.DiagnosticId);
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public async Task DoesNotReportDiagnostic_InsidePolicyAssembly()
    {
        const string source = """
            using System.Net.Http;

            namespace StellaOps.AirGap.Policy.Internal;

            internal static class Loopback
            {
                public static HttpClient Create() => new HttpClient();
            }
            """;

        var diagnostics = await AnalyzeAsync(source, assemblyName: "StellaOps.AirGap.Policy");
        Assert.DoesNotContain(diagnostics, d => d.Id == HttpClientUsageAnalyzer.DiagnosticId);
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public async Task DoesNotReportDiagnostic_ForTestingAssemblyNames()
    {
        const string source = """
            using System.Net.Http;

            namespace Sample.App;

            public sealed class Demo
            {
                public void Run()
                {
                    var client = new HttpClient();
                }
            }
            """;

        var diagnostics = await AnalyzeAsync(source, assemblyName: "Sample.App.Testing");
        Assert.DoesNotContain(diagnostics, d => d.Id == HttpClientUsageAnalyzer.DiagnosticId);
    }

    private static async Task<ImmutableArray<Diagnostic>> AnalyzeAsync(string source, string assemblyName)
    {
        var compilation = CSharpCompilation.Create(
            assemblyName,
            new[]
            {
                CSharpSyntaxTree.ParseText(source),
                CSharpSyntaxTree.ParseText(PolicyStubSource),
            },
            CreateMetadataReferences(),
            new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary));

        var analyzer = new HttpClientUsageAnalyzer();
        var compilationWithAnalyzers = compilation.WithAnalyzers(ImmutableArray.Create<DiagnosticAnalyzer>(analyzer));
        return await compilationWithAnalyzers.GetAnalyzerDiagnosticsAsync();
    }

    private static IEnumerable<MetadataReference> CreateMetadataReferences()
    {
        yield return MetadataReference.CreateFromFile(typeof(object).GetTypeInfo().Assembly.Location);
        yield return MetadataReference.CreateFromFile(typeof(Uri).GetTypeInfo().Assembly.Location);
        yield return MetadataReference.CreateFromFile(typeof(HttpClient).GetTypeInfo().Assembly.Location);
        yield return MetadataReference.CreateFromFile(typeof(Enumerable).GetTypeInfo().Assembly.Location);
    }

    private const string PolicyStubSource = """
        namespace StellaOps.AirGap.Policy
        {
            public interface IEgressPolicy
            {
                void EnsureAllowed(EgressRequest request);
            }

            public readonly record struct EgressRequest(string Component, System.Uri Destination, string Intent);

            public static class EgressHttpClientFactory
            {
                public static System.Net.Http.HttpClient Create(IEgressPolicy egressPolicy, EgressRequest request)
                    => throw new System.NotImplementedException();

                public static System.Net.Http.HttpClient Create(IEgressPolicy egressPolicy, EgressRequest request, System.Func<System.Net.Http.HttpClient> clientFactory)
                    => throw new System.NotImplementedException();
            }
        }
        """;
}