csharp-sdk/tests/ModelContextProtocol.AspNetCore.Tests/StatelessServerTests.cs

using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.DependencyInjection;
using ModelContextProtocol.AspNetCore.Tests.Utils;
using ModelContextProtocol.Client;
using ModelContextProtocol.Protocol;
using ModelContextProtocol.Server;
using System.Diagnostics;
using System.Net;

namespace ModelContextProtocol.AspNetCore.Tests;

[McpServerToolType]
public class StatelessServerTests(ITestOutputHelper outputHelper) : KestrelInMemoryTest(outputHelper), IAsyncDisposable
{
    private WebApplication? _app;

    private readonly SseClientTransportOptions DefaultTransportOptions = new()
    {
        Endpoint = new Uri("http://localhost/"),
        Name = "In-memory Streamable HTTP Client",
        UseStreamableHttp = true,
    };

    private async Task StartAsync()
    {
        Builder.Services.AddMcpServer(mcpServerOptions =>
            {
                mcpServerOptions.ServerInfo = new Implementation
                {
                    Name = nameof(StreamableHttpServerConformanceTests),
                    Version = "73",
                };
            })
            .WithHttpTransport(httpServerTransportOptions =>
            {
                httpServerTransportOptions.Stateless = true;
            })
            .WithTools<StatelessServerTests>();

        Builder.Services.AddScoped<ScopedService>();

        _app = Builder.Build();

        _app.Use(next =>
        {
            return context =>
            {
                context.RequestServices.GetRequiredService<ScopedService>().State = "From request middleware!";
                return next(context);
            };
        });

        _app.MapMcp();

        await _app.StartAsync(TestContext.Current.CancellationToken);

        HttpClient.DefaultRequestHeaders.Accept.Add(new("application/json"));
        HttpClient.DefaultRequestHeaders.Accept.Add(new("text/event-stream"));
    }

    private Task<IMcpClient> ConnectMcpClientAsync(McpClientOptions? clientOptions = null)
        => McpClientFactory.CreateAsync(
            new SseClientTransport(DefaultTransportOptions, HttpClient, LoggerFactory),
            clientOptions, LoggerFactory, TestContext.Current.CancellationToken);

    public async ValueTask DisposeAsync()
    {
        if (_app is not null)
        {
            await _app.DisposeAsync();
        }
        base.Dispose();
    }

    [Fact]
    public async Task EnablingStatelessMode_Disables_SseEndpoints()
    {
        await StartAsync();

        using var sseResponse = await HttpClient.GetAsync("/sse", TestContext.Current.CancellationToken);
        Assert.Equal(HttpStatusCode.NotFound, sseResponse.StatusCode);

        using var messageResponse = await HttpClient.PostAsync("/message", new StringContent(""), TestContext.Current.CancellationToken);
        Assert.Equal(HttpStatusCode.NotFound, messageResponse.StatusCode);
    }

    [Fact]
    public async Task EnablingStatelessMode_Disables_GetAndDeleteEndpoints()
    {
        await StartAsync();

        using var getResponse = await HttpClient.GetAsync("/", TestContext.Current.CancellationToken);
        Assert.Equal(HttpStatusCode.MethodNotAllowed, getResponse.StatusCode);

        using var deleteResponse = await HttpClient.DeleteAsync("/", TestContext.Current.CancellationToken);
        Assert.Equal(HttpStatusCode.MethodNotAllowed, deleteResponse.StatusCode);
    }

    [Fact]
    public async Task SamplingRequest_Fails_WithInvalidOperationException()
    {
        await StartAsync();

        var mcpClientOptions = new McpClientOptions();
        mcpClientOptions.Capabilities = new();
        mcpClientOptions.Capabilities.Sampling ??= new();
        mcpClientOptions.Capabilities.Sampling.SamplingHandler = (_, _, _) =>
        {
            throw new UnreachableException();
        };

        await using var client = await ConnectMcpClientAsync(mcpClientOptions);

        var toolResponse = await client.CallToolAsync("testSamplingErrors", cancellationToken: TestContext.Current.CancellationToken);
        var toolContent = Assert.Single(toolResponse.Content);
        Assert.Equal("Server to client requests are not supported in stateless mode.", toolContent.Text);
    }

    [Fact]
    public async Task RootsRequest_Fails_WithInvalidOperationException()
    {
        await StartAsync();

        var mcpClientOptions = new McpClientOptions();
        mcpClientOptions.Capabilities = new();
        mcpClientOptions.Capabilities.Roots ??= new();
        mcpClientOptions.Capabilities.Roots.RootsHandler = (_, _) =>
        {
            throw new UnreachableException();
        };

        await using var client = await ConnectMcpClientAsync(mcpClientOptions);

        var toolResponse = await client.CallToolAsync("testRootsErrors", cancellationToken: TestContext.Current.CancellationToken);
        var toolContent = Assert.Single(toolResponse.Content);
        Assert.Equal("Server to client requests are not supported in stateless mode.", toolContent.Text);
    }

    [Fact]
    public async Task UnsolicitedNotification_Fails_WithInvalidOperationException()
    {
        InvalidOperationException? unsolicitedNotificationException = null;

        Builder.Services.AddMcpServer()
            .WithHttpTransport(options =>
            {
                options.RunSessionHandler = async (context, server, cancellationToken) =>
                {
                    unsolicitedNotificationException = await Assert.ThrowsAsync<InvalidOperationException>(
                        () => server.SendNotificationAsync(NotificationMethods.PromptListChangedNotification, TestContext.Current.CancellationToken));

                    await server.RunAsync(cancellationToken);
                };
            });

        await StartAsync();

        await using var client = await ConnectMcpClientAsync();

        Assert.NotNull(unsolicitedNotificationException);
        Assert.Equal("Unsolicited server to client messages are not supported in stateless mode.", unsolicitedNotificationException.Message);
    }

    [Fact]
    public async Task ScopedServices_Resolve_FromRequestScope()
    {
        await StartAsync();

        await using var client = await ConnectMcpClientAsync();

        var toolResponse = await client.CallToolAsync("testScope", cancellationToken: TestContext.Current.CancellationToken);
        var toolContent = Assert.Single(toolResponse.Content);
        Assert.Equal("From request middleware!", toolContent.Text);
    }

    [McpServerTool(Name = "testSamplingErrors")]
    public static async Task<string> TestSamplingErrors(IMcpServer server)
    {
        const string expectedSamplingErrorMessage = "Sampling is not supported in stateless mode.";

        // Even when the client has sampling support, it should not be advertised in stateless mode.
        Assert.Null(server.ClientCapabilities);

        var asSamplingChatClientEx = Assert.Throws<InvalidOperationException>(() => server.AsSamplingChatClient());
        Assert.Equal(expectedSamplingErrorMessage, asSamplingChatClientEx.Message);

        var requestSamplingEx = await Assert.ThrowsAsync<InvalidOperationException>(() => server.RequestSamplingAsync([]));
        Assert.Equal(expectedSamplingErrorMessage, requestSamplingEx.Message);

        var ex = await Assert.ThrowsAsync<InvalidOperationException>(() => server.SendRequestAsync(new JsonRpcRequest { Method = RequestMethods.SamplingCreateMessage }));
        return ex.Message;
    }

    [McpServerTool(Name = "testRootsErrors")]
    public static async Task<string> TestRootsErrors(IMcpServer server)
    {
        const string expectedRootsErrorMessage = "Roots are not supported in stateless mode.";

        // Even when the client has roots support, it should not be advertised in stateless mode.
        Assert.Null(server.ClientCapabilities);

        var requestRootsEx = Assert.Throws<InvalidOperationException>(() => server.RequestRootsAsync(new()));
        Assert.Equal(expectedRootsErrorMessage, requestRootsEx.Message);

        var ex = await Assert.ThrowsAsync<InvalidOperationException>(() => server.SendRequestAsync(new JsonRpcRequest { Method = RequestMethods.RootsList }));
        return ex.Message;
    }

    [McpServerTool(Name = "testScope")]
    public static string? TestScope(ScopedService scopedService) => scopedService.State;

    public class ScopedService
    {
        public string? State { get; set; }
    }
}