csharp-sdk/tests/ModelContextProtocol.Tests/Transport/StdioServerTransportTests.cs

using System.Text.Json;
using ModelContextProtocol.Protocol.Messages;
using ModelContextProtocol.Protocol.Transport;
using ModelContextProtocol.Protocol.Types;
using ModelContextProtocol.Server;
using ModelContextProtocol.Utils.Json;
using Microsoft.Extensions.Logging.Abstractions;

namespace ModelContextProtocol.Tests.Transport;

public class StdioServerTransportTests
{
    private readonly McpServerOptions _serverOptions;

    public StdioServerTransportTests()
    {
        _serverOptions = new McpServerOptions
        {
            ServerInfo = new Implementation
            {
                Name = "Test Server",
                Version = "1.0"
            },
            ProtocolVersion = "2.0",
            InitializationTimeout = TimeSpan.FromSeconds(10),
            ServerInstructions = "Test Instructions"
        };
    }

    [Fact]
    public async Task Constructor_Should_Initialize_With_Valid_Parameters()
    {
        // Act
        await using var transport = new StdioServerTransport(_serverOptions);

        // Assert
        Assert.NotNull(transport);
    }

    [Fact]
    public void Constructor_Throws_For_Null_Options()
    {
        Assert.Throws<ArgumentNullException>("serverName", () => new StdioServerTransport((string)null!));

        Assert.Throws<ArgumentNullException>("serverOptions", () => new StdioServerTransport((McpServerOptions)null!));
        Assert.Throws<ArgumentNullException>("serverOptions.ServerInfo", () => new StdioServerTransport(new McpServerOptions() { ServerInfo = null! }));
        Assert.Throws<ArgumentNullException>("serverName", () => new StdioServerTransport(new McpServerOptions() { ServerInfo = new() { Name = null!, Version = "" } }));
    }

    [Fact]
    public async Task StartListeningAsync_Should_Set_Connected_State()
    {
        await using var transport = new StdioServerTransport(_serverOptions);

        await transport.StartListeningAsync(TestContext.Current.CancellationToken);

        Assert.True(transport.IsConnected);
    }

    [Fact(Skip = "https://github.com/modelcontextprotocol/csharp-sdk/issues/1")]
    public async Task SendMessageAsync_Should_Send_Message()
    {
        TextReader oldIn = Console.In;
        TextWriter oldOut = Console.Out;
        try
        {
            using var output = new StringWriter();

            Console.SetIn(new StringReader(""));
            Console.SetOut(output);

            await using var transport = new StdioServerTransport(_serverOptions, NullLoggerFactory.Instance);
            await transport.StartListeningAsync(TestContext.Current.CancellationToken);

            var message = new JsonRpcRequest { Method = "test", Id = RequestId.FromNumber(44) };


            await transport.SendMessageAsync(message, TestContext.Current.CancellationToken);

            var result = output.ToString()?.Trim();
            var expected = JsonSerializer.Serialize(message, McpJsonUtilities.DefaultOptions);

            Assert.Equal(expected, result);
        }
        finally
        {
            Console.SetOut(oldOut);
            Console.SetIn(oldIn);
        }
    }

    [Fact]
    public async Task SendMessageAsync_Throws_Exception_If_Not_Connected()
    {
        await using var transport = new StdioServerTransport(_serverOptions);

        var message = new JsonRpcRequest { Method = "test" };

        await Assert.ThrowsAsync<McpTransportException>(() => transport.SendMessageAsync(message, TestContext.Current.CancellationToken));
    }

    [Fact]
    public async Task DisposeAsync_Should_Dispose_Resources()
    {
        await using var transport = new StdioServerTransport(_serverOptions);

        await transport.DisposeAsync();

        Assert.False(transport.IsConnected);
    }

    [Fact]
    public async Task ReadMessagesAsync_Should_Read_Messages()
    {
        var message = new JsonRpcRequest { Method = "test", Id = RequestId.FromNumber(44) };
        var json = JsonSerializer.Serialize(message, McpJsonUtilities.DefaultOptions);

        TextReader oldIn = Console.In;
        TextWriter oldOut = Console.Out;
        try
        {
            Console.SetIn(new StringReader(json));
            Console.SetOut(new StringWriter());

            await using var transport = new StdioServerTransport(_serverOptions);
            await transport.StartListeningAsync(TestContext.Current.CancellationToken);

            var canRead = await transport.MessageReader.WaitToReadAsync(TestContext.Current.CancellationToken);

            Assert.True(canRead, "Nothing to read here from transport message reader");
            Assert.True(transport.MessageReader.TryPeek(out var readMessage));
            Assert.NotNull(readMessage);
            Assert.IsType<JsonRpcRequest>(readMessage);
            Assert.Equal(44, ((JsonRpcRequest)readMessage).Id.AsNumber);
        }
        finally
        {
            Console.SetOut(oldOut);
            Console.SetIn(oldIn);
        }
    }

    [Fact]
    public async Task CleanupAsync_Should_Cleanup_Resources()
    {
        var transport = new StdioServerTransport(_serverOptions);
        await transport.StartListeningAsync(TestContext.Current.CancellationToken);

        await transport.DisposeAsync();

        Assert.False(transport.IsConnected);
    }
}