csharp-sdk/tests/ModelContextProtocol.Tests/Client/McpClientFactoryTests.cs

using Microsoft.Extensions.Logging;
using ModelContextProtocol.Client;
using ModelContextProtocol.Protocol.Messages;
using ModelContextProtocol.Protocol.Transport;
using ModelContextProtocol.Protocol.Types;
using Moq;
using System.Text.Json;
using System.Threading.Channels;

namespace ModelContextProtocol.Tests.Client;

public class McpClientFactoryTests
{
    private readonly McpClientOptions _defaultOptions = new()
    {
        ClientInfo = new() { Name = "TestClient", Version = "1.0.0" }
    };

    [Fact]
    public async Task CreateAsync_WithInvalidArgs_Throws()
    {
        await Assert.ThrowsAsync<ArgumentNullException>("serverConfig", () => McpClientFactory.CreateAsync((McpServerConfig)null!, _defaultOptions, cancellationToken: TestContext.Current.CancellationToken));

        await Assert.ThrowsAsync<ArgumentException>("serverConfig", () => McpClientFactory.CreateAsync(new McpServerConfig()
            {
                Name = "name",
                Id = "id",
                TransportType = "somethingunsupported",
            }, _defaultOptions, cancellationToken: TestContext.Current.CancellationToken));

        await Assert.ThrowsAsync<InvalidOperationException>(() => McpClientFactory.CreateAsync(new McpServerConfig()
            {
                Name = "name",
                Id = "id",
                TransportType = TransportTypes.StdIo,
            }, _defaultOptions, (_, __) => null!, cancellationToken: TestContext.Current.CancellationToken));
    }

    [Fact]
    public async Task CreateAsync_NullOptions_EntryAssemblyInferred()
    {
        // Arrange
        var serverConfig = new McpServerConfig
        {
            Id = "test-server",
            Name = "Test Server",
            TransportType = TransportTypes.StdIo,
            Location = "/path/to/server",
        };

        // Act
        await using var client = await McpClientFactory.CreateAsync(
            serverConfig,
            null,
            (_, __) => new NopTransport(),
            cancellationToken: TestContext.Current.CancellationToken);

        Assert.NotNull(client);
    }

    [Fact]
    public async Task CreateAsync_WithValidStdioConfig_CreatesNewClient()
    {
        // Arrange
        var serverConfig = new McpServerConfig
        {
            Id = "test-server",
            Name = "Test Server",
            TransportType = TransportTypes.StdIo,
            Location = "/path/to/server",
            TransportOptions = new Dictionary<string, string>
            {
                ["arguments"] = "--test arg",
                ["workingDirectory"] = "/working/dir"
            }
        };

        // Act
        await using var client = await McpClientFactory.CreateAsync(
            serverConfig,
            _defaultOptions,
            (_, __) => new NopTransport(),
            cancellationToken: TestContext.Current.CancellationToken);

        // Assert
        Assert.NotNull(client);
        // We could add more assertions here about the client's configuration
    }

    [Fact]
    public async Task CreateAsync_WithNoTransportOptions_CreatesNewClient()
    {
        // Arrange
        var serverConfig = new McpServerConfig
        {
            Id = "test-server",
            Name = "Test Server",
            TransportType = TransportTypes.StdIo,
            Location = "/path/to/server",
        };

        // Act
        await using var client = await McpClientFactory.CreateAsync(
            serverConfig,
            _defaultOptions,
            (_, __) => new NopTransport(),
            cancellationToken: TestContext.Current.CancellationToken);

        // Assert
        Assert.NotNull(client);
        // We could add more assertions here about the client's configuration
    }

    [Fact]
    public async Task CreateAsync_WithValidSseConfig_CreatesNewClient()
    {
        // Arrange
        var serverConfig = new McpServerConfig
        {
            Id = "test-server",
            Name = "Test Server",
            TransportType = TransportTypes.Sse,
            Location = "http://localhost:8080"
        };

        // Act
        await using var client = await McpClientFactory.CreateAsync(
            serverConfig,
            _defaultOptions,
            (_, __) => new NopTransport(),
            cancellationToken: TestContext.Current.CancellationToken);

        // Assert
        Assert.NotNull(client);
        // We could add more assertions here about the client's configuration
    }

    [Fact]
    public async Task CreateAsync_WithSse_CreatesCorrectTransportOptions()
    {
        // Arrange
        var serverConfig = new McpServerConfig
        {
            Id = "test-server",
            Name = "Test Server",
            TransportType = TransportTypes.Sse,
            Location = "http://localhost:8080",
            TransportOptions = new Dictionary<string, string>
            {
                ["connectionTimeout"] = "10",
                ["maxReconnectAttempts"] = "2",
                ["reconnectDelay"] = "5",
                ["header.test"] = "the_header_value"
            }
        };

        // Act
        await using var client = await McpClientFactory.CreateAsync(
            serverConfig,
            _defaultOptions,
            (_, __) => new NopTransport(),
            cancellationToken: TestContext.Current.CancellationToken);

        // Assert
        Assert.NotNull(client);
        // We could add more assertions here about the client's configuration
    }

    [Theory]
    [InlineData("connectionTimeout", "not_a_number")]
    [InlineData("maxReconnectAttempts", "invalid")]
    [InlineData("reconnectDelay", "bad_value")]
    public async Task McpFactory_WithInvalidTransportOptions_ThrowsFormatException(string key, string value)
    {
        // arrange
        var config = new McpServerConfig
        {
            Id = "test-server",
            Name = "Test Server",
            TransportType = TransportTypes.Sse,
            Location = "http://localhost:8080",
            TransportOptions = new Dictionary<string, string>
            {
                [key] = value
            }
        };

        // act & assert
        await Assert.ThrowsAsync<ArgumentException>(() => McpClientFactory.CreateAsync(config, _defaultOptions, cancellationToken: TestContext.Current.CancellationToken));
    }

    [Theory]
    [InlineData(typeof(NopTransport))]
    [InlineData(typeof(FailureTransport))]
    public async Task CreateAsync_WithCapabilitiesOptions(Type transportType)
    {
        // Arrange
        var serverConfig = new McpServerConfig
        {
            Id = "TestServer",
            Name = "TestServer",
            TransportType = "stdio",
            Location = "test-location"
        };

        var clientOptions = new McpClientOptions
        {
            ClientInfo = new Implementation 
            {
                Name = "TestClient", 
                Version = "1.0.0.0"
            },
            Capabilities = new ClientCapabilities
            {
                Sampling = new SamplingCapability
                {
                    SamplingHandler = (c, p, t) => Task.FromResult(
                        new CreateMessageResult { 
                            Content = new Content { Text = "result" }, 
                            Model = "test-model", 
                            Role = "test-role", 
                            StopReason = "endTurn" 
                    }),
                },
                Roots = new RootsCapability
                {
                    ListChanged = true,
                    RootsHandler = (t, r) => Task.FromResult(new ListRootsResult { Roots = [] }),
                }
            }
        };

        var clientTransport = (IClientTransport?)Activator.CreateInstance(transportType);
        IMcpClient? client = null;

        var actionTask = McpClientFactory.CreateAsync(serverConfig, clientOptions, (config, logger) => clientTransport ?? new NopTransport(), new Mock<ILoggerFactory>().Object, CancellationToken.None);

        // Act
        if (clientTransport is FailureTransport)
        {
            var exception = await Assert.ThrowsAsync<InvalidOperationException>(async() => await actionTask);
            Assert.Equal(FailureTransport.ExpectedMessage, exception.Message);
        }
        else
        {
            client = await actionTask;

            // Assert
            Assert.NotNull(client);
        }        
    }

    private class NopTransport : ITransport, IClientTransport
    {
        private readonly Channel<IJsonRpcMessage> _channel = Channel.CreateUnbounded<IJsonRpcMessage>();

        public bool IsConnected => true;

        public ChannelReader<IJsonRpcMessage> MessageReader => _channel.Reader;

        public Task<ITransport> ConnectAsync(CancellationToken cancellationToken = default) => Task.FromResult<ITransport>(this);

        public ValueTask DisposeAsync() => default;

        public virtual Task SendMessageAsync(IJsonRpcMessage message, CancellationToken cancellationToken = default)
        {
            switch (message)
            {
                case JsonRpcRequest:
                    _channel.Writer.TryWrite(new JsonRpcResponse
                    {
                        Id = ((JsonRpcRequest)message).Id,
                        Result = JsonSerializer.SerializeToNode(new InitializeResult
                        {
                            Capabilities = new ServerCapabilities(),
                            ProtocolVersion = "2024-11-05",
                            ServerInfo = new Implementation
                            {
                                Name = "NopTransport",
                                Version = "1.0.0"
                            },
                        }),
                    });
                    break;
            }

            return Task.CompletedTask;
        }
    }

    private sealed class FailureTransport : NopTransport 
    {
        public const string ExpectedMessage = "Something failed";

        public override Task SendMessageAsync(IJsonRpcMessage message, CancellationToken cancellationToken = default)
        {
            throw new InvalidOperationException(ExpectedMessage);
        }
    }
}