csharp-sdk/tests/ModelContextProtocol.Tests/Server/McpServerToolTests.cs

using Microsoft.Extensions.AI;
using Microsoft.Extensions.DependencyInjection;
using ModelContextProtocol.Protocol.Types;
using ModelContextProtocol.Server;
using Moq;
using System.Reflection;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace ModelContextProtocol.Tests.Server;

public class McpServerToolTests
{
    [Fact]
    public void Create_InvalidArgs_Throws()
    {
        Assert.Throws<ArgumentNullException>("function", () => McpServerTool.Create(null!));
        Assert.Throws<ArgumentNullException>("method", () => McpServerTool.Create((MethodInfo)null!));
        Assert.Throws<ArgumentNullException>("method", () => McpServerTool.Create((Delegate)null!));
    }

    [Fact]
    public async Task SupportsIMcpServer()
    {
        Mock<IMcpServer> mockServer = new();

        McpServerTool tool = McpServerTool.Create((IMcpServer server) =>
        {
            Assert.Same(mockServer.Object, server);
            return "42";
        });

        Assert.DoesNotContain("server", JsonSerializer.Serialize(tool.ProtocolTool.InputSchema));

        var result = await tool.InvokeAsync(
            new RequestContext<CallToolRequestParams>(mockServer.Object, null),
            TestContext.Current.CancellationToken);
        Assert.Equal("42", result.Content[0].Text);
    }

    [Fact]
    public async Task SupportsServiceFromDI()
    {
        MyService expectedMyService = new();

        ServiceCollection sc = new();
        sc.AddSingleton(expectedMyService);
        IServiceProvider services = sc.BuildServiceProvider();

        McpServerTool tool = McpServerTool.Create((MyService actualMyService) =>
        {
            Assert.Same(expectedMyService, actualMyService);
            return "42";
        }, services: services);

        Assert.DoesNotContain("actualMyService", JsonSerializer.Serialize(tool.ProtocolTool.InputSchema));

        Mock<IMcpServer> mockServer = new();

        var result = await tool.InvokeAsync(
            new RequestContext<CallToolRequestParams>(mockServer.Object, null),
            TestContext.Current.CancellationToken);
        Assert.True(result.IsError);

        mockServer.SetupGet(x => x.Services).Returns(services);

        result = await tool.InvokeAsync(
            new RequestContext<CallToolRequestParams>(mockServer.Object, null),
            TestContext.Current.CancellationToken);
        Assert.Equal("42", result.Content[0].Text);
    }

    [Fact]
    public async Task SupportsOptionalServiceFromDI()
    {
        MyService expectedMyService = new();

        ServiceCollection sc = new();
        sc.AddSingleton(expectedMyService);
        IServiceProvider services = sc.BuildServiceProvider();

        McpServerTool tool = McpServerTool.Create((MyService? actualMyService = null) =>
        {
            Assert.Null(actualMyService);
            return "42";
        }, services: services);

        var result = await tool.InvokeAsync(
            new RequestContext<CallToolRequestParams>(null!, null),
            TestContext.Current.CancellationToken);
        Assert.Equal("42", result.Content[0].Text);
    }

    [Fact]
    public async Task SupportsDisposingInstantiatedDisposableTargets()
    {
        McpServerTool tool1 = McpServerTool.Create(
            typeof(DisposableToolType).GetMethod(nameof(DisposableToolType.InstanceMethod))!,
            typeof(DisposableToolType));

        var result = await tool1.InvokeAsync(
            new RequestContext<CallToolRequestParams>(null!, null),
            TestContext.Current.CancellationToken);
        Assert.Equal("""{"disposals":1}""", result.Content[0].Text);
    }

    [Fact]
    public async Task SupportsAsyncDisposingInstantiatedAsyncDisposableTargets()
    {
        McpServerTool tool1 = McpServerTool.Create(
            typeof(AsyncDisposableToolType).GetMethod(nameof(AsyncDisposableToolType.InstanceMethod))!,
            typeof(AsyncDisposableToolType));

        var result = await tool1.InvokeAsync(
            new RequestContext<CallToolRequestParams>(null!, null),
            TestContext.Current.CancellationToken);
        Assert.Equal("""{"asyncDisposals":1}""", result.Content[0].Text);
    }

    [Fact]
    public async Task SupportsAsyncDisposingInstantiatedAsyncDisposableAndDisposableTargets()
    {
        McpServerTool tool1 = McpServerTool.Create(
            typeof(AsyncDisposableAndDisposableToolType).GetMethod(nameof(AsyncDisposableAndDisposableToolType.InstanceMethod))!,
            typeof(AsyncDisposableAndDisposableToolType));

        var result = await tool1.InvokeAsync(
            new RequestContext<CallToolRequestParams>(null!, null),
            TestContext.Current.CancellationToken);
        Assert.Equal("""{"asyncDisposals":1,"disposals":0}""", result.Content[0].Text);
    }

    private sealed class MyService;

    private class DisposableToolType : IDisposable
    {
        public int Disposals { get; private set; }

        public void Dispose()
        {
            Disposals++;
        }

        public object InstanceMethod()
        {
            if (Disposals != 0)
            {
                throw new InvalidOperationException("Dispose was called");
            }

            return this;
        }
    }

    private class AsyncDisposableToolType : IAsyncDisposable
    {
        public int AsyncDisposals { get; private set; }

        public ValueTask DisposeAsync()
        {
            AsyncDisposals++;
            return default;
        }

        public object InstanceMethod()
        {
            if (AsyncDisposals != 0)
            {
                throw new InvalidOperationException("DisposeAsync was called");
            }

            return this;
        }
    }

    private class AsyncDisposableAndDisposableToolType : IAsyncDisposable, IDisposable
    {
        [JsonPropertyOrder(0)]
        public int AsyncDisposals { get; private set; }

        [JsonPropertyOrder(1)]
        public int Disposals { get; private set; }

        public void Dispose()
        {
            Disposals++;
        }

        public ValueTask DisposeAsync()
        {
            AsyncDisposals++;
            return default;
        }

        public object InstanceMethod()
        {
            if (Disposals != 0)
            {
                throw new InvalidOperationException("Dispose was called");
            }

            if (AsyncDisposals != 0)
            {
                throw new InvalidOperationException("DisposeAsync was called");
            }

            return this;
        }
    }
}