Fix StdioServerTransport.DisposeAsync hang (#235)

- It's not just Unix, it's all platforms that can hang - Windows doesn't hang on Ctrl-C because that triggers the end of the Stream, but that doesn't help in IHostApplicationLifetime.StopAsync() scenarios 4e9627e311/src/libraries/System.Console/src/System/ConsolePal.Unix.ConsoleStream.cs (L13) 4e9627e311/src/libraries/System.Console/src/System/ConsolePal.Windows.cs (L1149)
2025-04-08 10:20:16 -07:00 · 2025-04-08 10:20:16 -07:00 · bab74d5895
commit bab74d5895
parent 3e21f3594a
1 changed files with 114 additions and 8 deletions
--- a/tests/ModelContextProtocol.Tests/StdioServerIntegrationTests.cs
+++ b/tests/ModelContextProtocol.Tests/StdioServerIntegrationTests.cs
@ -0,0 +1,66 @@
+using ModelContextProtocol.Client;
+using ModelContextProtocol.Protocol.Transport;
+using ModelContextProtocol.Tests.Utils;
+using System.Diagnostics;
+using System.Runtime.InteropServices;
+
+namespace ModelContextProtocol.Tests;
+
+public class StdioServerIntegrationTests(ITestOutputHelper testOutputHelper) : LoggedTest(testOutputHelper)
+{
+    public static bool CanSendSigInt { get; } = RuntimeInformation.IsOSPlatform(OSPlatform.Linux) || RuntimeInformation.IsOSPlatform(OSPlatform.OSX);
+    private const int SIGINT = 2;
+
+    [Fact(Skip = "Platform not supported by this test.", SkipUnless = nameof(CanSendSigInt))]
+    public async Task SigInt_DisposesTestServerWithHosting_Gracefully()
+    {
+        using var process = new Process
+        {
+            StartInfo = new ProcessStartInfo
+            {
+                FileName = "dotnet",
+                Arguments = "TestServerWithHosting.dll",
+                RedirectStandardInput = true,
+                RedirectStandardOutput = true,
+                UseShellExecute = false,
+                CreateNoWindow = true,
+            }
+        };
+
+        process.Start();
+
+        await using var streamServerTransport = new StreamServerTransport(
+            process.StandardOutput.BaseStream,
+            process.StandardInput.BaseStream,
+            serverName: "TestServerWithHosting");
+
+        await using var client = await McpClientFactory.CreateAsync(
+            new TestClientTransport(streamServerTransport),
+            loggerFactory: LoggerFactory,
+            cancellationToken: TestContext.Current.CancellationToken);
+
+        // I considered writing a similar test for Windows using Ctrl-C, then saw that dotnet watch doesn't even send a Ctrl-C
+        // signal because it's such a pain without support for CREATE_NEW_PROCESS_GROUP in System.Diagnostics.Process.
+        // https://github.com/dotnet/sdk/blob/43b1c12e3362098a23ca1018503eb56516840b6a/src/BuiltInTools/dotnet-watch/Internal/ProcessRunner.cs#L277-L303
+        // https://github.com/dotnet/runtime/issues/109432, https://github.com/dotnet/runtime/issues/44944
+        Assert.Equal(0, kill(process.Id, SIGINT));
+
+        using var shutdownCts = CancellationTokenSource.CreateLinkedTokenSource(TestContext.Current.CancellationToken);
+        shutdownCts.CancelAfter(TimeSpan.FromSeconds(10));
+        await process.WaitForExitAsync(shutdownCts.Token);
+
+        Assert.True(process.HasExited);
+        Assert.Equal(0, process.ExitCode);
+    }
+
+    [DllImport("libc", SetLastError = true)]
+    private static extern int kill(int pid, int sig);
+
+    private sealed class TestClientTransport(ITransport sessionTransport) : IClientTransport
+    {
+        public string Name => nameof(TestClientTransport);
+
+        public Task<ITransport> ConnectAsync(CancellationToken cancellationToken = default)
+            => Task.FromResult(sessionTransport);
+    }
+}