Fix macOS CI hang: suppress createdump in conformance tests

On macOS, the createdump tool hangs indefinitely due to ptrace/SIP
restrictions when invoked by grandchild .NET processes that inherit
DOTNET_DbgEnableMiniDump=1 from dotnet test --blame-crash.

- Suppress mini-dump generation on macOS only for conformance child
  processes (the runtime still prints crash diagnostics to stderr)
- Add 5-minute process timeout to conformance test runners as a
  safety net against any future hangs

Author: stephentoub

tests/Common/Utils/NodeHelpers.cs

@@ -83,10 +83,11 @@ public static ProcessStartInfo ConformanceTestStartInfo(string arguments)
         var repoRoot = FindRepoRoot();
         var binPath = Path.Combine(repoRoot, "node_modules", ".bin", "conformance");
 
+        ProcessStartInfo startInfo;
         if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
         {
             // On Windows, node_modules/.bin contains .cmd shims that can be executed directly
-            return new ProcessStartInfo
+            startInfo = new ProcessStartInfo
             {
                 FileName = $"{binPath}.cmd",
                 Arguments = arguments,
@@ -98,7 +99,7 @@ public static ProcessStartInfo ConformanceTestStartInfo(string arguments)
         }
         else
         {
-            return new ProcessStartInfo
+            startInfo = new ProcessStartInfo
             {
                 FileName = binPath,
                 Arguments = arguments,
@@ -108,6 +109,21 @@ public static ProcessStartInfo ConformanceTestStartInfo(string arguments)
                 CreateNoWindow = true
             };
         }
+
+        // On macOS, disable .NET mini-dump file generation for child processes. When
+        // dotnet test runs with --blame-crash, it sets DOTNET_DbgEnableMiniDump=1 in the
+        // environment. This is inherited by grandchild .NET processes (e.g. ConformanceClient
+        // launched via node). On macOS, the createdump tool can hang indefinitely due to
+        // ptrace/SIP restrictions, causing the entire test run to hang. Disabling mini-dumps
+        // only suppresses the dump file creation; the runtime still prints crash diagnostics
+        // (stack traces, signal info, etc.) to stderr, which the test captures.
+        if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+        {
+            startInfo.Environment["DOTNET_DbgEnableMiniDump"] = "0";
+            startInfo.Environment["COMPlus_DbgEnableMiniDump"] = "0";
+        }
+
+        return startInfo;
     }
 
     /// <summary>

tests/ModelContextProtocol.AspNetCore.Tests/ClientConformanceTests.cs

@@ -103,7 +103,20 @@ public async Task RunConformanceTest(string scenario)
         process.BeginOutputReadLine();
         process.BeginErrorReadLine();
 
-        await process.WaitForExitAsync();
+        using var cts = new CancellationTokenSource(TimeSpan.FromMinutes(5));
+        try
+        {
+            await process.WaitForExitAsync(cts.Token);
+        }
+        catch (OperationCanceledException)
+        {
+            process.Kill(entireProcessTree: true);
+            return (
+                Success: false,
+                Output: outputBuilder.ToString(),
+                Error: errorBuilder.ToString() + "\nProcess timed out after 5 minutes and was killed."
+            );
+        }
 
         return (
             Success: process.ExitCode == 0,

tests/ModelContextProtocol.AspNetCore.Tests/ServerConformanceTests.cs

@@ -167,7 +167,20 @@ private void StartConformanceServer()
         process.BeginOutputReadLine();
         process.BeginErrorReadLine();
 
-        await process.WaitForExitAsync();
+        using var cts = new CancellationTokenSource(TimeSpan.FromMinutes(5));
+        try
+        {
+            await process.WaitForExitAsync(cts.Token);
+        }
+        catch (OperationCanceledException)
+        {
+            process.Kill(entireProcessTree: true);
+            return (
+                Success: false,
+                Output: outputBuilder.ToString(),
+                Error: errorBuilder.ToString() + "\nProcess timed out after 5 minutes and was killed."
+            );
+        }
 
         return (
             Success: process.ExitCode == 0,