#552

tests/issues/test_552_windows_hang.py

@@ -0,0 +1,47 @@
+import asyncio
+import sys
+
+import pytest
+
+from mcp import ClientSession, StdioServerParameters
+from mcp.client.stdio import stdio_client
+
+
+@pytest.mark.skipif(sys.platform != "win32", reason="Windows-specific test")
+@pytest.mark.skipif(sys.version_info < (3, 11), reason="asyncio.timeout in 3.11+")
+@pytest.mark.anyio
+async def test_windows_process_creation():
+    """
+    Test that directly tests the process creation function that was fixed in issue #552.
+    This simpler test verifies that Windows process creation works without hanging.
+    """
+    # Use a simple command that should complete quickly on Windows
+    params = StdioServerParameters(
+        command="cmd",
+        # Echo a valid JSON-RPC response message that will be parsed correctly
+        args=[
+            "/c",
+            "echo",
+            '{"jsonrpc":"2.0","id":1,"result":{"status":"success"}}',
+        ],
+    )
+
+    # Directly test the fixed function that was causing the hanging issue
+    try:
+        # Set a timeout to prevent hanging
+        async with asyncio.timeout(5):
+            # Test the actual process creation function that was fixed
+            async with stdio_client(params) as (read, write):
+                print("inside client")
+                async with ClientSession(read, write) as c:
+                    print("inside ClientSession")
+                    await c.initialize()
+
+    except asyncio.TimeoutError:
+        pytest.xfail("Process creation timed out, indicating a hang issue")
+    except ProcessLookupError:
+        pytest.xfail("Process creation failed with ProcessLookupError")
+    except Exception as e:
+        assert "ExceptionGroup" in repr(e), f"Unexpected error: {e}"
+        assert "ProcessLookupError" in repr(e), f"Unexpected error: {e}"
+        pytest.xfail(f"Expected error: {e}")