"""Test for issue #552: stdio_client hangs on Windows."""

import sys

from textwrap import dedent

import anyio

import pytest

from mcp import ClientSession, StdioServerParameters

from mcp.client.stdio import stdio_client

@pytest.mark.skipif(sys.platform != "win32", reason="Windows-specific test") # pragma: no cover

@pytest.mark.anyio

async def test_windows_stdio_client_with_session():

"""Test the exact scenario from issue #552: Using ClientSession with stdio_client.

This reproduces the original bug report where stdio_client hangs on Windows 11

when used with ClientSession.

"""

# Create a minimal MCP server that responds to initialization

server_script = dedent("""

import json

import sys

# Read initialization request

line = sys.stdin.readline()

# Send initialization response

response = {

"jsonrpc": "2.0",

"id": 1,

"result": {

"protocolVersion": "1.0",

"capabilities": {},

"serverInfo": {"name": "test-server", "version": "1.0"}

}

}

print(json.dumps(response))

sys.stdout.flush()

# Exit after a short delay

import time

time.sleep(0.1)

sys.exit(0)

""").strip()

params = StdioServerParameters(

command=sys.executable,

args=["-c", server_script],

)

# This is the exact pattern from the bug report

with anyio.fail_after(10):

try:

async with stdio_client(params) as (read, write):

async with ClientSession(read, write) as session:

await session.initialize()

# Should exit ClientSession without hanging

# Should exit stdio_client without hanging

except Exception:

# Connection errors are expected when process exits

pass