From 08d092be5759214b989a84092e2721cfc4382e2e Mon Sep 17 00:00:00 2001
From: Jeremiah Lowin <153965+jlowin@users.noreply.github.com>
Date: Sun, 14 Dec 2025 08:39:44 -0500
Subject: [PATCH] Use WindowsSelectorEventLoopPolicy to fix Windows test
 warnings (#2607)

* fix: skip TextIO log file test on Windows

Avoids PytestUnraisableExceptionWarning caused by ProactorEventLoop
cleanup timing issues with subprocess pipe transports.

* Use WindowsSelectorEventLoopPolicy to fix Windows test warnings

Re-add the SelectorEventLoop fix from bcd2e594 that was inadvertently
removed in cf101c2a. This fixes ProactorEventLoop cleanup warnings
on Windows CI without needing to skip individual tests.
---
 tests/conftest.py | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tests/conftest.py b/tests/conftest.py
index 22487f97e..b45824a9e 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -1,4 +1,6 @@
+import asyncio
 import socket
+import sys
 from collections.abc import Callable
 from pathlib import Path
 from typing import Any
@@ -7,6 +9,11 @@ import pytest
 
 from fastmcp.utilities.tests import temporary_settings
 
+# Use SelectorEventLoop on Windows to avoid ProactorEventLoop crashes
+# See: https://github.com/python/cpython/issues/116773
+if sys.platform == "win32":
+    asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())
+
 
 def pytest_collection_modifyitems(items):
     """Automatically mark tests in integration_tests folder with 'integration' marker."""