PYTHON-4537 - Use selector asyncio loop on windows tests

Author: NoahStapp

test/__init__.py

@@ -79,6 +79,12 @@
 
 _IS_SYNC = True
 
+# The default asyncio loop implementation on Windows
+# has issues with sharing sockets across loops (https://github.com/python/cpython/issues/122240)
+# We explicitly use a different loop implementation here to prevent that issue
+if not _IS_SYNC and sys.platform == "win32":
+    asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())
+
 
 class ClientContext:
     client: MongoClient

test/asynchronous/__init__.py

@@ -79,6 +79,12 @@
 
 _IS_SYNC = False
 
+# The default asyncio loop implementation on Windows
+# has issues with sharing sockets across loops (https://github.com/python/cpython/issues/122240)
+# We explicitly use a different loop implementation here to prevent that issue
+if not _IS_SYNC and sys.platform == "win32":
+    asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())
+
 
 class AsyncClientContext:
     client: AsyncMongoClient