Add comments

tests/test_qeventloop.py

@@ -554,6 +554,11 @@ def test_regression_bug13(loop, sock_pair):
     client_done, server_done = asyncio.Future(), asyncio.Future()
 
     if os.name == "nt":
+        # On Windows, `loop.add_reader` and `loop.add_writer`
+        # are not supported by Python's `asyncio` due to platform limitations.
+        # Though `qasync` does provide those methods on Windows,
+        # it doesn't guarantee safety against race conditions like on Unix.
+        # https://docs.python.org/3/library/asyncio-platforms.html
         return
 
     async def server_coro():