bpo-28369: Enhance transport socket check in add_reader/writer (#4365)

1 files changed, 7 insertions, 0 deletions

diff --git a/Lib/asyncio/test_utils.py b/Lib/asyncio/test_utils.py
index 65805947fd..c9b19825f2 100644
--- a/Lib/asyncio/test_utils.py
+++ b/Lib/asyncio/test_utils.py
@@ -361,6 +361,13 @@ class TestLoop(base_events.BaseEventLoop):
             handle._args, args)
 
     def _ensure_fd_no_transport(self, fd):
+        if not isinstance(fd, int):
+            try:
+                fd = int(fd.fileno())
+            except (AttributeError, TypeError, ValueError):
+                # This code matches selectors._fileobj_to_fd function.
+                raise ValueError("Invalid file object: "
+                                 "{!r}".format(fd)) from None
         try:
             transport = self._transports[fd]
         except KeyError: