GH-93850: Fix test_asyncio exception ignored tracebacks (#93854)

diff --git a/Lib/test/test_asyncio/test_runners.py b/Lib/test/test_asyncio/test_runners.py
index 94d449f4791844d8530ebb8098c21aec3322d7c9..7780a5f15e1b4477fb2e176ff5db3611f186f1da 100644 (file)
--- a/Lib/test/test_asyncio/test_runners.py
+++ b/Lib/test/test_asyncio/test_runners.py
@@ -44,6 +44,9 @@ class BaseTest(unittest.TestCase):
     def new_loop(self):
         loop = asyncio.BaseEventLoop()
         loop._process_events = mock.Mock()
+        # Mock waking event loop from select
+        loop._write_to_self = mock.Mock()
+        loop._write_to_self.return_value = None
         loop._selector = mock.Mock()
         loop._selector.select.return_value = ()
         loop.shutdown_ag_run = False