gh-130736: Fix asyncio test_shutdown_default_executor_timeout() (#130800)

Replace time.sleep() with threading.Event.

Author: vstinner

Lib/test/test_asyncio/test_base_events.py

@@ -233,20 +233,25 @@ def test_set_default_executor_error(self):
         self.assertIsNone(self.loop._default_executor)
 
     def test_shutdown_default_executor_timeout(self):
+        event = threading.Event()
+
         class DummyExecutor(concurrent.futures.ThreadPoolExecutor):
             def shutdown(self, wait=True, *, cancel_futures=False):
                 if wait:
-                    time.sleep(0.1)
+                    event.wait()
 
         self.loop._process_events = mock.Mock()
         self.loop._write_to_self = mock.Mock()
         executor = DummyExecutor()
         self.loop.set_default_executor(executor)
 
-        with self.assertWarnsRegex(RuntimeWarning,
-                                   "The executor did not finishing joining"):
-            self.loop.run_until_complete(
-                self.loop.shutdown_default_executor(timeout=0.01))
+        try:
+            with self.assertWarnsRegex(RuntimeWarning,
+                                       "The executor did not finishing joining"):
+                self.loop.run_until_complete(
+                    self.loop.shutdown_default_executor(timeout=0.01))
+        finally:
+            event.set()
 
     def test_call_soon(self):
         def cb():