bpo-34679: Restore instantiation Windows IOCP event loop from non-main thread (GH-15492)

* Restore running proactor event loop from non-main thread

Co-Authored-By: Kyle Stanley <aeros167@gmail.com>
(cherry picked from commit 1c0600998681295735a18690fae184b0c9a4ca51)

Co-authored-by: Andrew Svetlov <andrew.svetlov@gmail.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/Lib/test/test_asyncio/test_windows_events.py b/Lib/test/test_asyncio/test_windows_events.py
index 6454326..d0ba193 100644
--- a/Lib/test/test_asyncio/test_windows_events.py
+++ b/Lib/test/test_asyncio/test_windows_events.py
@@ -59,6 +59,25 @@ class ProactorLoopCtrlC(test_utils.TestCase):
         thread.join()
 
 
+class ProactorMultithreading(test_utils.TestCase):
+    def test_run_from_nonmain_thread(self):
+        finished = False
+
+        async def coro():
+            await asyncio.sleep(0)
+
+        def func():
+            nonlocal finished
+            loop = asyncio.new_event_loop()
+            loop.run_until_complete(coro())
+            finished = True
+
+        thread = threading.Thread(target=func)
+        thread.start()
+        thread.join()
+        self.assertTrue(finished)
+
+
 class ProactorTests(test_utils.TestCase):
 
     def setUp(self):