[Python-checkins] GH-93896: AAlways set event loop in asyncio.run and IsolatedAsyncioTestCase (#94593)

[pablogsal]

https://github.com/python/cpython/commit/14fea6b4d25658bc00adbb97dd40ea3d3e6843ad
commit: 14fea6b4d25658bc00adbb97dd40ea3d3e6843ad
branch: main
author: Kumar Aditya <59607654+kumaraditya303 at users.noreply.github.com>
committer: pablogsal <Pablogsal at gmail.com>
date: 2022-07-06T16:18:21+01:00
summary:

GH-93896: AAlways set event loop in asyncio.run and IsolatedAsyncioTestCase (#94593)

files:
A Misc/NEWS.d/next/Library/2022-07-06-06-02-02.gh-issue-93896.vIgWGr.rst
M Lib/asyncio/runners.py
M Lib/test/test_asyncio/test_runners.py

diff --git a/Lib/asyncio/runners.py b/Lib/asyncio/runners.py
index f524c3b8e424f..7489a50f8e48d 100644
--- a/Lib/asyncio/runners.py
+++ b/Lib/asyncio/runners.py
@@ -52,6 +52,7 @@ def __init__(self, *, debug=None, loop_factory=None):
         self._loop = None
         self._context = None
         self._interrupt_count = 0
+        self._set_event_loop = False
 
     def __enter__(self):
         self._lazy_init()
@@ -70,6 +71,8 @@ def close(self):
             loop.run_until_complete(loop.shutdown_asyncgens())
             loop.run_until_complete(loop.shutdown_default_executor())
         finally:
+            if self._set_event_loop:
+                events.set_event_loop(None)
             loop.close()
             self._loop = None
             self._state = _State.CLOSED
@@ -111,6 +114,8 @@ def run(self, coro, *, context=None):
 
         self._interrupt_count = 0
         try:
+            if self._set_event_loop:
+                events.set_event_loop(self._loop)
             return self._loop.run_until_complete(task)
         except exceptions.CancelledError:
             if self._interrupt_count > 0 and task.uncancel() == 0:
@@ -130,6 +135,7 @@ def _lazy_init(self):
             return
         if self._loop_factory is None:
             self._loop = events.new_event_loop()
+            self._set_event_loop = True
         else:
             self._loop = self._loop_factory()
         if self._debug is not None:
diff --git a/Lib/test/test_asyncio/test_runners.py b/Lib/test/test_asyncio/test_runners.py
index 7780a5f15e1b4..1f6a4983690cd 100644
--- a/Lib/test/test_asyncio/test_runners.py
+++ b/Lib/test/test_asyncio/test_runners.py
@@ -198,6 +198,18 @@ async def main():
         self.assertIsNone(spinner.ag_frame)
         self.assertFalse(spinner.ag_running)
 
+    def test_asyncio_run_set_event_loop(self):
+        #See https://github.com/python/cpython/issues/93896
+
+        async def main():
+            await asyncio.sleep(0)
+            return 42
+
+        policy = asyncio.get_event_loop_policy()
+        policy.set_event_loop = mock.Mock()
+        asyncio.run(main())
+        self.assertTrue(policy.set_event_loop.called)
+
 
 class RunnerTests(BaseTest):
 
diff --git a/Misc/NEWS.d/next/Library/2022-07-06-06-02-02.gh-issue-93896.vIgWGr.rst b/Misc/NEWS.d/next/Library/2022-07-06-06-02-02.gh-issue-93896.vIgWGr.rst
new file mode 100644
index 0000000000000..2283e14de9a9a
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-07-06-06-02-02.gh-issue-93896.vIgWGr.rst
@@ -0,0 +1 @@
+Fix :func:`asyncio.run` and :class:`unittest.IsolatedAsyncioTestCase` to always the set event loop as it was done in Python 3.10 and earlier. Patch by Kumar Aditya.