René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"`IsolatedAsyncioTestCase` does not call `asyncio.set_event_loop` before `setUp` anymore, `asyncio.Runner`+`PidFdChildWatcher` leaves zombie processes","articleBody":"demo reproducer:\r\n\r\n```python\r\nimport unittest\r\nimport asyncio\r\n\r\nclass DemoTestCase1(unittest.IsolatedAsyncioTestCase):\r\n    def setUp(self):\r\n        self.loop = asyncio.get_event_loop_policy().get_event_loop()\r\n\r\n    async def test_demo(self):\r\n        print(\"hello!\")\r\n\r\n\r\nclass DemoTestCase2(unittest.IsolatedAsyncioTestCase):\r\n    def setUp(self):\r\n        self.loop = asyncio.get_event_loop_policy().get_event_loop()\r\n\r\n    async def test_demo(self):\r\n        print(\"hello!\")\r\n\r\nif __name__ == \"__main__\":\r\n    unittest.main()\r\n```\r\n\r\nsee also https://github.com/python/cpython/issues/93896\r\n\r\n\r\n```\r\n graingert@conscientious  testing310  ~/projects  python3.10 foo.py \r\nhello!\r\n.hello!\r\n.\r\n----------------------------------------------------------------------\r\nRan 2 tests in 0.002s\r\n\r\nOK\r\n```\r\n\r\n```\r\n graingert@conscientious  testing310  ~/projects  python3.11 foo.py \r\nhello!\r\n.E\r\n======================================================================\r\nERROR: test_demo (__main__.DemoTestCase2.test_demo)\r\n----------------------------------------------------------------------\r\nTraceback (most recent call last):\r\n  File \"/usr/lib/python3.11/unittest/async_case.py\", line 82, in _callSetUp\r\n    self._asyncioTestContext.run(self.setUp)\r\n  File \"/home/graingert/projects/foo.py\", line 14, in setUp\r\n    self.loop = asyncio.get_event_loop_policy().get_event_loop()\r\n                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\r\n  File \"/usr/lib/python3.11/asyncio/events.py\", line 677, in get_event_loop\r\n    raise RuntimeError('There is no current event loop in thread %r.'\r\nRuntimeError: There is no current event loop in thread 'MainThread'.\r\n\r\n----------------------------------------------------------------------\r\nRan 2 tests in 0.002s\r\n\r\nFAILED (errors=1)\r\n```\r\n\r\nit looks like this is because `asyncio.Runner` calls `asyncio.set_event_loop(` in `Runner.run`","author":{"url":"https://github.com/graingert","@type":"Person","name":"graingert"},"datePublished":"2022-08-06T08:50:06.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":23},"url":"https://github.com/95736/cpython/issues/95736"}