From 64b67614403d429920b42d83f0b075c80aa530f3 Mon Sep 17 00:00:00 2001
From: Kumar Aditya <59607654+kumaraditya303@users.noreply.github.com>
Date: Tue, 16 Aug 2022 21:22:06 +0530
Subject: [PATCH] GH-95736: fix IsolatedAsyncioTestCase to initialize Runner
 before calling setup functions  (GH-95898) (cherry picked from commit
 9d515997f943b7b510268448f372dabcbf957858)

Co-authored-by: Kumar Aditya <59607654+kumaraditya303@users.noreply.github.com>
---
 Lib/unittest/async_case.py                        |  4 ++++
 Lib/unittest/test/test_async_case.py              | 15 +++++++++++++++
 .../2022-08-11-18-22-29.gh-issue-95736.LzRZXe.rst |  1 +
 3 files changed, 20 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2022-08-11-18-22-29.gh-issue-95736.LzRZXe.rst

diff --git a/Lib/unittest/async_case.py b/Lib/unittest/async_case.py
index a90eed98f87140..8b06fad0620946 100644
--- a/Lib/unittest/async_case.py
+++ b/Lib/unittest/async_case.py
@@ -116,6 +116,10 @@ def _setupAsyncioRunner(self):
         assert self._asyncioRunner is None, 'asyncio runner is already initialized'
         runner = asyncio.Runner(debug=True)
         self._asyncioRunner = runner
+        # Force loop to be initialized and set as the current loop
+        # so that setUp functions can use get_event_loop() and get the
+        # correct loop instance.
+        runner.get_loop()
 
     def _tearDownAsyncioRunner(self):
         runner = self._asyncioRunner
diff --git a/Lib/unittest/test/test_async_case.py b/Lib/unittest/test/test_async_case.py
index beadcac070b434..f59fc760d3812f 100644
--- a/Lib/unittest/test/test_async_case.py
+++ b/Lib/unittest/test/test_async_case.py
@@ -434,6 +434,21 @@ async def cleanup(self, fut):
         test.doCleanups()
         self.assertEqual(events, ['asyncSetUp', 'test', 'cleanup'])
 
+    def test_setup_get_event_loop(self):
+        # See https://github.com/python/cpython/issues/95736
+        # Make sure the default event loop is not used
+        asyncio.set_event_loop(None)
+
+        class TestCase1(unittest.IsolatedAsyncioTestCase):
+            def setUp(self):
+                asyncio.get_event_loop_policy().get_event_loop()
+
+            async def test_demo1(self):
+                pass
+
+        test = TestCase1('test_demo1')
+        result = test.run()
+        self.assertTrue(result.wasSuccessful())
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/Misc/NEWS.d/next/Library/2022-08-11-18-22-29.gh-issue-95736.LzRZXe.rst b/Misc/NEWS.d/next/Library/2022-08-11-18-22-29.gh-issue-95736.LzRZXe.rst
new file mode 100644
index 00000000000000..abc270fe35ca65
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-08-11-18-22-29.gh-issue-95736.LzRZXe.rst
@@ -0,0 +1 @@
+Fix :class:`unittest.IsolatedAsyncioTestCase` to set event loop before calling setup functions. Patch by Kumar Aditya.