I am trying to run an async test case in a loop, with Python’s unittesting framework; however, I am running into a brick wall with the error: AssertionError: asyncio runner is already initialized

As part of my loop, I have to reinitialise the test suite as following:

tests = get_tests()
suite = unittest.TestSuite(tests)
runner = unittest.TextTestRunner()

for _ in range(3):
  result = runner.run(suite)
  unittest.registerResult(result)
  suite = unittest.TestSuite(tests)

The test that is causing problems is (minimal version):

async def basic_async_func():
    await asyncio.sleep(2)
    return 'hello'

class MyAsyncTestClass(unittest.IsolatedAsyncioTestCase):

    @classmethod
    def setUpClass(cls):
        cls.name = 'foo'
        # Handling async class set up
        asyncio.run(cls.asyncSetUpClass())

    @classmethod
    async def asyncSetUpClass(cls):
        cls.statement = await basic_async_func()

    def test_set_up(self):
        self.assertEqual(self.statement,'hello')

I get the following output:

Traceback (most recent call last):
  File "/home/main.py", line 151, in <module>
    main()
  File "/home/main.py", line 116, in main
    test_result = runner.run(single_suite)
                  ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/unittest/runner.py", line 240, in run
    test(result)
  File "/usr/lib/python3.12/unittest/suite.py", line 84, in __call__
    return self.run(*args, **kwds)
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/unittest/suite.py", line 122, in run
    test(result)
  File "/usr/lib/python3.12/unittest/case.py", line 690, in __call__
    return self.run(*args, **kwds)
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/unittest/async_case.py", line 129, in run
    self._setupAsyncioRunner()
  File "/usr/lib/python3.12/unittest/async_case.py", line 120, in _setupAsyncioRunner
    assert self._asyncioRunner is None, 'asyncio runner is already initialized'
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: asyncio runner is already initialized

I have tried a few different things to resolve this.

Firstly, I’d originally manually set an event loop:

cls.loop = asyncio.new_event_loop()
asyncio.set_event_loop(cls.loop)
cls.loop.run_until_complete(cls.asyncSetUpClass())

Secondly, I tried using the asyncio.runner context manager:

with asyncio.Runner() as runner:
  runner.run(cls.asyncSetUpClass())

Lastly, I tried to remove the classSetUp method (though this has been a requirement of my actual, non-minimal test case), and to instead just use IsolatedAsyncioTestCase’s asyncSetUp function:

async def asyncSetUp(self):
  self.name = 'foo'
  self.statement = await basic_async_func()

All of these have given the same error output as above. I am wondering if I need to somehow set or close an asyncio runner at the level of the loop in the first code block? (I tried re-initialising the unittest runner in every loop iteration and this didn’t work)