def test_plain_unittest_does_not_support_async(pytester: Pytester) -> None:
    """Async functions in plain unittest.TestCase subclasses are not supported without plugins.

    This test exists here to avoid introducing this support by accident, leading users
    to expect that it works, rather than doing so intentionally as a feature.

    See https://github.com/pytest-dev/pytest-asyncio/issues/180 for more context.
    """
    pytester.copy_example("unittest/test_unittest_plain_async.py")
    result = pytester.runpytest_subprocess()
    if hasattr(sys, "pypy_version_info"):
        # in PyPy we can't reliable get the warning about the coroutine not being awaited,
        # because it depends on the coroutine being garbage collected; given that
        # we are running in a subprocess, that's difficult to enforce
        expected_lines = ["*1 passed*"]
    else:
        expected_lines = [
            "*RuntimeWarning: coroutine * was never awaited",
            "*1 passed*",
        ]
    result.stdout.fnmatch_lines(expected_lines)
Async functions in plain unittest.TestCase subclasses are not supported without plugins.

    This test exists here to avoid introducing this support by accident, leading users
    to expect that it works, rather than doing so intentionally as a feature.

    See https://github.com/pytest-dev/pytest-asyncio/issues/180 for more context.
    
testing/test_unittest.py