human
I wrote the below code

    py_file = testdir.makepyfile('\n                                import    pytest\n                                @pytest.mark.parametrize("arg",    [None,    1.3,    "2-3"])\n                                def    test_func(arg):\n                                                pass\n                ')
    file_name = os.path.basename(py_file.strpath)
    rec = testdir.inline_run(((file_name + '::') + 'test_func'))
    rec.assertoutcome(passed=3)

What's a good function header?
assistant
#Here's a good function header.

def test_parametrized_collected_from_command_line(testdir):