human
I wrote the below code

    called = []
    def assert_correct_xml(filename, content):
        called.append(True)
        assert_xsd_valid(filename, content)
        root = etree.fromstring(content)
        assert_equals(root.get('tests'), '2')
        assert_equals(root.get('failures'), '1')
        assert_equals(len(root.getchildren()), 2)
        (passed, failed) = root.findall('testcase')
        assert_equals(passed.get('name'), 'Given    my    step    that    passes')
        assert_true((float(passed.get('time')) > 0))
        assert_equals(failed.get('name'), 'Given    my    step    that    blows    a    exception')
        assert_true((float(failed.get('time')) > 0))
        assert_true((failed.find('failure') is not None))
    old = xunit_output.wrt_output
    xunit_output.wrt_output = assert_correct_xml
    runner = Runner(feature_name('error_traceback'), enable_xunit=True)
    runner.run()
    assert_equals(1, len(called), 'Function    not    called')
    xunit_output.wrt_output = old

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

@with_setup(prepare_stdout, registry.clear)
def test_xunit_output_with_one_error():