'Config: clear_extra_torznabs'

def test_clear_extra_torznabs(self):

    path = '/tmp/notexist'
    random_value = (-1292721)
    self.config_mock['Torznab'] = {'extra_torznabs': [1, 2, 3]}
    self.config_mock['Torznab'] = {'do_not_touch': random_value}
    c = headphones.config.Config(path)
    res = c.clear_extra_torznabs()
    self.assertIsNone(res)
    self.assertEqual(self.config_mock['Torznab']['extra_torznabs'], [])
    self.assertEqual(self.config_mock['Torznab']['do_not_touch'], random_value)
