def METHOD_NAME(self):
    xml = plugin.get_definition_xml("invoiceClassification", version="1")
    self.assertIsInstance(xml, str)
    self.assertNotEqual(xml, "")
    # check that it can be parsed with lxml
    tree = etree.fromstring(xml.encode("utf-8"))
    default_ns = tree.nsmap[None]
    self.assertEqual(tree.tag, f"{{{default_ns}}}definitions")