def METHOD_NAME(self):
    case_runs = TestCaseRun.objects.filter(pk__in=[self.case_run_1.pk, self.case_run_2.pk])
    exporter = TCR2File(case_runs)
    xml_buff = io.StringIO()
    exporter.write_to_xml(xml_buff)
    xml_doc = xml_buff.getvalue()
    xml_buff.close()
    return xml_doc