'Test XML export with transcripts being overridden to None.'

def test_export_to_xml_with_transcripts_as_none(self):

    self.descriptor.transcripts = None
    xml = self.descriptor.definition_to_xml(None)
    expected = '<video    url_name="SampleProblem"    download_video="false"/>\n'
    self.assertEquals(expected, etree.tostring(xml, pretty_print=True))
