def METHOD_NAME(self) -> None:
    response = self.get_json(
        '%s/staging/%s?selected_subtopic_ids=1,2' % (
            feconf.PRACTICE_SESSION_DATA_URL_PREFIX,
            'invalid'),
        expected_status_int=400)
    error_msg = (
        'Schema validation for \'selected_subtopic_ids\' failed: '
        'Extra data: line 1 column 2 (char 1)'
    )
    self.assertEqual(response['error'], error_msg)