def METHOD_NAME(self):
    with session.begin():
        lc = data_setup.create_labcontroller()
        another_lc = data_setup.create_labcontroller()
    data_setup.unique_name(u'lab%s.testdata.invalid')
    try:
        run_client(['bkr', 'labcontroller-modify',
                    '--fqdn', another_lc.fqdn,
                    lc.fqdn])
        self.fail('Must error out')
    except ClientError as e:
        self.assertIn('FQDN %s already in use' % another_lc.fqdn,
                      e.stderr_output)