'Mock query to the backend collects stats on all physical devices.'

def test_update_volume_stats(self):

    backend_name = self.conf.volume_backend_name
    self.driver.common._get_volume_stats = mock.Mock(return_value=GET_VOLUME_STATS_RESPONSE)
    result = self.driver._update_volume_stats()
    self.driver.common._get_volume_stats.assert_called_with(self.conf.san_ip)
    self.assertEqual(backend_name, self.driver.stats['volume_backend_name'])
    self.assertEqual('iSCSI', self.driver.stats['storage_protocol'])
    self.assertIsNone(result)
