def METHOD_NAME(self):
    ack = self.message.ack = Mock()
    ack.side_effect = KeyError('foo')
    logger = Mock()
    self.message.ack_log_error(logger, KeyError)
    ack.assert_called_with(multiple=False)
    logger.critical.assert_called()
    assert "Couldn't ack" in logger.critical.call_args[0][0]