def test_monitor_multiple_start():
    """
    Calling ``Monitor.start`` multiple times has no effects beyond those of
    calling it once.
    """
    monitor = Monitor(MagicMock())
    monitor.timer = MagicMock()
    monitor.start()
    monitor.start()
    assert monitor.timer.mock_calls == [call.start(2, now=True)]
def test_monitor_start():
    monitor = Monitor(MagicMock())
    monitor.timer = MagicMock()
    monitor.start()
    assert monitor.timer.mock_calls == [call.start(2, now=True)]