def test_set_frequency_invalid_rfm(self):
        mock = MagicMock()

        l = LaCrosse('/dev/ttyTEST', 115200)
        l._serial.write = mock

        l.set_frequency(500, rfm=3)
        l._serial.write.assert_called_with(b'400f')
    def test_set_frequency(self):
        mock = MagicMock()

        l = LaCrosse('/dev/ttyTEST', 115200)
        l._serial.write = mock

        l.set_frequency(100)
        l._serial.write.assert_called_with(b'100f')

        l.set_frequency('200')
        l._serial.write.assert_called_with(b'200f')

        l.set_frequency(300, rfm=1)
        l._serial.write.assert_called_with(b'300f')

        l.set_frequency(400, rfm=2)
        l._serial.write.assert_called_with(b'400F')