def test_diff_series_too_short(self):
        """
        Tests that `Diff` throws error is length of series is less than `sum(lags)` (i.e.
        there's not enough data to fit the differencer)
        """
        lags = (1000,)
        diff = Diff(lags=lags)
        with pytest.raises(ValueError) as e:
            diff.fit(self.sine_series)
        assert (
            f"Series requires at least {sum(lags) + 1} timesteps "
            f"to difference with lags {lags}; series only "
            f"has {self.sine_series.n_timesteps} timesteps."
        ) == str(e.value)

        Tests that `Diff` throws error is length of series is less than `sum(lags)` (i.e.
        there's not enough data to fit the differencer)
        
darts/tests/dataprocessing/transformers/test_diff.py