def test_feature_times_no_lags_specified_error(self):
        """
        Tests that `_get_feature_times` throws correct error
        when no lags have been specified.
        """
        target = linear_timeseries(start=1, length=20, freq=1)
        with pytest.raises(ValueError) as err:
            _get_feature_times(target_series=target, is_training=False)
        assert (
            "Must specify at least one of: `lags`, `lags_past_covariates`, `lags_future_covariates`."
            == str(err.value)
        )

        Tests that `_get_feature_times` throws correct error
        when no lags have been specified.
        
darts/tests/utils/tabularization/test_get_feature_times.py