check_forecaster_not_fitted_error¶

def check_forecaster_not_fitted_error(forecaster, y: pl.DataFrame, X_actual: pl.DataFrame | None = None) -> None:
    """Check accessing fitted attributes before fit() raises NotFittedError.

    Parameters
    ----------
    forecaster : BaseForecaster
        Unfitted forecaster instance
    y : pl.DataFrame
        Unused; retained for API uniformity with other check functions.
    X_actual : pl.DataFrame, optional
        Unused; retained for API uniformity with other check functions.

    Raises
    ------
    AssertionError
        If NotFittedError is not raised when accessing fitted attributes

    """
    forecaster_clone = clone(forecaster)

    # Should raise NotFittedError when checking if fitted
    try:
        check_is_fitted(forecaster_clone, "fit_forecasting_horizon_")
        raise AssertionError(
            f"{forecaster_clone.__class__.__name__} should raise NotFittedError "
            f"when accessing fit_forecasting_horizon_ before fit()"
        )
    except NotFittedError:
        # Expected behavior
        pass