def METHOD_NAME():
    forecast = QuantileForecast(
        forecast_arrays=np.ones(shape=(1, 12)),
        start_date=pd.Period("2022-03-04 00", freq="H"),
        forecast_keys=["mean"],
    )
    assert forecast.prediction_length == 12
    assert len(forecast.index) == 12
    assert forecast.index[0] == pd.Period("2022-03-04 00", freq="H")
    for level in [0.1, 0.5, 0.7]:
        assert np.isnan(forecast.quantile(level)).all()
    assert np.equal(forecast.mean, 1).all()