code: def test_statsforecast_mstl(mock_autoets):
      """
      Check that StatsForecast MSTL adapter calls trend forecaster with
      the correct arguments.
      """
      from sktime.datasets import load_airline
  
      y = load_airline()
  
      predict = mock_autoets.return_value.predict
      predict.return_value = {
          "mean": np.arange(36, dtype=np.float64),
          "lo-95.0": np.arange(36, dtype=np.float64),
          "hi-95.0": np.arange(36, dtype=np.float64),
      }
  
      model = StatsForecastMSTL(season_length=[12])
      model.fit(y)
      fh_index = pd.PeriodIndex(
          pd.date_range("1961-01", periods=36, freq="M")
      )
      fh = ForecastingHorizon(fh_index, is_relative=False)
      model.predict_interval(fh, coverage=0.95)
      predict.assert_called_with(36, X=None, level=[95.0])
  
imports: from unittest.mock import patch
  import numpy
  import pandas
  import pytest
  from sktime.forecasting.base import ForecastingHorizon
  from sktime.forecasting.statsforecast import StatsForecastMSTL
  from sktime.tests.test_switch import run_test_for_class
label_desc: Use image node_id 1 for calling a global function with example usage: test_statsforecast_mstl(mock_autoets) without return types