code: def test_recursive_predict_output_when_regressor_is_LinearRegression():
      """
      Test _recursive_predict output when using LinearRegression as regressor.
      """
      forecaster = ForecasterAutoreg(LinearRegression(), lags=3)
      forecaster.fit(y=pd.Series(np.arange(50)))
      predictions = forecaster._recursive_predict(
          steps=5,
          last_window=forecaster.last_window.to_numpy(),
          exog=None,
      )
      expected = np.array([50.0, 51.0, 52.0, 53.0, 54.0])
      assert predictions == approx(expected)
  
imports: from pytest import approx
  import numpy
  import pandas
  from skforecast.ForecasterAutoreg import ForecasterAutoreg
  from sklearn.linear_model import LinearRegression
label_desc: Use image node_id 1 for calling a global function with example usage: test_recursive_predict_output_when_regressor_is_LinearRegression() without return types