code: def test_output_preprocess_exog_when_exog_index_is_not_DatetimeIndex_or_RangeIndex():
      """
      Test values returned by when exog is a pandas Series without DatetimeIndex or RangeIndex.
      """
      exog = pd.Series(data=np.arange(3), index=["0", "1", "2"])
      results = preprocess_exog(exog)
      expected = (np.arange(3), pd.RangeIndex(start=0, stop=3, step=1))
  
      assert (results[0] == expected[0]).all()
      assert (results[1] == expected[1]).all()
  
file_path: skforecast/skforecast/utils/tests/test_preproces_exog.py
imports: import pytest
  import numpy
  import pandas
  from skforecast.utils import preprocess_exog
label_desc: Use image node_id 4 for calling a global function with example usage: test_output_preprocess_exog_when_exog_index_is_not_DatetimeIndex_or_RangeIndex() without return types