code: def test_check_exog_MissingValuesExogWarning_when_exog_has_missing_values_and_allow_nan_False(
      exog,
  ):
      """
      Check MissingValuesExogWarning is issued when y has missing values
      """
      warn_msg = re.escape(
          (
              "`exog` has missing values. Most machine learning models do "
              "not allow missing values. Fitting the forecaster may fail."
          )
      )
      with pytest.warns(MissingValuesExogWarning, match=warn_msg):
          check_exog(exog, allow_nan=False)
  
file_path: skforecast/skforecast/utils/tests/test_check_exog.py
imports: import re
  import pytest
  import numpy
  import pandas
  from skforecast.utils import check_exog
  from skforecast.exceptions import MissingValuesExogWarning
label_desc: Use image node_id 2 for calling a global function with example usage: test_check_exog_MissingValuesExogWarning_when_exog_has_missing_values_and_allow_nan_False(exog) without return types