code: def test_fit_TypeError_offset_DateOffset_y_index_not_DatetimeIndex(y):
      """
      Test TypeError is raised when offset is a DateOffset and y index is
      not a DatetimeIndex or has no freq.
      """
      forecaster = ForecasterEquivalentDate(
          offset=DateOffset(days=1), n_offsets=2, agg_func=np.mean
      )
  
      if isinstance(y.index, pd.DatetimeIndex):
          y.index.freq = None
  
      err_msg = re.escape(
          (
              "If `offset` is a pandas DateOffset, the index of `y` must be a "
              "pandas DatetimeIndex with frequency."
          )
      )
      with pytest.raises(TypeError, match=err_msg):
          forecaster.fit(y=y)
  
file_path: skforecast/skforecast/ForecasterBaseline/tests/test_fit.py
imports: import re
  import pytest
  import numpy
  import pandas
  from pandas.tseries.offsets import DateOffset
  from skforecast.ForecasterBaseline import ForecasterEquivalentDate
label_desc: Use image node_id 1 for calling a global function with example usage: test_fit_TypeError_offset_DateOffset_y_index_not_DatetimeIndex(y) without return types