code: def test_fit_y_index_not_DatetimeIndex():
      """
      Test index_freq is set correctly when y index is not a DatetimeIndex.
      """
      forecaster = ForecasterEquivalentDate(
          offset=5, n_offsets=2, agg_func=np.mean, forecaster_id=None
      )
      y = pd.Series(np.random.rand(10))
      forecaster.fit(y)
  
      assert forecaster.index_freq == y.index.step
  
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 5 for calling a global function with example usage: test_fit_y_index_not_DatetimeIndex() without return types