code: def test_shift_by_offset(self, datetime_frame, frame_or_series):
      # shift by DateOffset
      obj = tm.get_obj(datetime_frame, frame_or_series)
      offset = offsets.BDay()
  
      shifted = obj.shift(5, freq=offset)
      assert len(shifted) == len(obj)
      unshifted = shifted.shift(-5, freq=offset)
      tm.assert_equal(unshifted, obj)
  
      shifted2 = obj.shift(5, freq="B")
      tm.assert_equal(shifted, shifted2)
  
      unshifted = obj.shift(0, freq=offset)
      tm.assert_equal(unshifted, obj)
  
      d = obj.index[0]
      shifted_d = d + offset * 5
      if frame_or_series is DataFrame:
          tm.assert_series_equal(
              obj.xs(d), shifted.xs(shifted_d), check_names=False
          )
      else:
          tm.assert_almost_equal(obj.at[d], shifted.at[shifted_d])
  
imports: import numpy
  import pytest
  import pandas
  from pandas import CategoricalIndex, DataFrame, Index, NaT, Series, date_range, offsets
  import pandas._testing
label_desc: Use image node_id 14 for calling the TestDataFrameShift obj's underlying member method code with example usage: obj.test_shift_by_offset(datetime_frame, frame_or_series) without return types