code: def test_calendar(self):
      calendar = USFederalHolidayCalendar()
      dt = datetime(2014, 1, 17)
      assert_offset_equal(
          CDay(calendar=calendar), dt, datetime(2014, 1, 21)
      )
  
file_path: pandas/pandas/tests/tseries/offsets/test_custom_business_day.py
imports: from datetime import datetime, timedelta
  import numpy
  import pytest
  from pandas._libs.tslibs.offsets import CDay
  from pandas import _testing, read_pickle
  from pandas.tests.tseries.offsets.common import assert_offset_equal
  from pandas.tseries.holiday import USFederalHolidayCalendar
label_desc: Use image node_id 5 for calling the TestCustomBusinessDay obj's underlying member method code with example usage: obj.test_calendar() without return types