code: def test_format(self):
      # GH#35439
      idx = pd.date_range("20130101", periods=5)
      expected = [f"{x:%Y-%m-%d}" for x in idx]
      msg = r"DatetimeIndex\.format is deprecated"
      with tm.assert_produces_warning(FutureWarning, match=msg):
          assert idx.format() == expected
  
imports: from datetime import datetime
  import dateutil.tz
  import numpy
  import pytest
  import pytz
  import pandas
  from pandas import DatetimeIndex, NaT, Series
  import pandas._testing
label_desc: Use image node_id 1 for calling the TestFormat obj's underlying member method code with example usage: obj.test_format() without return types