code: def test_format_date_tz(self):
      dti = pd.to_datetime([datetime(2013, 1, 1)], utc=True)
      msg = "DatetimeIndex.format is deprecated"
      with tm.assert_produces_warning(FutureWarning, match=msg):
          formatted = dti.format()
      assert formatted[0] == "2013-01-01 00:00:00+00:00"
  
      dti = pd.to_datetime([datetime(2013, 1, 1), NaT], utc=True)
      with tm.assert_produces_warning(FutureWarning, match=msg):
          formatted = dti.format()
      assert formatted[0] == "2013-01-01 00:00:00+00:00"
  
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 6 for calling the TestFormat obj's underlying member method code with example usage: obj.test_format_date_tz() without return types