code: def test_astype_str_freq_and_tz(self):
      # test astype string with freqH and timezone
      dti = date_range(
          "3/6/2012 00:00",
          periods=2,
          freq="h",
          tz="Europe/London",
          name="test_name",
      )
      result = dti.astype(str)
      expected = Index(
          ["2012-03-06 00:00:00+00:00", "2012-03-06 01:00:00+00:00"],
          dtype=object,
          name="test_name",
      )
      tm.assert_index_equal(result, expected)
  
imports: from datetime import datetime
  import dateutil
  import numpy
  import pytest
  import pytz
  import pandas
  from pandas import DatetimeIndex, Index, NaT, PeriodIndex, Timestamp, date_range
  import pandas._testing
label_desc: Use image node_id 12 for calling the TestDatetimeIndex obj's underlying member method code with example usage: obj.test_astype_str_freq_and_tz() without return types