code: def test_astype_datetime64tz(self):
      ser = Series(date_range("20130101", periods=3, tz="US/Eastern"))
  
      # astype
      result = ser.astype(object)
      expected = Series(ser.astype(object), dtype=object)
      tm.assert_series_equal(result, expected)
  
      result = (
          Series(ser.values)
          .dt.tz_localize("UTC")
          .dt.tz_convert(ser.dt.tz)
      )
      tm.assert_series_equal(result, ser)
  
      # astype - object, preserves on construction
      result = Series(ser.astype(object))
      expected = ser.astype(object)
      tm.assert_series_equal(result, expected)
  
      # astype - datetime64[ns, tz]
      msg = "Cannot use .astype to convert from timezone-naive"
      with pytest.raises(TypeError, match=msg):
          # dt64->dt64tz astype deprecated
          Series(ser.values).astype("datetime64[ns, US/Eastern]")
  
      with pytest.raises(TypeError, match=msg):
          # dt64->dt64tz astype deprecated
          Series(ser.values).astype(ser.dtype)
  
      result = ser.astype("datetime64[ns, CET]")
      expected = Series(
          date_range("20130101 06:00:00", periods=3, tz="CET")
      )
      tm.assert_series_equal(result, expected)
  
imports: from datetime import datetime, timedelta
  from importlib import reload
  import string
  import sys
  import numpy
  import pytest
  from pandas._libs.tslibs import iNaT
  import pandas.util._test_decorators
  from pandas import NA, Categorical, CategoricalDtype, DatetimeTZDtype, Index, Interval, NaT, Series, Timedelta, Timestamp, cut, date_range, to_datetime
  import pandas._testing
label_desc: Use image node_id 11 for calling the TestAstype obj's underlying member method code with example usage: obj.test_astype_datetime64tz() without return types