code: def test_astype_tz_conversion(self):
      # GH 35973
      val = {
          "tz": date_range(
              "2020-08-30", freq="d", periods=2, tz="Europe/London"
          )
      }
      df = DataFrame(val)
      result = df.astype({"tz": "datetime64[ns, Europe/Berlin]"})
  
      expected = df
      expected["tz"] = expected["tz"].dt.tz_convert("Europe/Berlin")
      tm.assert_frame_equal(result, expected)
  
imports: import re
  import numpy
  import pytest
  import pandas.util._test_decorators
  import pandas
  from pandas import Categorical, CategoricalDtype, DataFrame, DatetimeTZDtype, Index, Interval, IntervalDtype, NaT, Series, Timedelta, Timestamp, concat, date_range, option_context
  import pandas._testing
label_desc: Use image node_id 34 for calling the TestAstype obj's underlying member method code with example usage: obj.test_astype_tz_conversion() without return types