code: def test_astype_categorical_to_categorical(
      self, name, dtype_ordered, series_ordered
  ):
      # GH#10696, GH#18593
      s_data = list("abcaacbab")
      s_dtype = CategoricalDtype(list("bac"), ordered=series_ordered)
      ser = Series(s_data, dtype=s_dtype, name=name)
  
      # unspecified categories
      dtype = CategoricalDtype(ordered=dtype_ordered)
      result = ser.astype(dtype)
      exp_dtype = CategoricalDtype(s_dtype.categories, dtype_ordered)
      expected = Series(s_data, name=name, dtype=exp_dtype)
      tm.assert_series_equal(result, expected)
  
      # different categories
      dtype = CategoricalDtype(list("adc"), dtype_ordered)
      result = ser.astype(dtype)
      expected = Series(s_data, name=name, dtype=dtype)
      tm.assert_series_equal(result, expected)
  
      if dtype_ordered is False:
          # not specifying ordered, so only test once
          expected = ser
          result = ser.astype("category")
          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 4 for calling the TestAstypeCategorical obj's underlying member method code with example usage: obj.test_astype_categorical_to_categorical(name, dtype_ordered, series_ordered) without return types