code: def test_add_categories_losing_dtype_information(self):
      # GH#48812
      cat = Categorical(Series([1, 2], dtype="Int64"))
      ser = Series([4], dtype="Int64")
      result = cat.add_categories(ser)
      expected = Categorical(
          Series([1, 2], dtype="Int64"),
          categories=Series([1, 2, 4], dtype="Int64"),
      )
      tm.assert_categorical_equal(result, expected)
  
      cat = Categorical(Series(["a", "b", "a"], dtype=StringDtype()))
      ser = Series(["d"], dtype=StringDtype())
      result = cat.add_categories(ser)
      expected = Categorical(
          Series(["a", "b", "a"], dtype=StringDtype()),
          categories=Series(["a", "b", "d"], dtype=StringDtype()),
      )
      tm.assert_categorical_equal(result, expected)
  
imports: import re
  import numpy
  import pytest
  from pandas.compat import PY311
  from pandas import Categorical, CategoricalIndex, DataFrame, Index, Series, StringDtype
  import pandas._testing
  from pandas.core.arrays.categorical import recode_for_categories
label_desc: Use image node_id 12 for calling the TestCategoricalAPI obj's underlying member method code with example usage: obj.test_add_categories_losing_dtype_information() without return types