class_docstr: Various Series and DataFrame methods.
class_docstr_tok: ["Various","Series","and","DataFrame","methods","."]
code: def test_fillna_copy_series(self, data_missing):
      arr = data_missing.take([1, 1])
      ser = pd.Series(arr, copy=False)
      ser_orig = ser.copy()
  
      filled_val = ser[0]
      result = ser.fillna(filled_val)
      result.iloc[0] = filled_val
  
      tm.assert_series_equal(ser, ser_orig)
  
imports: import inspect
  import operator
  import numpy
  import pytest
  from pandas._typing import Dtype
  from pandas.core.dtypes.common import is_bool_dtype
  from pandas.core.dtypes.dtypes import NumpyEADtype
  from pandas.core.dtypes.missing import na_value_for_dtype
  import pandas
  import pandas._testing
  from pandas.core.sorting import nargsort
label_desc: Use image node_id 27 for calling the BaseMethodsTests obj's underlying member method code with example usage: obj.test_fillna_copy_series(data_missing) without return types