class_docstr: Various Series and DataFrame methods.
class_docstr_tok: ["Various","Series","and","DataFrame","methods","."]
code: def test_fillna_copy_frame(self, data_missing):
      arr = data_missing.take([1, 1])
      df = pd.DataFrame({"A": arr})
      df_orig = df.copy()
  
      filled_val = df.iloc[0, 0]
      result = df.fillna(filled_val)
  
      result.iloc[0, 0] = filled_val
  
      tm.assert_frame_equal(df, df_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 26 for calling the BaseMethodsTests obj's underlying member method code with example usage: obj.test_fillna_copy_frame(data_missing) without return types