code: def test_to_csv_default_encoding(self):
      # GH17097
      df = DataFrame({"col": ["AAAAA", "ÄÄÄÄÄ", "ßßßßß", "聞聞聞聞聞"]})
  
      with tm.ensure_clean("test.csv") as path:
          # the default to_csv encoding is uft-8.
          df.to_csv(path)
          tm.assert_frame_equal(pd.read_csv(path, index_col=0), df)
  
imports: import io
  import os
  import sys
  from zipfile import ZipFile
  from _csv import Error
  import numpy
  import pytest
  import pandas
  from pandas import DataFrame, Index, compat
  import pandas._testing
label_desc: Use image node_id 2 for calling the TestToCSV obj's underlying member method code with example usage: obj.test_to_csv_default_encoding() without return types