code: def test_to_csv_with_single_column(self):
      # see gh-18676, https://bugs.python.org/issue32255
      #
      # Python's CSV library adds an extraneous '""'
      # before the newline when the NaN-value is in
      # the first row. Otherwise, only the newline
      # character is added. This behavior is inconsistent
      # and was patched in https://bugs.python.org/pull_request4672.
      df1 = DataFrame([None, 1])
      expected1 = """\
  ""
  1.0
  """
      with tm.ensure_clean("test.csv") as path:
          df1.to_csv(path, header=None, index=None)
          with open(path, encoding="utf-8") as f:
              assert f.read() == expected1
  
      df2 = DataFrame([1, None])
      expected2 = """\
  1.0
  ""
  """
      with tm.ensure_clean("test.csv") as path:
          df2.to_csv(path, header=None, index=None)
          with open(path, encoding="utf-8") as f:
              assert f.read() == expected2
  
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 1 for calling the TestToCSV obj's underlying member method code with example usage: obj.test_to_csv_with_single_column() without return types