docstr: Binary file objects should honor a specified encoding.
  
  GH 23854 and GH 13068 with binary handles
docstr_tok: ["Binary","file","objects","should","honor","a","specified","encoding",".","GH","23854","and","GH","13068","with","binary","handles"]
code: def test_to_csv_encoding_binary_handle(self, mode):
      """
      Binary file objects should honor a specified encoding.
  
      GH 23854 and GH 13068 with binary handles
      """
      # example from GH 23854
      content = "a, b, 🐟".encode("utf-8-sig")
      buffer = io.BytesIO(content)
      df = pd.read_csv(buffer, encoding="utf-8-sig")
  
      buffer = io.BytesIO()
      df.to_csv(buffer, mode=mode, encoding="utf-8-sig", index=False)
      buffer.seek(0)  # tests whether file handle wasn't closed
      assert buffer.getvalue().startswith(content)
  
      # example from GH 13068
      with tm.ensure_clean() as path:
          with open(path, "w+b") as handle:
              DataFrame().to_csv(
                  handle, mode=mode, encoding="utf-8-sig"
              )
  
              handle.seek(0)
              assert handle.read().startswith(b'\xef\xbb\xbf""')
  
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 35 for calling the TestToCSV obj's underlying member method code with example usage: obj.test_to_csv_encoding_binary_handle(mode) without return types