Remove use of StringIO in test, just get returned value instead

Author: kinow

pandas/tests/io/formats/test_to_csv.py

@@ -4,8 +4,6 @@
 import numpy as np
 import pytest
 
-from pandas.compat import StringIO
-
 import pandas as pd
 from pandas import DataFrame, compat
 from pandas.util import testing as tm
@@ -570,8 +568,6 @@ def test_to_csv_na_rep_long_string(self, df_value, df_new_type):
                          'mynull']
         expected = tm.convert_rows_list_to_csv_str(expected_rows)
 
-        csv_data = StringIO()
-        df.to_csv(csv_data, index=False, na_rep='mynull', encoding='ascii')
-        result = csv_data.getvalue()
+        result = df.to_csv(index=False, na_rep='mynull', encoding='ascii')
 
         assert expected == result