bpo-40275: Use new test.support helper submodules in tests (GH-21449)

diff --git a/Lib/test/test_configparser.py b/Lib/test/test_configparser.py
index f16da11..230ffc1 100644
--- a/Lib/test/test_configparser.py
+++ b/Lib/test/test_configparser.py
@@ -8,6 +8,7 @@
 import warnings
 
 from test import support
+from test.support import os_helper
 
 
 class SortedDict(collections.UserDict):
@@ -1063,17 +1064,17 @@
             cf.add_section(s)
             for j in range(10):
                 cf.set(s, 'lovely_spam{}'.format(j), self.wonderful_spam)
-        with open(support.TESTFN, 'w') as f:
+        with open(os_helper.TESTFN, 'w') as f:
             cf.write(f)
 
     def tearDown(self):
-        os.unlink(support.TESTFN)
+        os.unlink(os_helper.TESTFN)
 
     def test_dominating_multiline_values(self):
         # We're reading from file because this is where the code changed
         # during performance updates in Python 3.2
         cf_from_file = self.newconfig()
-        with open(support.TESTFN) as f:
+        with open(os_helper.TESTFN) as f:
             cf_from_file.read_file(f)
         self.assertEqual(cf_from_file.get('section8', 'lovely_spam4'),
                          self.wonderful_spam.replace('\t\n', '\n'))