bpo-40275: Use new test.support helper submodules in tests (GH-21412)

diff --git a/Lib/test/test_codeop.py b/Lib/test/test_codeop.py
index 45cb1a7..6e821df6 100644
--- a/Lib/test/test_codeop.py
+++ b/Lib/test/test_codeop.py
@@ -5,6 +5,7 @@
 import sys
 import unittest
 from test import support
+from test.support import warnings_helper
 
 from codeop import compile_command, PyCF_DONT_IMPLY_DEDENT
 import io
@@ -305,7 +306,7 @@
 
     def test_warning(self):
         # Test that the warning is only returned once.
-        with support.check_warnings((".*literal", SyntaxWarning)) as w:
+        with warnings_helper.check_warnings((".*literal", SyntaxWarning)) as w:
             compile_command("0 is 0")
             self.assertEqual(len(w.warnings), 1)