test: update test_support

deantvv · deantvv · commit 4ba36116643f · 2021-11-28T20:51:33.000+08:00
diff --git a/Lib/test/test_support.py b/Lib/test/test_support.py
@@ -642,14 +642,8 @@ def test_fd_count(self):
 
     def check_print_warning(self, msg, expected):
         stderr = io.StringIO()
-
-        old_stderr = sys.__stderr__
-        try:
-            sys.__stderr__ = stderr
+        with support.swap_attr(support.print_warning, 'orig_stderr', stderr):
             support.print_warning(msg)
-        finally:
-            sys.__stderr__ = old_stderr
-
         self.assertEqual(stderr.getvalue(), expected)
 
     def test_print_warning(self):
