fix tests for py.test running on CPython v3.10.0b3

1 files changed, 3 insertions, 7 deletions

diff --git a/testing/cffi0/test_function.py b/testing/cffi0/test_function.py
index 4f2c864..b4bb23d 100644
--- a/testing/cffi0/test_function.py
+++ b/testing/cffi0/test_function.py
@@ -5,7 +5,7 @@ import math, os, sys
 import ctypes.util
 from cffi.backend_ctypes import CTypesBackend
 from testing.udir import udir
-from testing.support import FdWriteCapture
+from testing.support import FdWriteCapture, StdErrCapture
 from .backend_tests import needs_dlopen_none
 
 try:
@@ -227,13 +227,9 @@ class TestFunction(object):
             def cb():
                 return returnvalue
             fptr = ffi.callback("void(*)(void)", cb)
-            old_stderr = sys.stderr
-            try:
-                sys.stderr = StringIO()
+            with StdErrCapture() as f:
                 returned = fptr()
-                printed = sys.stderr.getvalue()
-            finally:
-                sys.stderr = old_stderr
+            printed = f.getvalue()
             assert returned is None
             if returnvalue is None:
                 assert printed == ''