[Python-checkins] Fix test_generators: save/restore warnings filters (#108246)

[vstinner]

https://github.com/python/cpython/commit/531930f47f6b2a548d31e62cb4ad3e215a24bf53
commit: 531930f47f6b2a548d31e62cb4ad3e215a24bf53
branch: main
author: Victor Stinner <vstinner at python.org>
committer: vstinner <vstinner at python.org>
date: 2023-08-21T23:41:13Z
summary:

Fix test_generators: save/restore warnings filters (#108246)

Previously, depending on existing filters, the test
could modify the warnings and so fail as "env changed".

files:
M Lib/test/test_generators.py

diff --git a/Lib/test/test_generators.py b/Lib/test/test_generators.py
index a8a344ab8de48..d48f0d47ba196 100644
--- a/Lib/test/test_generators.py
+++ b/Lib/test/test_generators.py
@@ -2258,6 +2258,7 @@ def printsolution(self, x):
 caught ValueError (xyz)
 
 >>> import warnings
+>>> old_filters = warnings.filters.copy()
 >>> warnings.filterwarnings("ignore", category=DeprecationWarning)
 
 # Filter DeprecationWarning: regarding the (type, val, tb) signature of throw().
@@ -2331,8 +2332,7 @@ def printsolution(self, x):
   ...
 ValueError: 7
 
->>> warnings.filters.pop(0)
-('ignore', None, <class 'DeprecationWarning'>, None, 0)
+>>> warnings.filters[:] = old_filters
 
 # Re-enable DeprecationWarning: the (type, val, tb) exception representation is deprecated,
 #                               and may be removed in a future version of Python.