bpo-29620: iterate over a copy of sys.modules (GH-4800)
unittest.TestCase.assertWarns no longer raises a RuntimeException
when accessing a module's ``__warningregistry__`` causes importation of a new
module, or when a new module is imported in another thread.
Patch by Kernc.
diff --git a/Lib/unittest/case.py b/Lib/unittest/case.py
index f8bc865..52eb7d0 100644
--- a/Lib/unittest/case.py
+++ b/Lib/unittest/case.py
@@ -252,7 +252,7 @@
def __enter__(self):
# The __warningregistry__'s need to be in a pristine state for tests
# to work properly.
- for v in sys.modules.values():
+ for v in list(sys.modules.values()):
if getattr(v, '__warningregistry__', None):
v.__warningregistry__ = {}
self.warnings_manager = warnings.catch_warnings(record=True)