New submission from Avram <pyt...@avram.us>:
This bug was introduced with Issue25597
Here's some code that demonstrates the error:
import sys
from unittest.mock import patch
with patch.object(sys, 'stdout', wraps=sys.stdout) as mockstdout:
bool(sys.stdout)
This works fine in 3.8 and earlier, but fails in 3.9
It seems the goal was to be able to access dunder methods for wrapped objects.
Before this change __bool__ wasn't actually being checked, but was forced to
True, which works for basic existence tests. The new code method._mock_wraps =
getattr(mock._mock_wraps, name) has no fallthrough in case the attribute isn't
there such as the case with __bool__ on sys.stdout.
----------
components: Library (Lib)
messages: 364222
nosy: Darragh Bailey, anthonypjshaw, aviso, cjw296, lisroach, mariocj89,
michael.foord, pconnell, r.david.murray, rbcollins, xtreak
priority: normal
severity: normal
status: open
title: mock 3.9 bug: Wrapped objects without __bool__ raise exception
type: behavior
versions: Python 3.9
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue39966>
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