New submission from Kevin Jamieson <kjamie...@qumulo.com>:
In Python 3.8 and later creating a mock with a spec specifying an object
containing a property that happens to raise an exception when accessed will
fail, because _mock_add_spec calls getattr() on every attribute of the spec.
This did not happen in Python 3.6/3.7.
This is likely a fairly unusual scenario (and in the particular case where I
encountered this I could just use a class instead of an instance for the spec),
but it was surprising.
For example:
# cat test.py
from unittest import mock
class Foo:
@property
def bar(self) -> str:
raise Exception('xxx')
m = mock.MagicMock(spec=Foo())
# python3.11 test.py
Traceback (most recent call last):
File "/root/test.py", line 8, in <module>
m = mock.MagicMock(spec=Foo())
^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.11/unittest/mock.py", line 2069, in __init__
_safe_super(MagicMixin, self).__init__(*args, **kw)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.11/unittest/mock.py", line 1087, in __init__
_safe_super(CallableMixin, self).__init__(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.11/unittest/mock.py", line 442, in __init__
self._mock_add_spec(spec, spec_set, _spec_as_instance, _eat_self)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.11/unittest/mock.py", line 497, in _mock_add_spec
if iscoroutinefunction(getattr(spec, attr, None)):
^^^^^^^^^^^^^^^^^^^^^^^^^
File "/root/test.py", line 6, in bar
raise Exception('xxx')
^^^^^^^^^^^^^^^^^^^^^^
Exception: xxx
----------
messages: 405982
nosy: kjamieson
priority: normal
severity: normal
status: open
title: mock raises exception when using a spec with an attribute that raises
exception on access
type: behavior
versions: Python 3.10, Python 3.11, Python 3.8, Python 3.9
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue45756>
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