MagicMock initializer fails for magic methods

[berdario]

BPO	23310
Nosy	@rbtcollins, @voidspace, @ambv, @ChillarAnand
Files	test_mock.py: sample test fix_magic_in_init.diff: Tests for this bug + proposed fix. fix_magic_in_init_v2.diff

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/ambv'
closed_at = <Date 2015-04-14.07:19:28.092>
created_at = <Date 2015-01-24.17:20:39.542>
labels = ['type-bug', 'library']
title = 'MagicMock initializer fails for magic methods'
updated_at = <Date 2015-04-14.07:24:37.325>
user = 'https://bugs.python.org/berdario'

bugs.python.org fields:

activity = <Date 2015-04-14.07:24:37.325>
actor = 'lukasz.langa'
assignee = 'lukasz.langa'
closed = True
closed_date = <Date 2015-04-14.07:19:28.092>
closer = 'lukasz.langa'
components = ['Library (Lib)']
creation = <Date 2015-01-24.17:20:39.542>
creator = 'berdario'
dependencies = []
files = ['38654', '38919', '38922']
hgrepos = []
issue_num = 23310
keywords = ['patch']
message_count = 8.0
messages = ['234623', '239013', '240623', '240626', '240631', '240844', '240853', '240854']
nosy_count = 7.0
nosy_names = ['rbcollins', 'michael.foord', 'lukasz.langa', 'python-dev', 'berdario', 'chillaranand', 'kjachim']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue23310'
versions = ['Python 3.4', 'Python 3.5']

[berdario]

I guess this should be expected... too much magic :P

>>> from unittest.mock import MagicMock
>>> MagicMock(**{'__hash__.return_value': "FIXME"})
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/nix/store/qlvbf3n3y34idxcgwwhsi9pq26v28q99-python3-3.4.2/lib/python3.4/unittest/mock.py", line 1772, in __init__
    _safe_super(MagicMixin, self).__init__(*args, **kw)
  File "/nix/store/qlvbf3n3y34idxcgwwhsi9pq26v28q99-python3-3.4.2/lib/python3.4/unittest/mock.py", line 881, in __init__
    _spec_state, _new_name, _new_parent, **kwargs
  File "/nix/store/qlvbf3n3y34idxcgwwhsi9pq26v28q99-python3-3.4.2/lib/python3.4/unittest/mock.py", line 410, in __init__
    self.configure_mock(**kwargs)
  File "/nix/store/qlvbf3n3y34idxcgwwhsi9pq26v28q99-python3-3.4.2/lib/python3.4/unittest/mock.py", line 560, in configure_mock
    setattr(obj, final, val)
AttributeError: 'method-wrapper' object has no attribute 'return_value'

The same happens with e.g. __str__

>> m.configure_mock(**{'__hash__.return_value': 1})

works just fine, instead

[ChillarAnand]

mock itself fails

[kjachim]

Tests for this bug + proposed fix.

[kjachim]

For Mock both the following tests fail, I would say it is an expected behavior.

def test_setting_magic_method_for_mock(self):
    m = Mock()
    m.configure_mock(**{'__str__.return_value': "14"})
    self.assertEqual(str(m), "14")
        
def test_setting_magic_method_in_mock_initialization(self):
    m = Mock(**{'__str__.return_value': "12"})
    self.assertEqual(str(m), "12")

[kjachim]

Added more logging to the patch.

[python-dev]

New changeset 4d1236b180be by Łukasz Langa in branch 'default':
Issue bpo-23310: Fix MagicMock's initializer to work with __methods__.
https://hg.python.org/cpython/rev/4d1236b180be

[python-dev]

New changeset 8e5592a43d65 by Łukasz Langa in branch '3.4':
Issue bpo-23310: Fix MagicMock's initializer to work with __methods__.
https://hg.python.org/cpython/rev/8e5592a43d65

New changeset dd8f48ff9480 by Łukasz Langa in branch 'default':
Merge 3.4 (bpo-23310)
https://hg.python.org/cpython/rev/dd8f48ff9480

[ambv]

Awesome! Thank you for your patch, Kasia. For the record, I left the non-magic Mock behavior untouched since Kasia rightfully points out that in this case m.configure_mock() also does not work.