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gh-91803: Mock - fix error when using autospec methods with seal #92213

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Merged
cjw296 merged 12 commits into from
Nov 7, 2022
Merged

gh-91803: Mock - fix error when using autospec methods with seal #92213

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de27032
fix mocked autospec methods with seal
akulakov May 3, 2022
96c516a
add test
akulakov May 3, 2022
0a4a359
remove stray comment
akulakov May 3, 2022
7bda679
Merge branch 'main' into 91803-Fix-seal-with-autospec-methods
akulakov May 3, 2022
8f81849
add news
akulakov May 3, 2022
1e1f45d
Merge branch '91803-Fix-seal-with-autospec-methods' of github.com:aku…
akulakov May 3, 2022
6992de7
add comment
akulakov May 3, 2022
36a47d0
use child_klass instead of Mock
akulakov May 24, 2022
dfe90da
Merge branch 'main' into 91803-Fix-seal-with-autospec-methods
akulakov Jun 22, 2022
b1b12ab
Update Lib/test/test_unittest/testmock/testsealable.py
akulakov Jun 25, 2022
c535efb
expand unittest autospec seal() test
akulakov Jul 3, 2022
dbb8bf9
Merge branch 'main' into 91803-Fix-seal-with-autospec-methods
iritkatriel Nov 6, 2022
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1 change: 1 addition & 0 deletions Lib/unittest/mock.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2731,6 +2731,7 @@ def create_autospec(spec, spec_set=False, instance=False, _parent=None,
_new_parent=parent,
**kwargs)
mock._mock_children[entry] = new
new.return_value = Mock()
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@tirkarthi tirkarthi May 21, 2022

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This could use the child_klass to construct the mock object instead of Mock. This can break code that depended on the return value being an instance of child_klass. Example case as below :

from unittest.mock import create_autospec, seal

class Foo:

    def bar(self):
        pass

spec = create_autospec(Foo)
print(spec.bar())
print(len(spec.bar()))

Python 3.10

python3.10 gh92213.py  
<MagicMock name='mock.bar()' id='140499591708000'>
0

With patch

./python gh92213.py
<Mock name='mock.bar()' id='140578691284304'>
Traceback (most recent call last):
  File "/home/karthikeyan/stuff/python/cpython/gh92213.py", line 10, in <module>
    print(len(spec.bar()))
          ^^^^^^^^^^^^^^^
TypeError: object of type 'Mock' has no len()

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@akulakov akulakov May 24, 2022

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That makes sense to me, I used Mock originally because I wasn't sure if MagicMock might "evade" seal() if set explicitly, but I tested it and it does not:

class Foo:
    x = 1
    def foo(self) -> int:
        return 0
foo=Foo()
foo = mock.create_autospec(foo)
foo.foo().x

==> AttributeError: mock.foo().x

I've pushed the update to use child_klass()

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@cjw296 cjw296 Jun 29, 2022

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@akulakov - rather than just manually testing this, please can you add a test to the test suite to ensure it doesn't change in the future?

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@akulakov akulakov Jul 3, 2022

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@cjw296 that makes sense, I've expanded the unit test - thanks for noting this.

_check_signature(original, new, skipfirst=skipfirst)

# so functions created with _set_signature become instance attributes,
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3 changes: 1 addition & 2 deletions Lib/unittest/test/testmock/testsealable.py
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Expand Up @@ -199,6 +199,7 @@ def ban(self):
self.assertIsInstance(foo.Baz, mock.MagicMock)
self.assertIsInstance(foo.Baz.baz, mock.NonCallableMagicMock)
self.assertIsInstance(foo.Baz.ban, mock.MagicMock)
self.assertIsInstance(foo.bar2(), mock.Mock)

self.assertEqual(foo.bar1(), 'a')
foo.bar1.return_value = 'new_a'
Expand All @@ -211,8 +212,6 @@ def ban(self):
foo.foo()
with self.assertRaises(AttributeError):
foo.bar = 1
with self.assertRaises(AttributeError):
foo.bar2()
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@cjw296 cjw296 May 9, 2022

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I'm guessing @sobolevn or @corona10 added this assertion for a reason, perhaps they could comment?

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@AlexWaygood AlexWaygood May 9, 2022

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I think Nikita is largely on a break from open-source stuff right now FYI

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@tirkarthi tirkarthi May 21, 2022

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I feel this is an incorrect assert since bar2 method is present on Foo and shouldn't raise. Removing the assert statement the AttributeError here asserted is for the exception that return_value is not found due to seal which this PR fixes and not that bar2 is not found.

./python Lib/unittest/test/testmock/testsealable.py
..............EE....
======================================================================
ERROR: test_seal_with_autospec (__main__.TestSealable.test_seal_with_autospec) (spec_set=True)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/karthikeyan/stuff/python/cpython/Lib/unittest/test/testmock/testsealable.py", line 215, in test_seal_with_autospec
    foo.bar2()
    ^^^^^^^^^^
  File "/home/karthikeyan/stuff/python/cpython/Lib/unittest/mock.py", line 1108, in __call__
    return self._mock_call(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/karthikeyan/stuff/python/cpython/Lib/unittest/mock.py", line 1112, in _mock_call
    return self._execute_mock_call(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/karthikeyan/stuff/python/cpython/Lib/unittest/mock.py", line 1184, in _execute_mock_call
    return self.return_value
           ^^^^^^^^^^^^^^^^^
  File "/home/karthikeyan/stuff/python/cpython/Lib/unittest/mock.py", line 638, in __getattr__
    raise AttributeError("Mock object has no attribute %r" % name)
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: Mock object has no attribute 'return_value'

======================================================================
ERROR: test_seal_with_autospec (__main__.TestSealable.test_seal_with_autospec) (spec_set=False)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/karthikeyan/stuff/python/cpython/Lib/unittest/test/testmock/testsealable.py", line 215, in test_seal_with_autospec
    foo.bar2()
    ^^^^^^^^^^
  File "/home/karthikeyan/stuff/python/cpython/Lib/unittest/mock.py", line 1108, in __call__
    return self._mock_call(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/karthikeyan/stuff/python/cpython/Lib/unittest/mock.py", line 1112, in _mock_call
    return self._execute_mock_call(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/karthikeyan/stuff/python/cpython/Lib/unittest/mock.py", line 1184, in _execute_mock_call
    return self.return_value
           ^^^^^^^^^^^^^^^^^
  File "/home/karthikeyan/stuff/python/cpython/Lib/unittest/mock.py", line 638, in __getattr__
    raise AttributeError("Mock object has no attribute %r" % name)
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: Mock object has no attribute 'return_value'

----------------------------------------------------------------------
Ran 19 tests in 0.121s

FAILED (errors=2)


foo.bar2.return_value = 'bar2'
self.assertEqual(foo.bar2(), 'bar2')
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Library/2022-05-03-11-32-29.gh-issue-91803.pI4Juv.rst
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@@ -0,0 +1,3 @@
Fix an error when using a method of objects mocked with
:func:`unittest.mock.create_autospec` after it was sealed with
:func:`unittest.mock.seal` function.