unitest.mock: Using autospec=True conflicts with 'wraps' #75988
Comments
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If have autospec=True, then no ValueError is raised. If autospec=False or not defined, then the ValueError is raised. import sys
from unittest import mock
def wrapped_func(value):
raise ValueError(value)@mock.patch('__main__.wrapped_func', autospec=True, wraps=wrapped_func) wrapped_func("testing")
if '__main__' == __name__:
sys.exit(main()) |
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I can reproduce the problem and have analyzed it a bit. My use case is a bit different, I want to use autospec=True and wraps= so that I can mock unbound methods but return the result from the original method (see also https://docs.python.org/3/library/unittest.mock-examples.html#mocking-unbound-methods). The problem in the mock code is that mock.return_value actually calls __get_return_value() which replaces the actual return value mock.DEFAULT (which is stored in self._mock_return_value) with a new child mock. When the mock is then called and _mock_call() is executed, the wrapped function is not executed because self._mock_return_value is not mock.DEFAULT anymore: if (self._mock_wraps is not None and
self._mock_return_value is DEFAULT):
return self._mock_wraps(*args, **kwargs)
if ret_val is DEFAULT:
ret_val = self.return_value
return ret_valSince self._mock_return_value is not DEFAULT anymore it doesn't matter if the mock wraps something and it will instead just return a new mock. I think that the side effect of the assignment to self.return_value in _setup_func() is not intentional, i.e. the child mock should actually be created only if there is an outside access to return_value, but not when it is just wrapped in a function. The assignment can be made side effect free by assigning the internal attribute _mock_return_value (see attached patch). This solves the problem for me. I've attached a patch that fixes the problem and doesn't seem to introduce a regression (all unittest.mock tests pass). If somebody is interested in getting this merged, I'm happy to provide a regression test and everything else that is needed to get this merged. Cheers, Lukas |
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Hi, I just wanted to ask what the status for this bug is. I'm still interested in getting this merged and would be happy to help. Lukas |
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I ran into the same issue with methods like @Lukas0907 described it, on Python 3.10. |
* set default return value of functional types as _mock_return_value * added test of wrapping child attributes * added backward compatibility with explicit return * added docs on the order of precedence * added test to check default return_value
…hon#115223) * set default return value of functional types as _mock_return_value * added test of wrapping child attributes * added backward compatibility with explicit return * added docs on the order of precedence * added test to check default return_value (cherry picked from commit 735fc2c)
…hon#115223) * set default return value of functional types as _mock_return_value * added test of wrapping child attributes * added backward compatibility with explicit return * added docs on the order of precedence * added test to check default return_value (cherry picked from commit 735fc2c)
…-115223) (#117119) gh-75988: Fix issues with autospec ignoring wrapped object (#115223) * set default return value of functional types as _mock_return_value * added test of wrapping child attributes * added backward compatibility with explicit return * added docs on the order of precedence * added test to check default return_value (cherry picked from commit 735fc2c)
…-115223) (#117124) gh-75988: Fix issues with autospec ignoring wrapped object (#115223) * set default return value of functional types as _mock_return_value * added test of wrapping child attributes * added backward compatibility with explicit return * added docs on the order of precedence * added test to check default return_value (cherry picked from commit 735fc2c)
…hon#115223) * set default return value of functional types as _mock_return_value * added test of wrapping child attributes * added backward compatibility with explicit return * added docs on the order of precedence * added test to check default return_value
…hon#115223) * set default return value of functional types as _mock_return_value * added test of wrapping child attributes * added backward compatibility with explicit return * added docs on the order of precedence * added test to check default return_value
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