python_dunder_new_assignmment_bug.py

class SomeClassToMock(object):
    def __init__(self, key=None):
        self.key = key

old_new, SomeClassToMock.__new__ = SomeClassToMock.__new__, lambda: None
SomeClassToMock.__new__ = old_new
SomeClassToMock(key='value')

run.log

$ python2.7 python_dunder_new_assignmment_bug.py && echo $?
0
$ python3.2 python_dunder_new_assignmment_bug.py && echo $?
0
$ python3.3 python_dunder_new_assignmment_bug.py && echo $?
Traceback (most recent call last):
  File "python_dunder_new_assignmment_bug.py", line 7, in <module>
    SomeClassToMock(key='value')
TypeError: object() takes no parameters
$ python3.6 python_dunder_new_assignmment_bug.py && echo $?
Traceback (most recent call last):
  File "python_dunder_new_assignmment_bug.py", line 7, in <module>
    SomeClassToMock(key='value')
TypeError: object() takes no parameters
$ python3.7 python_dunder_new_assignmment_bug.py && echo $?
Traceback (most recent call last):
  File "python_dunder_new_assignmment_bug.py", line 7, in <module>
    SomeClassToMock(key='value')
TypeError: object.__new__() takes exactly one argument (the type to instantiate)
$ python3.10 python_dunder_new_assignmment_bug.py && echo $?
Traceback (most recent call last):
  File "python_dunder_new_assignmment_bug.py", line 7, in <module>
    SomeClassToMock(key='value')
TypeError: object.__new__() takes exactly one argument (the type to instantiate)