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paul-butcher/patch_methods.py

Created June 16, 2021 08:12
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  1. paul-butcher created this gist Jun 16, 2021.
    44 changes: 44 additions & 0 deletions patch_methods.py
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,44 @@
    from unittest import mock
    ​
    class MyClass:
    def __init__(self):
    print('hello')
    self.my_property = 'dolly'
    ​
    def do_something(self):
    print('world')
    ​
    def do_something_else(self):
    print(self.my_property)
    ​
    def do_yet_another_thing(self):
    print(f"goodbye {self.do_something()}")
    ​
    ​
    print('exercise the class normally:')
    o = MyClass()
    o.do_something()
    o.do_something_else()
    o.do_yet_another_thing()
    ​
    ​
    print('\nexercise the patched class:')
    with mock.patch.object(MyClass, '__init__', return_value=None):
    # Note that it does not say "hello" at this point
    o2 = MyClass()
    ​
    # Here, it prints "world"
    o2.do_something()
    # If the real function you are exercising relies on
    # properties set in __init__, you will have to
    # set them here instead.
    o2.my_property = "Is it me you're looking for"
    o2.do_something_else()
    ​
    # You can patch any methods.
    # Using the context manager means that the patch disappears
    # when no longer in scope
    with mock.patch.object(MyClass, 'do_something', return_value="banana"):
    o2.do_yet_another_thing() # goodbye banana
    ​
    o2.do_yet_another_thing() # goodbye None