Unitest.mock.MagicMock raises a StopIteration - not following PEP 479

[jkatzur]

It looks like Unitest.mock.MagicMock raises a StopIteration when repeated calls to the mock are made and an iterable is exhausted. After Python 3.7+, due to PEP 479, this raises a Runtime Error. This makes unit tests that worked in Python 3.6 fail, including any list comprehensions on MagicMock results. These can be easily caught with a try/except, but it's a bit clunky.

According to PEP 479 instead of StopIteration MagicMock should just return return when the iterable is exhausted. See here: https://peps.python.org/pep-0479/

Please let me know if I missed something on my end. Thanks for looking into this.

[tirkarthi]

This might be backwards incompatible as raising StopIteration is explicitly documented. Maybe the documentation can be updated to note how this differs from PEP 479.

https://docs.python.org/3/library/unittest.mock.html#calling

The side_effect can also be any iterable object. Repeated calls to the mock will return values from the iterable (until the iterable is exhausted and a StopIteration is raised):