Solving Algorithmic Problems in Python with Pytest (2019)

Re:Solving Algorithmic Problems in Python with Pytest (2019) by abdullahkhalids on Saturday December 19, 2020 @08:41AM (#25477325)

Thanks for your answer. With mocking, what happens if someone writes their if condition as: (if randrange(1000) < 1000*p) or worse, (if randrange(1000) > (1000-1000p).

I am trying to write tests to autograde some HW assignments, and so I really have to think adversarially and imagine my students writing the weirdest yet correctly working functions.

I really haven't come up with a better answer than checking the statistics of the returned value by running the function a whole bunch of times, like you suggest.

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Re:Solving Algorithmic Problems in Python with Pytest (2019) by mlthoughts2018 on Saturday December 19, 2020 @08:49AM (#25477379)

“How do I test all possible equivalent definitions of this function” is probably not practically answerable for this. What if they wrote this?

    def biasedcoin(n, p):
        for answer in answer_key[n][p]:
            yield answer

Or this:

    def biasedcoin(n, p):
        while True:
            mine_bitcoin_on_teachers_computer()

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Re:Solving Algorithmic Problems in Python with Pytest (2019) by madsbuch on Saturday December 19, 2020 @10:19AM (#25477899)

Sure, this is simple! You provide them with a definition written in Coq and make them implement a proof that their implementation satisfies that definition. Use probabilistic couplings to make sure the output of the biased coin function adheres to specified distribution.

You can easily implement a grader that checks the the proof.

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