how to test when correct output is "random"?

[Skip Montanaro]

    Jeff> I'd like to use this project as an opportunity to teach myself
    Jeff> something about testing methodology, but since the output is based
    Jeff> on a random number generator, how can the normal "unit test" or
    Jeff> "doctest" tools work for me?

Seed the rng with the same starting value.  I believe you will always get
the same sequence:

    >>> random.seed(42)
    >>> random.random()
    0.63942679845788375
    >>> random.random()
    0.025010755222666936
    >>> random.random()
    0.27502931836911926
    >>> random.seed(42)
    >>> random.random()
    0.63942679845788375
    >>> random.random()
    0.025010755222666936
    >>> random.random()
    0.27502931836911926

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