Mini-Quickcheck for Python

I wanted an implementation of a mini-Quickcheck in Python. This is the API I came up with. It is also a good way to see what’s at the heart of Quicheck: generators.

I cut every corner I could. Some methods are not random, but this can be easily fixed.

There is a runner decorator (dependent on the decorator library) than run’s test methods repeatedly.

import random

def oneof(*values):
    return random.choice(values)

def optional(param):
    return oneof(None, param)

def boolean():
    return oneof(True, False)

def integer(min=0,max=1<<30):
    return random.randint(min,max)

def char():
    return chr(integer(min=2,max=ord('z')))

def string(min=0):
    return "".join([char() for _ in xrange(integer(min=min, max=10))])

def nonempty_string():
    return string(min=1)

def substring(string):
    if not string:
           return string
    start = integer(0, len(string) - 1)
    end = start + integer(len(string) - start)
    return string[start:end]

def date():
    return datetime.date.today()

def subset(*vs):
    return [e for e in vs if boolean()]

def list(gen):
    return [gen() for _ in xrange(integer(max=5))]
    
@decorator
def runner(func, *args, **kwargs):
    for r in xrange(4):
        test_instance = args[0]