random_fill_testing.py

# random-fill testing:

def makes_sufficently_large_table():
    unittest.assertEqual(generate_choices([('a',2),('b',1),('c',2)]), ['a','a','b','c','c'])
    # ... similar.  Include, among others, things with fallbacks that don't get used.

def fills_small_table():
    choices = generate_choices([('a',2),('b',1),('c',0),('d',0)])
    # make sure the first part is all the ones with known frequencies
    # this actually suggests that what we really want is to break this down into more functions:
    # generate_static_choices makes the deterministic part of the table, for one thing
    unittest.assertEqual(choices[:3], ['a','a','b'])
    unittest.assertIn(choices[3], ['c','d'])
    # now if we want to go to town, do this a bunch of times
    # 30 times over for 2 fallbacks should do
    # for larger numbers of fallbacks, you'll want a somewhat larger target.
    # something something coupon collector's problem
    # but with 30 tries we have approx. a 1 in a billion chance of it failing randomly.
    fallbacks = set()
    for k in range(30):
        fallbacks.add(generate_choices([('a',2),('b',1),('c',0),('d',0)])[3])
    unittest.assertEqual(fallbacks, {'c', 'd'})