interval.py

import unittest

def is_interval(interval, **kwargs):
    to_list = lambda value: [value] if isinstance(value, basestring) else value
    list_from_kwarg = lambda key: to_list(kwargs.get(key, []))
    units = ['y', 'm', 'd', 'h', 'i', 's']
    only = list_from_kwarg('only')
    if only:
        return is_interval(interval, with_ = only, without = list(set(units) - set(only)))
    with_ = list_from_kwarg('with_')
    without = list_from_kwarg('without')
    return all([interval.get(unit) > 0 for unit in with_]) and all([interval.get(unit) == 0 for unit in without])

class TestIsInterval(unittest.TestCase):
    def interval(self, **kwargs):
        zeroes = {'y': 0, 'm': 0, 'd': 0, 'h': 0, 'i': 0, 's': 0}
        zeroes.update(kwargs)
        return zeroes

    def testOnlyTrueWithSingleSeconds(self):
        self.assertTrue(is_interval(self.interval(s=5), only = ['s']));

    def testOnlyFalseWithAllZeroesInterval(self):
        self.assertFalse(is_interval(self.interval(), only = ['s']));

    def testOnlyFalseWithSecondAndHours(self):
        self.assertFalse(is_interval(self.interval(s=5, h=10), only = ['s']));

    def testWithSecondsAndAlsoHours(self):
        self.assertTrue(is_interval(self.interval(s=5, h=10), with_ = ['s']))

    def testOnlyString(self):
        self.assertTrue(is_interval(self.interval(s=5), only = 's'))

if __name__ == '__main__':
    unittest.main()