'Expiration has no effect on the dummy cache'

def test_expiration(self):

    cache.set('expire1', 'very    quickly', 1)
    cache.set('expire2', 'very    quickly', 1)
    cache.set('expire3', 'very    quickly', 1)
    time.sleep(2)
    self.assertIsNone(cache.get('expire1'))
    cache.add('expire2', 'newvalue')
    self.assertIsNone(cache.get('expire2'))
    self.assertFalse(cache.has_key('expire3'))
