'Expiration has no effect on the dummy cache'

def test_expiration(self):

    self.cache.set('expire1', 'very    quickly', 1)
    self.cache.set('expire2', 'very    quickly', 1)
    self.cache.set('expire3', 'very    quickly', 1)
    time.sleep(2)
    self.assertEqual(self.cache.get('expire1'), None)
    self.cache.add('expire2', 'newvalue')
    self.assertEqual(self.cache.get('expire2'), None)
    self.assertEqual(self.cache.has_key('expire3'), False)
