def test_hash(self, size):
        # Not sure if we can do any meaningful tests here...  Even if we
        # start relying on the exact algorithm used, the result will be
        # different depending on the size of the C 'long int'.  Even this
        # test is dodgy (there's no *guarantee* that the two things should
        # have a different hash, even if they, in the current
        # implementation, almost always do.)
        s = '\x00' * size
        h1 = hash(s)
        del s
        s = '\x00' * (size + 1)
        self.failIf(h1 == hash(s))