Method test_hash_distribution

Lib/test/test_hash.py:342–356

(self)

class HashDistributionTestCase(unittest.TestCase):

    def test_hash_distribution(self):
        # check for hash collision
        base = "abcdefghabcdefg"
        for i in range(1, len(base)):
            prefix = base[:i]
            with self.subTest(prefix=prefix):
                s15 = set()
                s255 = set()
                for c in range(256):
                    h = hash(prefix + chr(c))
                    s15.add(h & 0xf)
                    s255.add(h & 0xff)
                # SipHash24 distribution depends on key, usually > 60%
                self.assertGreater(len(s15), 8, prefix)
                self.assertGreater(len(s255), 128, prefix)

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