Method test_uuid6_uniqueness

Lib/test/test_uuid.py:767–795

(self)

            equal(u.fields[5], fake_node_value)

    def test_uuid6_uniqueness(self):
        # Test that UUIDv6-generated values are unique.

        # Unlike UUIDv8, only 62 bits can be randomized for UUIDv6.
        # In practice, however, it remains unlikely to generate two
        # identical UUIDs for the same 60-bit timestamp if neither
        # the node ID nor the clock sequence is specified.
        uuids = {self.uuid.uuid6() for _ in range(1000)}
        self.assertEqual(len(uuids), 1000)
        versions = {u.version for u in uuids}
        self.assertSetEqual(versions, {6})

        timestamp = 0x1ec9414c_232a_b00
        fake_nanoseconds = (timestamp - 0x1b21dd21_3814_000) * 100

        with mock.patch('time.time_ns', return_value=fake_nanoseconds):
            def gen():
                with mock.patch.object(self.uuid, '_last_timestamp_v6', None):
                    return self.uuid.uuid6(node=0, clock_seq=None)

            # By the birthday paradox, sampling N = 1024 UUIDs with identical
            # node IDs and timestamps results in duplicates with probability
            # close to 1 (not having a duplicate happens with probability of
            # order 1E-15) since only the 14-bit clock sequence is randomized.
            N = 1024
            uuids = {gen() for _ in range(N)}
            self.assertSetEqual({u.node for u in uuids}, {0})
            self.assertSetEqual({u.time for u in uuids}, {timestamp})
            self.assertLess(len(uuids), N, 'collision property does not hold')

    def test_uuid6_node(self):
        # Make sure the given node ID appears in the UUID.