Millisecond off in retrieved datetime in https://github.com/datastax/python-driver/commit/e9c55a1ad951f61a4d306eadc6235e3b220b598a

py.test compare output

>           assert orig == ret
E           assert TimedTask(tid..., 13, 665000)) == TimedTask(tid=..., 13, 664999))
E             Full diff:
E             - TimedTask(tid=UUID('6...27'), created=datetime.datetime(2016, 2, 25, 14, 32, 13, 665000))
E             ?                                                                                                                  ^^^^
E             + TimedTask(tid=UUID('6...27'), created=datetime.datetime(2016, 2, 25, 14, 32, 13, 664999))
E             ?                                                                                                                  ^^^^

Note, the time saved was already rounded to milliseconds. The time returned is one ms less than the saved time.

test_retrieved_time.py

# -*- coding: utf-8 -*-

import uuid
from datetime import datetime

from cassandra.cqlengine import columns
from cassandra.cqlengine import connection
from cassandra.cqlengine.management import (
    create_keyspace_simple, drop_keyspace, sync_table
)
from cassandra.cqlengine.models import Model

from sirmodels.settings import CASSANDRA_HOSTS
from sirmodels.settings import CASSANDRA_KEYSPACE


class TimedTask(Model):
    tid = columns.UUID(primary_key=True, required=True)
    created = columns.DateTime()


def reset_keyspace():
    connection.setup(CASSANDRA_HOSTS, CASSANDRA_KEYSPACE,
                     protocol_version=3)
    drop_keyspace(CASSANDRA_KEYSPACE)
    create_keyspace_simple(CASSANDRA_KEYSPACE, 1)


def round_now():
    """
    return a now with ms granularity
    """
    now = datetime.now()
    microsecond = now.microsecond
    microsecond = microsecond / 1000 * 1000
    return datetime.now().replace(microsecond=microsecond)


def test_timed_task():
    reset_keyspace()
    model = TimedTask
    sync_table(model)
    for i in range(1000):
        print i
        now = round_now()
        tid = uuid.uuid4()
        orig = model.create(tid=tid, created=now)
        ret = model.objects.get(tid=tid)
        assert orig == ret
    print '1000 ok'
    assert 0

Caused by commit: datastax/python-driver@a98078b ??