Respect System Timezone

[bryanhelmig]

This fails a ton of built in tests - not sure anyway wants to use it or do the work to make tests pass.

It works for us though - we're forking it internally - thought maybe someone else could find it useful? We're using Django which patches the system TZ. Googlers - I hope you find out why your freezegun is working incorrectly or showing the wrong time with Django!

Here is an example of a test that worked for us:

import pytz
import time
from datetime import datetime, date

from django.test import TestCase

from freezegun import freeze_time


class FreezeTimeOverrideTest(TestCase):
    def test_now_with_utc_dance(self):
        now = datetime.now()

        time_time = int(time.time())
        time_localtime = time.localtime()
        time_gmtime = time.gmtime()
        date_today = date.today()
        datetime_now = now.replace(microsecond=0)
        datetime_now_pytz_UTC = datetime.now(pytz.UTC).replace(microsecond=0)
        datetime_utcnow = datetime.utcnow().replace(microsecond=0)
        datetime_now_pytz_timezone_America_Los_Angeles = datetime.now(pytz.timezone('America/Los_Angeles')).replace(microsecond=0)

        time.sleep(1.2)
        # CST from django system override
        freeze_now = now.replace(microsecond=0).isoformat()
        del now

        with freeze_time(freeze_now):
            self.assertEquals(
                int(time.time()),
                time_time
            )
            self.assertEquals(
                list(time.localtime())[:-1], # isdst is wrong...
                list(time_localtime)[:-1] # isdst is wrong...
            )
            self.assertEquals(
                list(time.gmtime())[:-1], # isdst is wrong...
                list(time_gmtime)[:-1] # isdst is wrong...
            )
            self.assertEquals(
                date.today(),
                date_today
            )
            self.assertEquals(
                datetime.now().replace(microsecond=0),
                datetime_now
            )
            self.assertEquals(
                datetime.now(pytz.UTC).replace(microsecond=0),
                datetime_now_pytz_UTC
            )
            self.assertEquals(
                datetime.utcnow().replace(microsecond=0),
                datetime_utcnow
            )
            self.assertEquals(
                datetime.now(pytz.timezone('America/Los_Angeles')).replace(microsecond=0),
                datetime_now_pytz_timezone_America_Los_Angeles
            )

[bryanhelmig]

isdst is currently wrong too - haven't figured that one out. The "fix" is really inelegant as well. :shrugs:

Mainly putting it out there just in case someone else hits the same thing.

[WhyNotHugo]

Any updated on this? We're seeing some breakage downstream because of this issue.

[spulec]

No update from me. Would be open to someone taking this and running with it.

[boxed]

Am I reading this PR correctly in that it wants to make tests with frozen time not freeze to a predictable time but to whatever local time zone is on the system?

If that's the case then it seems pretty obvious to me why this would fail all the tests: it's backwards incompatible and would result in flaky tests if freezegun would to have these changes.