Fixed #19203 -- Added isolation to a humanize test

# systems may support all possibilities). When USE_TZ is True, this is

# interpreted as the default user time zone.

TIME_ZONE = 'America/Chicago'

TIME_ZONE = 'Europe/Paris'

# If you set this to True, Django will use timezone-aware datetimes.

USE_TZ = False

from __future__ import unicode_literals

import datetime

try:

    import pytz

except ImportError:

    pytz = None

from django.conf import settings

from django.contrib.humanize.templatetags import humanize

from django.template import Template, Context, defaultfilters

from django.test import TestCase

from django.utils import translation

from django.utils.translation import ugettext as _

from django.utils import tzinfo

from django.utils.unittest import skipIf

# Mock out datetime in some tests so they don't fail occasionally when they

        # As 24h of difference they will never be the same

        self.assertNotEqual(naturalday_one, naturalday_two)

    @skipIf(settings.TIME_ZONE != "Ameria/Chicago" and pytz is None,

            "this test requires pytz when a non-default time zone is set")

    def test_naturalday_uses_localtime(self):

        # Regression for #18504

        # This is 2012-03-08HT19:30:00-06:00 in Ameria/Chicago

        orig_humanize_datetime, humanize.datetime = humanize.datetime, MockDateTime

        try:

            with override_settings(USE_TZ=True):

            with override_settings(TIME_ZONE="America/Chicago", USE_TZ=True):

                self.humanize_tester([dt], ['yesterday'], 'naturalday')

        finally:

            humanize.datetime = orig_humanize_datetime