[1.6.x] Factorized requires_tz_support decorator in test utils

Thanks Aymeric Augustin for the suggestion. Refs #21165.
Backport of c1c44b2506 from master.

django/test/utils.py

@@ -2,6 +2,7 @@ from contextlib import contextmanager
 import logging
 import re
 import sys
+import time
 import warnings
 from functools import wraps
 from xml.dom.minidom import parseString, Node
@@ -17,14 +18,16 @@ from django.test.signals import template_rendered, setting_changed
 from django.utils.encoding import force_str
 from django.utils import six
 from django.utils.translation import deactivate
+from django.utils.unittest import skipUnless
 
 
 __all__ = (
     'Approximate', 'ContextList',  'get_runner', 'override_settings',
-    'setup_test_environment', 'teardown_test_environment',
+    'requires_tz_support', 'setup_test_environment', 'teardown_test_environment',
 )
 
 RESTORE_LOADERS_ATTR = '_original_template_source_loaders'
+TZ_SUPPORT = hasattr(time, 'tzset')
 
 
 class Approximate(object):
@@ -436,3 +439,13 @@ def patch_logger(logger_name, log_level):
         yield calls
     finally:
         setattr(logger, log_level, orig)
+
+
+# On OSes that don't provide tzset (Windows), we can't set the timezone
+# in which the program runs. As a consequence, we must skip tests that
+# don't enforce a specific timezone (with timezone.override or equivalent),
+# or attempt to interpret naive datetimes in the default timezone.
+
+requires_tz_support = skipUnless(TZ_SUPPORT,
+        "This test relies on the ability to run a program in an arbitrary "
+        "time zone, but your operating system isn't able to do that.")

tests/generic_views/test_dates.py

@@ -1,27 +1,14 @@
 from __future__ import absolute_import
 
-import time
 import datetime
 
 from django.core.exceptions import ImproperlyConfigured
 from django.test import TestCase, skipUnlessDBFeature
-from django.test.utils import override_settings
+from django.test.utils import override_settings, requires_tz_support
 from django.utils import timezone
-from django.utils.unittest import skipUnless
 
 from .models import Book, BookSigning
 
-TZ_SUPPORT = hasattr(time, 'tzset')
-
-# On OSes that don't provide tzset (Windows), we can't set the timezone
-# in which the program runs. As a consequence, we must skip tests that
-# don't enforce a specific timezone (with timezone.override or equivalent),
-# or attempt to interpret naive datetimes in the default timezone.
-
-requires_tz_support = skipUnless(TZ_SUPPORT,
-        "This test relies on the ability to run a program in an arbitrary "
-        "time zone, but your operating system isn't able to do that.")
-
 
 def _make_books(n, base_date):
     for i in range(n):

tests/timezones/tests.py

@@ -4,7 +4,6 @@ import datetime
 import os
 import re
 import sys
-import time
 import warnings
 from xml.dom.minidom import parseString
 
@@ -21,11 +20,11 @@ from django.db.models import Min, Max
 from django.http import HttpRequest
 from django.template import Context, RequestContext, Template, TemplateSyntaxError
 from django.test import TestCase, skipIfDBFeature, skipUnlessDBFeature
-from django.test.utils import override_settings
+from django.test.utils import override_settings, requires_tz_support
 from django.utils import six
 from django.utils import timezone
 from django.utils.tzinfo import FixedOffset
-from django.utils.unittest import skipIf, skipUnless
+from django.utils.unittest import skipIf
 
 from .forms import EventForm, EventSplitForm, EventLocalizedForm, EventModelForm, EventLocalizedModelForm
 from .models import Event, MaybeEvent, Session, SessionEvent, Timestamp, AllDayEvent
@@ -43,17 +42,6 @@ UTC = timezone.utc
 EAT = FixedOffset(180)      # Africa/Nairobi
 ICT = FixedOffset(420)      # Asia/Bangkok
 
-TZ_SUPPORT = hasattr(time, 'tzset')
-
-# On OSes that don't provide tzset (Windows), we can't set the timezone
-# in which the program runs. As a consequence, we must skip tests that
-# don't enforce a specific timezone (with timezone.override or equivalent),
-# or attempt to interpret naive datetimes in the default timezone.
-
-requires_tz_support = skipUnless(TZ_SUPPORT,
-        "This test relies on the ability to run a program in an arbitrary "
-        "time zone, but your operating system isn't able to do that.")
-
 
 @override_settings(TIME_ZONE='Africa/Nairobi', USE_TZ=False)
 class LegacyDatabaseTests(TestCase):