Added TestCase.settings context manager to easily override settings in test methods.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16165 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/test/testcases.py

@@ -2,11 +2,12 @@ from __future__ import with_statement
 
 import re
 import sys
+from contextlib import contextmanager
 from functools import wraps
 from urlparse import urlsplit, urlunsplit
 from xml.dom.minidom import parseString, Node
 
-from django.conf import settings
+from django.conf import settings, UserSettingsHolder
 from django.core import mail
 from django.core.management import call_command
 from django.core.signals import request_started
@@ -341,6 +342,22 @@ class TransactionTestCase(ut2.TestCase):
         """
         restore_warnings_state(self._warnings_state)
 
+    @contextmanager
+    def settings(self, **options):
+        """
+        A context manager that temporarily sets a setting and reverts
+        back to the original value when exiting the context.
+        """
+        old_wrapped = settings._wrapped
+        override = UserSettingsHolder(settings._wrapped)
+        try:
+            for key, new_value in options.items():
+                setattr(override, key, new_value)
+            settings._wrapped = override
+            yield
+        finally:
+            settings._wrapped = old_wrapped
+
     def assertRedirects(self, response, expected_url, status_code=302,
                         target_status_code=200, host=None, msg_prefix=''):
         """Asserts that a response redirected to a specific URL, and that the