Dropped AppCache._empty, _with_app and _without_app.

It's now easier to achieve the same effect with modify_settings or
override_settings.

8 files changed, 57 insertions, 140 deletions

diff --git a/django/apps/cache.py b/django/apps/cache.py
index bdd7e98e22..bd412f1192 100644
--- a/django/apps/cache.py
+++ b/django/apps/cache.py
@@ -1,7 +1,6 @@
 "Utilities for loading models and the modules that contain them."
 
 from collections import defaultdict, OrderedDict
-from contextlib import contextmanager
 import os
 import sys
 import warnings
@@ -350,61 +349,6 @@ class AppCache(object):
         """
         self.app_configs = self.stored_app_configs.pop()
 
-    ### DANGEROUS METHODS ### (only used to preserve existing tests)
-
-    def _begin_with_app(self, app_name):
-        # Returns an opaque value that can be passed to _end_with_app().
-        app_config = AppConfig.create(app_name)
-        if app_config.label in self.app_configs:
-            return None
-        else:
-            app_config.import_models(self.all_models[app_config.label])
-            self.app_configs[app_config.label] = app_config
-            return app_config
-
-    def _end_with_app(self, app_config):
-        if app_config is not None:
-            del self.app_configs[app_config.label]
-
-    @contextmanager
-    def _with_app(self, app_name):
-        app_config = self._begin_with_app(app_name)
-        try:
-            yield
-        finally:
-            self._end_with_app(app_config)
-
-    def _begin_without_app(self, app_name):
-        # Returns an opaque value that can be passed to _end_without_app().
-        return self.app_configs.pop(app_name.rpartition(".")[2], None)
-
-    def _end_without_app(self, app_config):
-        if app_config is not None:
-            self.app_configs[app_config.label] = app_config
-
-    @contextmanager
-    def _without_app(self, app_name):
-        app_config = self._begin_without_app(app_name)
-        try:
-            yield
-        finally:
-            self._end_without_app(app_config)
-
-    def _begin_empty(self):
-        app_configs, self.app_configs = self.app_configs, OrderedDict()
-        return app_configs
-
-    def _end_empty(self, app_configs):
-        self.app_configs = app_configs
-
-    @contextmanager
-    def _empty(self):
-        app_configs = self._begin_empty()
-        try:
-            yield
-        finally:
-            self._end_empty(app_configs)
-
     ### DEPRECATED METHODS GO BELOW THIS LINE ###
 
     def load_app(self, app_name):
diff --git a/django/contrib/contenttypes/tests.py b/django/contrib/contenttypes/tests.py
index 302cdbb5cf..ceac7ccd1b 100644
--- a/django/contrib/contenttypes/tests.py
+++ b/django/contrib/contenttypes/tests.py
@@ -1,6 +1,5 @@
 from __future__ import unicode_literals
 
-from django.apps import app_cache
 from django.contrib.contenttypes.models import ContentType
 from django.contrib.contenttypes.views import shortcut
 from django.contrib.sites.models import get_current_site
@@ -222,12 +221,12 @@ class ContentTypesTests(TestCase):
         user_ct = ContentType.objects.get_for_model(FooWithUrl)
         obj = FooWithUrl.objects.create(name="john")
 
-        with app_cache._with_app('django.contrib.sites'):
+        with self.modify_settings(INSTALLED_APPS={'append': 'django.contrib.sites'}):
             response = shortcut(request, user_ct.id, obj.id)
             self.assertEqual("http://%s/users/john/" % get_current_site(request).domain,
                              response._headers.get("location")[1])
 
-        with app_cache._without_app('django.contrib.sites'):
+        with self.modify_settings(INSTALLED_APPS={'remove': 'django.contrib.sites'}):
             response = shortcut(request, user_ct.id, obj.id)
             self.assertEqual("http://Example.com/users/john/",
                              response._headers.get("location")[1])
diff --git a/django/contrib/gis/tests/geoapp/test_feeds.py b/django/contrib/gis/tests/geoapp/test_feeds.py
index 638944db63..96ba26cece 100644
--- a/django/contrib/gis/tests/geoapp/test_feeds.py
+++ b/django/contrib/gis/tests/geoapp/test_feeds.py
@@ -3,17 +3,17 @@ from __future__ import unicode_literals
 from unittest import skipUnless
 from xml.dom import minidom
 
-from django.apps import app_cache
 from django.conf import settings
 from django.contrib.sites.models import Site
 from django.contrib.gis.geos import HAS_GEOS
 from django.contrib.gis.tests.utils import HAS_SPATIAL_DB
-from django.test import TestCase
+from django.test import TestCase, modify_settings
 
 if HAS_GEOS:
     from .models import City
 
 
+@modify_settings(INSTALLED_APPS={'append': 'django.contrib.sites'})
 @skipUnless(HAS_GEOS and HAS_SPATIAL_DB, "Geos and spatial db are required.")
 class GeoFeedTest(TestCase):
 
@@ -21,10 +21,6 @@ class GeoFeedTest(TestCase):
 
     def setUp(self):
         Site(id=settings.SITE_ID, domain="example.com", name="example.com").save()
-        self._with_sites = app_cache._begin_with_app('django.contrib.sites')
-
-    def tearDown(self):
-        app_cache._end_with_app(self._with_sites)
 
     def assertChildNodes(self, elem, expected):
         "Taken from syndication/tests.py."
diff --git a/django/contrib/gis/tests/geoapp/test_sitemaps.py b/django/contrib/gis/tests/geoapp/test_sitemaps.py
index 909a543bb6..c41cc53674 100644
--- a/django/contrib/gis/tests/geoapp/test_sitemaps.py
+++ b/django/contrib/gis/tests/geoapp/test_sitemaps.py
@@ -6,12 +6,11 @@ from xml.dom import minidom
 import os
 import zipfile
 
-from django.apps import app_cache
 from django.conf import settings
 from django.contrib.gis.geos import HAS_GEOS
 from django.contrib.gis.tests.utils import HAS_SPATIAL_DB
 from django.contrib.sites.models import Site
-from django.test import TestCase
+from django.test import TestCase, modify_settings
 from django.test.utils import IgnoreDeprecationWarningsMixin
 from django.utils._os import upath
 
@@ -19,6 +18,7 @@ if HAS_GEOS:
     from .models import City, Country
 
 
+@modify_settings(INSTALLED_APPS={'append': 'django.contrib.sites'})
 @skipUnless(HAS_GEOS and HAS_SPATIAL_DB, "Geos and spatial db are required.")
 class GeoSitemapTest(IgnoreDeprecationWarningsMixin, TestCase):
 
@@ -27,11 +27,6 @@ class GeoSitemapTest(IgnoreDeprecationWarningsMixin, TestCase):
     def setUp(self):
         super(GeoSitemapTest, self).setUp()
         Site(id=settings.SITE_ID, domain="example.com", name="example.com").save()
-        self._with_sites = app_cache._begin_with_app('django.contrib.sites')
-
-    def tearDown(self):
-        app_cache._end_with_app(self._with_sites)
-        super(GeoSitemapTest, self).tearDown()
 
     def assertChildNodes(self, elem, expected):
         "Taken from syndication/tests.py."
diff --git a/django/contrib/messages/tests/base.py b/django/contrib/messages/tests/base.py
index e03d229be3..e38749c13e 100644
--- a/django/contrib/messages/tests/base.py
+++ b/django/contrib/messages/tests/base.py
@@ -2,14 +2,14 @@ from unittest import skipUnless
 
 from django import http
 from django.apps import app_cache
-from django.conf import settings, global_settings
+from django.conf import global_settings
 from django.contrib.messages import constants, utils, get_level, set_level
 from django.contrib.messages.api import MessageFailure
 from django.contrib.messages.constants import DEFAULT_LEVELS
 from django.contrib.messages.storage import default_storage, base
 from django.contrib.messages.storage.base import Message
 from django.core.urlresolvers import reverse
-from django.test.utils import override_settings
+from django.test.utils import modify_settings, override_settings
 from django.utils.translation import ugettext_lazy
 
 
@@ -219,55 +219,48 @@ class BaseTests(object):
         for msg in data['messages']:
             self.assertContains(response, msg)
 
-    @override_settings(
-        MIDDLEWARE_CLASSES=filter(
-            lambda m: 'MessageMiddleware' not in m, settings.MIDDLEWARE_CLASSES),
-        TEMPLATE_CONTEXT_PROCESSORS=filter(
-            lambda p: 'context_processors.messages' not in p,
-            settings.TEMPLATE_CONTEXT_PROCESSORS),
-        MESSAGE_LEVEL=constants.DEBUG
+    @modify_settings(
+        INSTALLED_APPS={'remove': 'django.contrib.messages'},
+        MIDDLEWARE_CLASSES={'remove': 'django.contrib.messages.middleware.MessageMiddleware'},
+        TEMPLATE_CONTEXT_PROCESSORS={'remove': 'django.contrib.messages.context_processors.messages'},
     )
+    @override_settings(MESSAGE_LEVEL=constants.DEBUG)
     def test_middleware_disabled(self):
         """
         Tests that, when the middleware is disabled, an exception is raised
         when one attempts to store a message.
         """
-        with app_cache._without_app('django.contrib.messages'):
-            data = {
-                'messages': ['Test message %d' % x for x in range(5)],
-            }
-            reverse('django.contrib.messages.tests.urls.show')
-            for level in ('debug', 'info', 'success', 'warning', 'error'):
-                add_url = reverse('django.contrib.messages.tests.urls.add',
-                                  args=(level,))
-                self.assertRaises(MessageFailure, self.client.post, add_url,
-                                  data, follow=True)
+        data = {
+            'messages': ['Test message %d' % x for x in range(5)],
+        }
+        reverse('django.contrib.messages.tests.urls.show')
+        for level in ('debug', 'info', 'success', 'warning', 'error'):
+            add_url = reverse('django.contrib.messages.tests.urls.add',
+                              args=(level,))
+            self.assertRaises(MessageFailure, self.client.post, add_url,
+                              data, follow=True)
 
-    @override_settings(
-        MIDDLEWARE_CLASSES=filter(
-            lambda m: 'MessageMiddleware' not in m, settings.MIDDLEWARE_CLASSES),
-        TEMPLATE_CONTEXT_PROCESSORS=filter(
-            lambda p: 'context_processors.messages' not in p,
-            settings.TEMPLATE_CONTEXT_PROCESSORS),
-        MESSAGE_LEVEL=constants.DEBUG
+    @modify_settings(
+        INSTALLED_APPS={'remove': 'django.contrib.messages'},
+        MIDDLEWARE_CLASSES={'remove': 'django.contrib.messages.middleware.MessageMiddleware'},
+        TEMPLATE_CONTEXT_PROCESSORS={'remove': 'django.contrib.messages.context_processors.messages'},
     )
     def test_middleware_disabled_fail_silently(self):
         """
         Tests that, when the middleware is disabled, an exception is not
         raised if 'fail_silently' = True
         """
-        with app_cache._without_app('django.contrib.messages'):
-            data = {
-                'messages': ['Test message %d' % x for x in range(5)],
-                'fail_silently': True,
-            }
-            show_url = reverse('django.contrib.messages.tests.urls.show')
-            for level in ('debug', 'info', 'success', 'warning', 'error'):
-                add_url = reverse('django.contrib.messages.tests.urls.add',
-                                  args=(level,))
-                response = self.client.post(add_url, data, follow=True)
-                self.assertRedirects(response, show_url)
-                self.assertFalse('messages' in response.context)
+        data = {
+            'messages': ['Test message %d' % x for x in range(5)],
+            'fail_silently': True,
+        }
+        show_url = reverse('django.contrib.messages.tests.urls.show')
+        for level in ('debug', 'info', 'success', 'warning', 'error'):
+            add_url = reverse('django.contrib.messages.tests.urls.add',
+                              args=(level,))
+            response = self.client.post(add_url, data, follow=True)
+            self.assertRedirects(response, show_url)
+            self.assertFalse('messages' in response.context)
 
     def stored_messages_count(self, storage, response):
         """
diff --git a/django/contrib/redirects/tests.py b/django/contrib/redirects/tests.py
index 0784a6a6f3..99c5c3fd38 100644
--- a/django/contrib/redirects/tests.py
+++ b/django/contrib/redirects/tests.py
@@ -1,22 +1,18 @@
 from django import http
-from django.apps import app_cache
 from django.conf import settings
 from django.contrib.sites.models import Site
 from django.core.exceptions import ImproperlyConfigured
 from django.test import TestCase
-from django.test.utils import override_settings
+from django.test.utils import modify_settings, override_settings
 from django.utils import six
 
 from .middleware import RedirectFallbackMiddleware
 from .models import Redirect
 
 
-@override_settings(
-    APPEND_SLASH=False,
-    MIDDLEWARE_CLASSES=list(settings.MIDDLEWARE_CLASSES) +
-    ['django.contrib.redirects.middleware.RedirectFallbackMiddleware'],
-    SITE_ID=1,
-)
+@modify_settings(MIDDLEWARE_CLASSES={'append':
+    'django.contrib.redirects.middleware.RedirectFallbackMiddleware'})
+@override_settings(APPEND_SLASH=False, SITE_ID=1)
 class RedirectTests(TestCase):
 
     def setUp(self):
@@ -57,10 +53,10 @@ class RedirectTests(TestCase):
         response = self.client.get('/initial')
         self.assertEqual(response.status_code, 410)
 
+    @modify_settings(INSTALLED_APPS={'remove': 'django.contrib.sites'})
     def test_sites_not_installed(self):
-        with app_cache._without_app('django.contrib.sites'):
-            with self.assertRaises(ImproperlyConfigured):
-                RedirectFallbackMiddleware()
+        with self.assertRaises(ImproperlyConfigured):
+            RedirectFallbackMiddleware()
 
 
 class OverriddenRedirectFallbackMiddleware(RedirectFallbackMiddleware):
@@ -69,11 +65,9 @@ class OverriddenRedirectFallbackMiddleware(RedirectFallbackMiddleware):
     response_redirect_class = http.HttpResponseRedirect
 
 
-@override_settings(
-    MIDDLEWARE_CLASSES=list(settings.MIDDLEWARE_CLASSES) +
-    ['django.contrib.redirects.tests.OverriddenRedirectFallbackMiddleware'],
-    SITE_ID=1,
-)
+@modify_settings(MIDDLEWARE_CLASSES={'append':
+    'django.contrib.redirects.tests.OverriddenRedirectFallbackMiddleware'})
+@override_settings(SITE_ID=1)
 class OverriddenRedirectMiddlewareTests(TestCase):
 
     def setUp(self):
diff --git a/django/contrib/sitemaps/tests/test_http.py b/django/contrib/sitemaps/tests/test_http.py
index fca644538b..583b0b44bf 100644
--- a/django/contrib/sitemaps/tests/test_http.py
+++ b/django/contrib/sitemaps/tests/test_http.py
@@ -9,7 +9,7 @@ from django.conf import settings
 from django.contrib.sitemaps import Sitemap, GenericSitemap
 from django.contrib.sites.models import Site
 from django.core.exceptions import ImproperlyConfigured
-from django.test.utils import override_settings
+from django.test import modify_settings, override_settings
 from django.utils.formats import localize
 from django.utils._os import upath
 from django.utils.translation import activate, deactivate
@@ -106,17 +106,17 @@ class HTTPSitemapTests(SitemapTestsBase):
         self.assertContains(response, '<lastmod>%s</lastmod>' % date.today())
         deactivate()
 
+    @modify_settings(INSTALLED_APPS={'remove': 'django.contrib.sites'})
     def test_requestsite_sitemap(self):
         # Make sure hitting the flatpages sitemap without the sites framework
         # installed doesn't raise an exception.
-        with app_cache._without_app('django.contrib.sites'):
-            response = self.client.get('/simple/sitemap.xml')
-            expected_content = """<?xml version="1.0" encoding="UTF-8"?>
+        response = self.client.get('/simple/sitemap.xml')
+        expected_content = """<?xml version="1.0" encoding="UTF-8"?>
 <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
 <url><loc>http://testserver/location/</loc><lastmod>%s</lastmod><changefreq>never</changefreq><priority>0.5</priority></url>
 </urlset>
 """ % date.today()
-            self.assertXMLEqual(response.content.decode('utf-8'), expected_content)
+        self.assertXMLEqual(response.content.decode('utf-8'), expected_content)
 
     @skipUnless(app_cache.has_app('django.contrib.sites'),
                 "django.contrib.sites app not installed.")
@@ -128,14 +128,14 @@ class HTTPSitemapTests(SitemapTestsBase):
         Site.objects.all().delete()
         self.assertRaises(ImproperlyConfigured, Sitemap().get_urls)
 
+    @modify_settings(INSTALLED_APPS={'remove': 'django.contrib.sites'})
     def test_sitemap_get_urls_no_site_2(self):
         """
         Check we get ImproperlyConfigured when we don't pass a site object to
         Sitemap.get_urls if Site objects exists, but the sites framework is not
         actually installed.
         """
-        with app_cache._without_app('django.contrib.sites'):
-            self.assertRaises(ImproperlyConfigured, Sitemap().get_urls)
+        self.assertRaises(ImproperlyConfigured, Sitemap().get_urls)
 
     def test_sitemap_item(self):
         """
diff --git a/django/contrib/sites/tests.py b/django/contrib/sites/tests.py
index 79bcae9aa6..fee1189c97 100644
--- a/django/contrib/sites/tests.py
+++ b/django/contrib/sites/tests.py
@@ -1,22 +1,18 @@
 from __future__ import unicode_literals
 
-from django.apps import app_cache
 from django.conf import settings
 from django.contrib.sites.models import Site, RequestSite, get_current_site
 from django.core.exceptions import ObjectDoesNotExist, ValidationError
 from django.http import HttpRequest
 from django.test import TestCase
-from django.test.utils import override_settings
+from django.test.utils import modify_settings, override_settings
 
 
+@modify_settings(INSTALLED_APPS={'append': 'django.contrib.sites'})
 class SitesFrameworkTests(TestCase):
 
     def setUp(self):
         Site(id=settings.SITE_ID, domain="example.com", name="example.com").save()
-        self._with_sites = app_cache._begin_with_app('django.contrib.sites')
-
-    def tearDown(self):
-        app_cache._end_with_app(self._with_sites)
 
     def test_save_another(self):
         # Regression for #17415
@@ -67,7 +63,7 @@ class SitesFrameworkTests(TestCase):
         self.assertRaises(ObjectDoesNotExist, get_current_site, request)
 
         # A RequestSite is returned if the sites framework is not installed
-        with app_cache._without_app('django.contrib.sites'):
+        with self.modify_settings(INSTALLED_APPS={'remove': 'django.contrib.sites'}):
             site = get_current_site(request)
             self.assertTrue(isinstance(site, RequestSite))
             self.assertEqual(site.name, "example.com")