Refactored INSTALLED_APPS overrides.

* Introduced [un]set_installed_apps to handle changes to the
  INSTALLED_APPS setting.
* Refactored [un]set_available_apps to share its implementation
  with [un]set_installed_apps.
* Implemented a receiver to clear some app-related caches.
* Removed test_missing_app as it is basically impossible to reproduce
  this situation with public methods of the new app cache.

1 files changed, 0 insertions, 20 deletions

diff --git a/tests/app_loading/tests.py b/tests/app_loading/tests.py
index 0692597a5b..164e363161 100644
--- a/tests/app_loading/tests.py
+++ b/tests/app_loading/tests.py
@@ -3,11 +3,8 @@ from __future__ import unicode_literals
 import os
 import sys
 from unittest import TestCase
-import warnings
 
 from django.apps import app_cache
-from django.apps.cache import AppCache
-from django.test.utils import override_settings
 from django.utils._os import upath
 from django.utils import six
 
@@ -69,23 +66,6 @@ class EggLoadingTest(TestCase):
             with app_cache._with_app('broken_app'):
                 app_cache.get_app_config('omelet.app_no_models').models_module
 
-    def test_missing_app(self):
-        """
-        Test that repeated app loading doesn't succeed in case there is an
-        error. Refs #17667.
-        """
-        app_cache = AppCache()
-        # Pretend we're the master app cache to test the population process.
-        app_cache._apps_loaded = False
-        app_cache._models_loaded = False
-        with warnings.catch_warnings():
-            warnings.filterwarnings("ignore", "Overriding setting INSTALLED_APPS")
-            with override_settings(INSTALLED_APPS=['notexists']):
-                with self.assertRaises(ImportError):
-                    app_cache.get_model('notexists', 'nomodel')
-                with self.assertRaises(ImportError):
-                    app_cache.get_model('notexists', 'nomodel')
-
 
 class GetModelsTest(TestCase):
     def setUp(self):