Moved list of models inside AppConfig instances.

This commit is a refactoring with no change of functionality, according
to the following invariants:

- An app_label that was in app_configs and app_models stays in
  app_config and has its 'installed' attribute set to True.

- An app_label that was in app_models but not in app_configs is added to
  app_configs and has its 'installed' attribute set to True.

As a consequence, all the code that iterated on app_configs is modified
to check for the 'installed' attribute. Code that iterated on app_models
is rewritten in terms of app_configs.

Many tests that stored and restored the state of the app cache were
updated.

In the long term, we should reconsider the usefulness of allowing
importing models from non-installed applications. This doesn't sound
particularly useful, can be a trap in some circumstances, and causes
significant complexity in sensitive areas of Django.

1 files changed, 0 insertions, 2 deletions

diff --git a/tests/proxy_model_inheritance/tests.py b/tests/proxy_model_inheritance/tests.py
index f3cdba20a9..4c6e8c433e 100644
--- a/tests/proxy_model_inheritance/tests.py
+++ b/tests/proxy_model_inheritance/tests.py
@@ -34,8 +34,6 @@ class ProxyModelInheritanceTests(TransactionTestCase):
         sys.path = self.old_sys_path
         del app_cache.app_configs['app1']
         del app_cache.app_configs['app2']
-        del app_cache.app_models['app1']
-        del app_cache.app_models['app2']
 
     def test_table_exists(self):
         try: