Ticket #17667: 17667.diff

django/db/models/loading.py

@@ -81 +81 @@
         Loads the app with the provided fully qualified name, and returns the
         model module.
         """
+        app_module = import_module(app_name)
         self.handled[app_name] = None
         self.nesting_level += 1
-        app_module = import_module(app_name)
         try:
             models = import_module('.models', app_name)
         except ImportError:

tests/regressiontests/app_loading/tests.py

@@ -6 +6 @@
 import time
 
 from django.conf import Settings
-from django.db.models.loading import cache, load_app, get_model, get_models
+from django.db.models.loading import cache, load_app, get_model, get_models, AppCache
+from django.test.utils import override_settings
 from django.utils.unittest import TestCase
 
 class EggLoadingTest(TestCase):
@@ -59 +60 @@
         egg_name = '%s/brokenapp.egg' % self.egg_dir
         sys.path.append(egg_name)
         self.assertRaises(ImportError, load_app, 'broken_app')
+        raised = None
         try:
             load_app('broken_app')
         except ImportError, e:
-            # Make sure the message is indicating the actual
-            # problem in the broken app.
-            self.assertTrue("modelz" in e.args[0])
+            raised = e
+        # Make sure the message is indicating the actual
+        # problem in the broken app.
+        self.assertTrue(raised is not None)
+        self.assertTrue("modelz" in raised.args[0])
+    
+    def test_missing_app(self):
+        """
+        Test that repeated app loading doesn't succeed in case there is an
+        error. Refs #17667.
+        """
+        try:
+            # AppCache is a Borg, so we can instantiate one and change its loaded to False
+            # to force the following code to actually try to populate the cache.
+            a = AppCache()
+            a.loaded = False
+            with override_settings(INSTALLED_APPS=('notexists',)):
+                self.assertRaises(ImportError, get_model, 'notexists', 'nomodel', seed_cache=True)
+                self.assertRaises(ImportError, get_model, 'notexists', 'nomodel', seed_cache=True)
+        finally:
+            a.loaded = True
 
 
 class GetModelsTest(TestCase):