Fixed #23670 -- Prevented partial import state during module autodiscovery

Thanks kostko for the report.

django/utils/module_loading.py

@@ -64,23 +64,23 @@ def autodiscover_modules(*args, **kwargs):
 
     register_to = kwargs.get('register_to')
     for app_config in apps.get_app_configs():
+        for module_to_search in args:
             # Attempt to import the app's module.
             try:
                 if register_to:
                     before_import_registry = copy.copy(register_to._registry)
 
-            for module_to_search in args:
                 import_module('%s.%s' % (app_config.name, module_to_search))
             except:
-            # Reset the model registry to the state before the last import as
+                # Reset the registry to the state before the last import
-            # this import will have to reoccur on the next request and this
+                # as this import will have to reoccur on the next request and
-            # could raise NotRegistered and AlreadyRegistered exceptions
+                # this could raise NotRegistered and AlreadyRegistered
-            # (see #8245).
+                # exceptions (see #8245).
                 if register_to:
                     register_to._registry = before_import_registry
 
                 # Decide whether to bubble up this error. If the app just
-            # doesn't have an admin module, we can ignore the error
+                # doesn't have the module in question, we can ignore the error
                 # attempting to import it, otherwise we want it to bubble up.
                 if module_has_submodule(app_config.module, module_to_search):
                     raise

tests/utils_tests/test_module/another_good_module.py

@@ -1 +1,6 @@
+from . import site
 content = 'Another Good Module'
+
+site._registry.update({
+    'lorem': 'ipsum',
+})

tests/utils_tests/test_module_loading.py

@@ -155,6 +155,15 @@ class ModuleImportTestCase(IgnoreDeprecationWarningsMixin, unittest.TestCase):
 @modify_settings(INSTALLED_APPS={'append': 'utils_tests.test_module'})
 class AutodiscoverModulesTestCase(SimpleTestCase):
 
+    def tearDown(self):
+        sys.path_importer_cache.clear()
+
+        sys.modules.pop('utils_tests.test_module.another_bad_module', None)
+        sys.modules.pop('utils_tests.test_module.another_good_module', None)
+        sys.modules.pop('utils_tests.test_module.bad_module', None)
+        sys.modules.pop('utils_tests.test_module.good_module', None)
+        sys.modules.pop('utils_tests.test_module', None)
+
     def test_autodiscover_modules_found(self):
         autodiscover_modules('good_module')
 
@@ -172,12 +181,28 @@ class AutodiscoverModulesTestCase(SimpleTestCase):
     def test_autodiscover_modules_several_found(self):
         autodiscover_modules('good_module', 'another_good_module')
 
+    def test_autodiscover_modules_several_found_with_registry(self):
+        from .test_module import site
+        autodiscover_modules('good_module', 'another_good_module', register_to=site)
+        self.assertEqual(site._registry, {'lorem': 'ipsum'})
+
     def test_validate_registry_keeps_intact(self):
         from .test_module import site
         with six.assertRaisesRegex(self, Exception, "Some random exception."):
             autodiscover_modules('another_bad_module', register_to=site)
         self.assertEqual(site._registry, {})
 
+    def test_validate_registry_resets_after_erroneous_module(self):
+        from .test_module import site
+        with six.assertRaisesRegex(self, Exception, "Some random exception."):
+            autodiscover_modules('another_good_module', 'another_bad_module', register_to=site)
+        self.assertEqual(site._registry, {'lorem': 'ipsum'})
+
+    def test_validate_registry_resets_after_missing_module(self):
+        from .test_module import site
+        autodiscover_modules('does_not_exist', 'another_good_module', 'does_not_exist2', register_to=site)
+        self.assertEqual(site._registry, {'lorem': 'ipsum'})
+
 
 class ProxyFinder(object):
     def __init__(self):