Commit b161c01c authored by Aymeric Augustin's avatar Aymeric Augustin
Browse files

Fixed #22920 -- Avoid masking some exceptions. 

If loading an application trigger an ImportError, the details of that
error were lost in some cases. Thanks Ben Davis for the report.
parent d3543af7

django/apps/config.py

+12 −7
Original line number Diff line number Diff line
@@ -87,6 +87,10 @@ class AppConfig(object): 
            module = import_module(entry)



        except ImportError:

            # Track that importing as an app module failed. If importing as an

            # app config class fails too, we'll trigger the ImportError again.

            module = None



            mod_path, _, cls_name = entry.rpartition('.')



            # Raise the original exception when entry cannot be a path to an
@@ -104,8 +108,8 @@ class AppConfig(object): 
            else:

                mod_path, _, cls_name = entry.rpartition('.')



        # If we're reaching this point, we must load the app config class

        # located at <mod_path>.<cls_name>.

        # If we're reaching this point, we must attempt to load the app config

        # class located at <mod_path>.<cls_name>



        # Avoid django.utils.module_loading.import_by_path because it

        # masks errors -- it reraises ImportError as ImproperlyConfigured.
@@ -113,11 +117,12 @@ class AppConfig(object): 
        try:

            cls = getattr(mod, cls_name)

        except AttributeError:

            # Emulate the error that "from <mod_path> import <cls_name>"

            # would raise when <mod_path> exists but not <cls_name>, with

            # more context (Python just says "cannot import name ...").

            raise ImportError(

                "cannot import name '%s' from '%s'" % (cls_name, mod_path))

            if module is None:

                # If importing as an app module failed, that error probably

                # contains the most informative traceback. Trigger it again.

                import_module(entry)

            else:

                raise



        # Check for obvious errors. (This check prevents duck typing, but

        # it could be removed if it became a problem in practice.)

tests/apps/failing_app/__init__.py

0 → 100644
+1 −0
Original line number Diff line number Diff line 
raise ImportError("Oops")

tests/apps/tests.py

+8 −0
Original line number Diff line number Diff line
@@ -166,6 +166,14 @@ class AppsTests(TestCase): 
            with self.settings(INSTALLED_APPS=['apps.apps.RelabeledAppsConfig', 'apps']):

                pass



    def test_import_exception_is_not_masked(self):

        """

        App discovery should preserve stack traces. Regression test for #22920.

        """

        with six.assertRaisesRegex(self, ImportError, "Oops"):

            with self.settings(INSTALLED_APPS=['apps.failing_app']):

                pass



    def test_models_py(self):

        """

        Tests that the models in the models.py file were loaded correctly.