Fixed #31870 -- Fixed crash when populating app registry with empty or without apps module.

Regression in 3f2821af6bc48fa8e7970c1ce27bc54c3172545e.

1 files changed, 52 insertions, 0 deletions

diff --git a/tests/apps/tests.py b/tests/apps/tests.py
index f4b0a8879b..cf487a65da 100644
--- a/tests/apps/tests.py
+++ b/tests/apps/tests.py
@@ -10,9 +10,13 @@ from django.test.utils import extend_sys_path, isolate_apps
 from django.utils.deprecation import RemovedInDjango41Warning
 
 from .explicit_default_config_app.apps import ExplicitDefaultConfig
+from .explicit_default_config_empty_apps import ExplicitDefaultConfigEmptyApps
 from .explicit_default_config_mismatch_app.not_apps import (
     ExplicitDefaultConfigMismatch,
 )
+from .explicit_default_config_without_apps import (
+    ExplicitDefaultConfigWithoutApps,
+)
 from .models import SoAlternative, TotallyNormal, new_apps
 from .one_config_app.apps import OneConfig
 from .two_configs_one_default_app.apps import TwoConfig
@@ -520,3 +524,51 @@ class DeprecationTests(SimpleTestCase):
             with self.settings(INSTALLED_APPS=['apps.explicit_default_config_mismatch_app']):
                 config = apps.get_app_config('explicit_default_config_mismatch_app')
             self.assertIsInstance(config, ExplicitDefaultConfigMismatch)
+
+    def test_explicit_default_app_config_empty_apps(self):
+        """
+        Load an app that specifies a default AppConfig class in __init__ and
+        have an empty apps module.
+        """
+        msg = (
+            "'apps.explicit_default_config_empty_apps' defines "
+            "default_app_config = 'apps.explicit_default_config_empty_apps."
+            "ExplicitDefaultConfigEmptyApps'. However, Django's automatic "
+            "detection did not find this configuration. You should move the "
+            "default config class to the apps submodule of your application "
+            "and, if this module defines several config classes, mark the "
+            "default one with default = True."
+        )
+        with self.assertRaisesMessage(RemovedInDjango41Warning, msg):
+            with self.settings(INSTALLED_APPS=['apps.explicit_default_config_empty_apps']):
+                pass
+        with ignore_warnings(category=RemovedInDjango41Warning):
+            with self.settings(INSTALLED_APPS=['apps.explicit_default_config_empty_apps']):
+                self.assertIsInstance(
+                    apps.get_app_config('explicit_default_config_empty_apps'),
+                    ExplicitDefaultConfigEmptyApps,
+                )
+
+    def test_explicit_default_app_config_without_apps(self):
+        """
+        Load an app that specifies a default AppConfig class in __init__ and do
+        not have an apps module.
+        """
+        msg = (
+            "'apps.explicit_default_config_without_apps' defines "
+            "default_app_config = 'apps.explicit_default_config_without_apps."
+            "ExplicitDefaultConfigWithoutApps'. However, Django's automatic "
+            "detection did not find this configuration. You should move the "
+            "default config class to the apps submodule of your application "
+            "and, if this module defines several config classes, mark the "
+            "default one with default = True."
+        )
+        with self.assertRaisesMessage(RemovedInDjango41Warning, msg):
+            with self.settings(INSTALLED_APPS=['apps.explicit_default_config_without_apps']):
+                pass
+        with ignore_warnings(category=RemovedInDjango41Warning):
+            with self.settings(INSTALLED_APPS=['apps.explicit_default_config_without_apps']):
+                self.assertIsInstance(
+                    apps.get_app_config('explicit_default_config_without_apps'),
+                    ExplicitDefaultConfigWithoutApps,
+                )