[2.2.x] Fixed #30318 -- Added check for importability of arguments of custom error handler views.

Thanks to Jon on Stack Overflow for reporting the issue.

Backport of a5accc0368c6575b55976c06af36ed399c85c781 from master

2 files changed, 29 insertions, 0 deletions

diff --git a/tests/check_framework/test_urls.py b/tests/check_framework/test_urls.py
index 67de26c690..217b5e7bad 100644
--- a/tests/check_framework/test_urls.py
+++ b/tests/check_framework/test_urls.py
@@ -181,6 +181,29 @@ class CheckCustomErrorHandlersTests(SimpleTestCase):
                     id='urls.E007',
                 ))
 
+    @override_settings(ROOT_URLCONF='check_framework.urls.bad_error_handlers_invalid_path')
+    def test_bad_handlers_invalid_path(self):
+        result = check_url_config(None)
+        paths = [
+            'django.views.bad_handler',
+            'django.invalid_module.bad_handler',
+            'invalid_module.bad_handler',
+            'django',
+        ]
+        hints = [
+            "Could not import '{}'. View does not exist in module django.views.",
+            "Could not import '{}'. Parent module django.invalid_module does not exist.",
+            "No module named 'invalid_module'",
+            "Could not import '{}'. The path must be fully qualified.",
+        ]
+        for code, path, hint, error in zip([400, 403, 404, 500], paths, hints, result):
+            with self.subTest('handler{}'.format(code)):
+                self.assertEqual(error, Error(
+                    "The custom handler{} view '{}' could not be imported.".format(code, path),
+                    hint=hint.format(path),
+                    id='urls.E008',
+                ))
+
     @override_settings(ROOT_URLCONF='check_framework.urls.good_error_handlers')
     def test_good_handlers(self):
         result = check_url_config(None)
diff --git a/tests/check_framework/urls/bad_error_handlers_invalid_path.py b/tests/check_framework/urls/bad_error_handlers_invalid_path.py
new file mode 100644
index 0000000000..77e0c639e0
--- /dev/null
+++ b/tests/check_framework/urls/bad_error_handlers_invalid_path.py
@@ -0,0 +1,6 @@
+urlpatterns = []
+
+handler400 = 'django.views.bad_handler'
+handler403 = 'django.invalid_module.bad_handler'
+handler404 = 'invalid_module.bad_handler'
+handler500 = 'django'