Refs #29713 -- Improved error message when LANGUAGE_CODE is invalid.

django/core/checks/translation.py

@@ -4,16 +4,15 @@ from django.utils.translation.trans_real import language_code_re
 from . import Error, Tags, register
 
 E001 = Error(
-    'You have provided an invalid value for the LANGUAGE_CODE setting.',
+    'You have provided an invalid value for the LANGUAGE_CODE setting: {}.',
     id='translation.E001',
 )
 
 
 @register(Tags.translation)
 def check_setting_language_code(app_configs, **kwargs):
-    """
-    Errors if language code setting is invalid.
-    """
-    if not language_code_re.match(settings.LANGUAGE_CODE):
-        return [E001]
+    """Error if LANGUAGE_CODE setting is invalid."""
+    tag = settings.LANGUAGE_CODE
+    if not isinstance(tag, str) or not language_code_re.match(tag):
+        return [Error(E001.msg.format(tag), id=E001.id)]
     return []

docs/ref/checks.txt

@@ -440,7 +440,7 @@ Translation
 The following checks are performed on your translation configuration:
 
 * **translation.E001**: You have provided an invalid value for the
-  :setting:`LANGUAGE_CODE` setting.
+  :setting:`LANGUAGE_CODE` setting: ``<value>``.
 
 URLs
 ----

tests/check_framework/test_translation.py

@@ -1,5 +1,6 @@
-from django.core.checks.translation import E001, check_setting_language_code
-from django.test import SimpleTestCase, override_settings
+from django.core.checks import Error
+from django.core.checks.translation import check_setting_language_code
+from django.test import SimpleTestCase
 
 
 class TranslationCheckTests(SimpleTestCase):
@@ -22,6 +23,9 @@ class TranslationCheckTests(SimpleTestCase):
 
     def test_invalid_language_code(self):
         tags = (
+            None,              # invalid type: None.
+            123,               # invalid type: int.
+            b'en',             # invalid type: bytes.
             'eü',              # non-latin characters.
             'en_US',           # locale format.
             'en--us',          # empty subtag.
@@ -33,9 +37,9 @@ class TranslationCheckTests(SimpleTestCase):
             # FIXME: The following should be invalid:
             # 'sr@latin',      # locale instead of language tag.
         )
+        msg = 'You have provided an invalid value for the LANGUAGE_CODE setting: %s.'
         for tag in tags:
-            with self.subTest(tag), override_settings(LANGUAGE_CODE=tag):
-                result = check_setting_language_code(None)
-                self.assertEqual(result, [E001])
-                self.assertEqual(result[0].id, 'translation.E001')
-                self.assertEqual(result[0].msg, 'You have provided an invalid value for the LANGUAGE_CODE setting.')
+            with self.subTest(tag), self.settings(LANGUAGE_CODE=tag):
+                self.assertEqual(check_setting_language_code(None), [
+                    Error(msg % tag, id='translation.E001'),
+                ])