Refs #32508 -- Raised Type/ValueError instead of using "assert" in django.core.

tests/check_framework/tests.py

@@ -4,6 +4,7 @@ from io import StringIO
 from django.apps import apps
 from django.core import checks
 from django.core.checks import Error, Warning
+from django.core.checks.messages import CheckMessage
 from django.core.checks.registry import CheckRegistry
 from django.core.management import call_command
 from django.core.management.base import CommandError
@@ -74,6 +75,20 @@ class SystemCheckFrameworkTests(SimpleTestCase):
             def no_kwargs(app_configs, databases):
                 pass
 
+    def test_register_run_checks_non_iterable(self):
+        registry = CheckRegistry()
+
+        @registry.register
+        def return_non_iterable(**kwargs):
+            return Error('Message')
+
+        msg = (
+            'The function %r did not return a list. All functions registered '
+            'with the checks registry must return a list.' % return_non_iterable
+        )
+        with self.assertRaisesMessage(TypeError, msg):
+            registry.run_checks()
+
 
 class MessageTests(SimpleTestCase):
 
@@ -132,6 +147,11 @@ class MessageTests(SimpleTestCase):
         e = Error("Error", obj=DummyObj())
         self.assertNotEqual(e, 'a string')
 
+    def test_invalid_level(self):
+        msg = 'The first argument should be level.'
+        with self.assertRaisesMessage(TypeError, msg):
+            CheckMessage('ERROR', 'Message')
+
 
 def simple_system_check(**kwargs):
     simple_system_check.kwargs = kwargs