Refs #33348 -- Made SimpleTestCase.assertFormError() raise ValueError when "field" is passed without "form_index".

django/test/testcases.py

@@ -658,6 +658,10 @@ class SimpleTestCase(unittest.TestCase):
                 stacklevel=2,
             )
             errors = []
+
+        if form_index is None and field is not None:
+            raise ValueError("You must use field=None with form_index=None.")
+
         # Put error(s) into a list to simplify processing.
         errors = to_list(errors)
 

tests/test_utils/tests.py

@@ -1603,6 +1603,17 @@ class AssertFormsetErrorTests(SimpleTestCase):
         )
         self.assertFormsetError(response, "formset", None, None, "error")
 
+    def test_non_form_errors_with_field(self):
+        response = mock.Mock(
+            context=[
+                {},
+                {"formset": TestFormset.invalid(nonform=True)},
+            ]
+        )
+        msg = "You must use field=None with form_index=None."
+        with self.assertRaisesMessage(ValueError, msg):
+            self.assertFormsetError(response, "formset", None, "field", "error")
+
     def test_form_index_too_big(self):
         msg = (
             "The formset <TestFormset: bound=True valid=False total_forms=1> only has "