Should it be that way?

rest_framework/tests/test_validation.py

@@ -61,6 +61,8 @@ class TestPreSaveValidationExclusionsSerializer(TestCase):
         # does not have `blank=True`, so this serializer should not validate.
         serializer = ShouldValidateModelSerializer(data={'renamed': ''})
         self.assertEqual(serializer.is_valid(), False)
+        self.assertIn('renamed', serializer.errors)
+        self.assertNotIn('should_validate_field', serializer.errors)
 
 
 class ValidationSerializer(serializers.Serializer):