          """
          We do not support update on already sliced query sets.
          """
          method = DataPoint.objects.all()[:2].update
          with self.assertRaises(AssertionError):
              method(another_value='another thing')
  
      def test_update_respects_to_field(self):
          """
          Update of an FK field which specifies a to_field works.
 
</s> remove         with self.assertRaises(AttributeError):
 </s> add         msg = "'CustomQuerySet' object has no attribute 'manager_only'"
        with self.assertRaisesMessage(AttributeError, msg): </s> remove         with self.assertRaises(FieldError):
 </s> add         msg = "Unsupported lookup 'blahblah' for CharField or join on the field not permitted."
        with self.assertRaisesMessage(FieldError, msg): </s> remove         with self.assertRaises(FieldError):
 </s> add         msg = 'Joined field references are not permitted in this query'
        with self.assertRaisesMessage(FieldError, msg): </s> remove         with self.assertRaises(ImproperlyConfigured):
 </s> add         msg = "'apps.apps.NotAConfig' isn't a subclass of AppConfig."
        with self.assertRaisesMessage(ImproperlyConfigured, msg): </s> remove         with self.assertRaises(ImproperlyConfigured):
 </s> add         msg = (
            "TemplateResponseMixin requires either a definition of "
            "'template_name' or an implementation of 'get_template_names()'"
        )
        with self.assertRaisesMessage(ImproperlyConfigured, msg):
        msg = 'Cannot update a query once a slice has been taken.'
        with self.assertRaisesMessage(AssertionError, msg):
          """
          We do not support update on already sliced query sets.
          """
          method = DataPoint.objects.all()[:2].update
        msg = 'Cannot update a query once a slice has been taken.'
        with self.assertRaisesMessage(AssertionError, msg):
              method(another_value='another thing')
  
      def test_update_respects_to_field(self):
          """
          Update of an FK field which specifies a to_field works.
keep keep keep keep replace keep keep keep keep keep
 Used assertRaisesMessage() to test Django's error messages. 
tests/update/tests.py