def METHOD_NAME(self, mocked):
    # Receiver for Django signals involved in PATCHes to SIA Signal instances
    fake_receiver = unittest.mock.MagicMock()
    update_location.connect(fake_receiver)
    update_status.connect(fake_receiver)
    update_category_assignment.connect(fake_receiver)
    update_priority.connect(fake_receiver)
    create_note.connect(fake_receiver)
    update_type.connect(fake_receiver)
    # Perform a PATCH with in,valid category assignment:
    self.client.force_authenticate(user=self.sia_read_write_user)
    detail_endpoint = self.detail_endpoint.format(pk=self.signal.id)
    mocked.side_effect = ValidationError('Something, something, error!')
    self.payload['category']['sub_category'] = self.link_test_cat_sub
    response = self.client.patch(detail_endpoint, data=self.payload, format='json')
    self.assertEqual(response.status_code, 400)
    # Assert that our fake receiver was never called.
    fake_receiver.assert_not_called()