I believe earily puppy testing is the only valid measure of the natural temperment.
In the earily days & weeks the pupies have not yet be influenced by humans. The earily temperment traits are still pure.
ALL puppies no matter what breed are "sponges" soaking up information from thier environment, taking clues from thier humans. Even in a 8 wk puppy class one observes vast changes in a 12wk old puppy as it learns acceptible behavior from it's owner.
A dog's temperment is a constant however, they do learn (or Not learn) how to control themselfs so that they fit within thier own packs.