I never heard of shepherds testing their Estrelas in any way...I understand that it may be a costume in the balcans and in caucasus, but we should understand that in many places that doesen´t exist and doesen´t need to exist. Here in Portugal shepherds often don´t even choose their breeders and when they do they choose them based in their working abilities. You must not forget that shepherds often have more than one dog and as a pack animal dogs often fight with eachother and build up their hierarchy. Shepherds are often aware of this and naturaly tend to choose as breeders the alpha dogs.