We could design meat eating robots that will hunt you down and kill you and thereby test your mental and physical abilities. We could program so they are just the right intelligence, not too smart, not too fast.

"From the file marked “Evidently, many scientists have never seen even one scary sci-fi movie”: The Defense Department is funding research into battlefield robots that power themselves by eating human corpses. What could possibly go wrong?

Since they apparently don’t own TVs or DVD players, researchers at Robotic Technology say the robots will collect organic matter, which “could” include human corpses, to use for fuel. But if you picked up anything on flesh-eating robots over the years you know they’ll ignore that tasty soybean field and make a chow line right to the nearest dead body. And, if the machines can’t find enough dead people to eat, they can always make new ones."

[link to www.wired.com]

I guess you could argue that's what animals are, meat eating robots but they do not merely eat to be eating, they eat to live, not live to eat. Only humans live to eat.