If you really want the position, you will put a lot of effort into researching what the interview will entail.
If you're a hard worker, you will intensively study for the interview.
If you're smart, you'll be able to apply the material you studied to the problem, and you'll probably realize the game you're playing.
None of these things is about 'engineering skill', which is much more difficult to discover, and only really valuable if the person is a smart, hard worker, who sticks around.
*edit: I am not saying that I like this style of interview, and when I interview job candidates, I never engage in this type of 'test'