I have a long answer to this which I can dredge up and copy paste. Here's the short version.
1/3 random questions from the immigration test as it exists today (so that no one can disenfranchise others by changing the test).
2/3 questions chosen by each candidate on the ballot. Questions must have an objectively correct answer and must be pertinent to the powers of the office itself.
The long version of this answer just adds defining objective, correct, and pertinent in a legally unambiguous way and sketches out scenarios like trick questions to show that the only reliable way to gain favor in this system is to actually be knowledgeable.