The best received interview question we used to give was for a role that involved fixing existing code bugs. The technique to design such a question: distill an

The best received interview question we used to give was for a role that involved fixing existing code bugs. The technique to design such a question: distill an actual problem your team faced recently into something a competent developer could solve in about 15 minutes. The problem: we had a credit reset script that users complained about. Apparently it gave incorrect resets. We sanitized the db tables needed and introduced a couple more simple bugs in the data, sanitized the script and provided a couple different language adaptations with a couple added logic bugs. The candidate was given access to the repo and it had a clean way to reset the tables. The candidate had 45 minutes to fix the issue in the associated bug report tickets. We received so many compliments from candidates, even those who were not hired. TL;DR: design a work sample test and give that. Base it on recent work. Give the candidate 3x the time to solve it than what it takes you or a midlevel dev on your team to solve.