I have mixed feelings about this sort of thing. As an interviewer I've done something like this when needing to hire for a very straightforward job with very l

I have mixed feelings about this sort of thing. As an interviewer I've done something like this when needing to hire for a very straightforward job with very little time and an effectively endless supply of candidates. This addressed the problem of our time crunch, but I doubt it helped the selection process overall. I think this sort of testing is subject to all the same issues as most any other method of interviewing, but limited to a much smaller sample size. Basically, it's arguably good for the interviewers and a coin flip for everyone else. As an interviewee, I haven't encountered a test like this, but I expect my response would almost surely involve questioning the architecture decisions that led to such a problem in the first place.