To verify that they can bang out code when they need to, not just when they're in the right frame of mind to create code samples. Also, ours is domain specific and measures multiple things about the candidate (but the primary one is just that they can produce sane code).
In this case, we're talking about FizzBuzz. The point of FizzBuzz is that it's a test that can be passed by literally anyone with an elementary ability to code. Optimizing for it is silly. Just bang out the fizzbuzz answer (make fun of it if you like) and get on with your life.
I'm obviously against any quizzes in an interview; it puts the interviewer and the interviewee on unequal footing, but that's not the point in my comment. I'm not optimizing for fizzbuzz here. I'm optimizing for "I'm not some guy off the street here, here's some proof". I'm optimizing for "let's skip past the bullshit".
Except that it's not bullshit, at least not in the traditional sense. Think of it like your most basic unit test. Regardless of what the evidence suggests, can the candidate bang out a quick algorithm, without aid, in your presence?
Interviews are a HUGE time sink for companies; not just in the interview itself, but also in the examination of candidates, their resumes, their code, their references, discussions among team members to decide if they'll be a good fit, etc, etc. One interviewee can blow away two days work easy. So we're not in the mind to lose any more time than we have to.
Fizzbuzz is a sanity test. To the candidate it may seem absurd, but once as an interviewer you've dealt with enough fakers, or even people who honestly believe they can code and yet can't, you begin to appreciate the simple elegance of a 5 minute fizzbuzz test as a kick-off to the interview.
You're assuming that the person interviewing trusts your absolutely in your statement that that code is yours.
They can't assume that. It would be irresponsible of them to just assume that that is proof of your abilities. Whilst fizzbuzz doesn't prove anything either, if you fail it then they know that you are lying. It's better than just blindly accepting it.
Interviewers don't owe you anything. If you are over-qualified then within five minutes of talking you should be able to prove to them that you are worth skipping over the bullshit.
If the person still wants to go forward then that would decrease the value or working at that company in my mind.
