If someone made it to an onsite and you don’t know whether they can add a button in swift, something failed in your screening process. If you’re testing how someone navigates a codebase, you can just look at it with them, and let them drive the chat.
If you’re testing an engineer for a serious job, do an algorithms test. If you’re testing an engineer for a specific thing, test that specific thing. Both of those should be handled in the screen, not the onsite.
IMHO, the onsite is about seeing how people think. Whether you can jam a button into a repo doesn’t tell me whether you can think or not. I guess it tells me whether you get flustered, but it’s pretty unfair to design things that are impossible just to see if people break.
That candidate turned out to be awesome but I remember the interviewer telling me after they interviewed them “well, they couldn’t add the button, but as they were doing it, I realized I wouldn’t be able to add the button either so my interview was inconclusive”, and I replied “well it sounds like you need to design a better interview question”. The worst part was, the interviewer spent the first 20 minutes of the interview talking with the candidate before giving them 25 minutes to add the button!!
There’s a question we gave candidates really early on which we no longer do because it biases towards math nerds that I absolutely loved. It’s based on a movie called 13 Tzameti. I’m probably screwing it up because it isn’t my question but it’s basically like this:
You’re in a dark room after being abducted by a gang. The lights come on and there’s 12 other people in the room in a circle and everyone has a revolver with 1 bullet in it (6 slots in the chamber). Your instructions are to spin the chamber on the revolver and, when the lights go out, shoot the person to your right in order.
What are the odds you make it to the next round?
It’s a crazy question and, what’s even crazier is that for some reason, as you increase the number of people in the circle, the odds of making it to the next round converge on 1/e. No one has figured that out in the interview. Also no one has figured out why it converges on 1/e so if you have any ideas, let me know.
I like this question because it shows you how free thinking people are. I dislike this question because it biases towards smartasses and probability nerds.