Agreed that a lot of interviewing issues that I've seen boil down to a misunderstanding of the rules/expectations of an interview, which can be problematic on both sides. Some examples:
* I've had candidates do poorly on a warm-up question because they expect it will be difficult. Ideally, they would say the easy answer they know, but I've had candidates stay quiet while thinking of a hard solution that doesn't exist, then get frustrated when they find that the easy answer is what I was looking for. On my end, this problem is especially tricky because I don't necessarily want to say that something is a warm-up question.
* I've had candidates who have had trouble because they viewed problems as either too concrete or too open-ended. In some cases, I hope that candidates will notice ambiguities in the problem and ask clarifying questions, or come up with creative alternate solutions. In other cases, I know that a particular high-level structure makes a good, consistent problem, and I want them to follow that structure.
* I've had candidates who have written code that's either too hacky/messy/unpolished or too professional such that it slows them down.
My best advice to interviewers is to be straightforward about expectations and open-minded about what assumptions the candidate might have coming in. For example, these days, I try to explain the code quality balance I'm looking for, something like "I'm looking for reasonably production-quality code that might pass code review, but it's still an interview setting, so it's fine to leave off things like docs and unit tests".
I think my best advice to interviewees is to keep a conversation going and be open about your thought process and your assumptions. If you're interpreting the problem wrong, a reasonable interviewer should be able to notice and correct that. The main failure mode I've seen here is people being hesitant to communicate their thought process or ask clarifying questions, which means the interviewer isn't able to know when the candidate is doing poorly because they've misunderstood the problem.
I really liked this type of interview. It's not so much an evaluation of coding skill as it is a way to get to know the candidate.
With offers lined up, I turned down interview invites from other shops that were publicly complaining about talent shortage and simultaneously had a needlessly complicated & time consuming interview pipeline. I think companies are overthinking it.
First, if you truly believe that the code I showed is "a snippet of code completely made up or taken out of context and then anonymized by renaming variables", I can only say that I don't believe you've ever worked on large codebases. There are millions of lines of code, in hundreds of thousands of application, in dozens of different languages, all over the world, precisely like the snipped I showed. If you've been coding for 20 years, as you say you have, and haven't seen snippets like that on a thousand occasions, you must have worked in very strange environments. If you really want me to, I'll spend 5 minutes and give you multiple links to exactly similar snippets in various large open source projects.
Second, I'm mystified by your comments regarding my trivially simple code question. that "Interviewers come up with their games with their arbitrary rules and a bunch of prejudice about how a good or bad candidate should react".
Wut? Let's make the question even simpler:
X := Y / Z
"This looks like a snippet of code completely made up or taken out of context and then anonymized by renaming variables. I have no idea what it's supposed to do, I have no idea why I'm looking at it, and I have no fucking idea what you want from me, and I don't play guess-the-rules type of games."
Are you seriously telling me that you'd hire a candidate who said that? Over one who said, "What if Z is zero?" ?
I think one of us is missing something...
So it's hard to engage meaningfully. Give me motivation. Tell me what I'm doing or why I'm looking at this code in the first place. Show me the context and maybe I will see whether I should care about Z possibly being zero or not. Tell me what the language is or how it handles divide by zero (does it have exceptions?) and I might figure out that we don't give a fuck about divide by zero because it's handled elsewhere or not at all relevant to this snippet. I regularly write divisions without zero check because I know the divisor is a positive compile time constant. Here, I just see a snippet out of context; again my thought is "what the hell does this guy want from me?" Show me real code with real context and a real purpose so we can talk real talk.
What's wrong with my x /= z;? Nothing, it's doing the perspective divide just right. And you don't go about checking for divide by zero because I've already clipped my primitives. There's nothing wrong with the names either.
Sure the snippet you posted could be a snippet from some real codebase but without context it is nothing. What do you think of 100101010100000100010001000110? Sorry, wrong answer! Next guy please. That's also real binary from a real file and it's easy to figure out what it says but hard to say what I want from you. Try it!
> I can only say that I don't believe you've ever worked on large codebases.
I don't suppose the operating systems and web browsers I've worked on are the largest of them all but damn. You can keep your religion though.
There we agree!
In your first snippet, would you expect a candidate to tell you that `f` might be undefined?
No. Because I'd expect the candidate to focus on subtle issues, and not waste time on bleeding obvious ones!
Of course f() might be undefined. Blind Freddy knows that. But Blind Freddy can't necessarily see the other (much more subtle) problems in those 4 lines of code.
I want to know, is this candidate more than Blind Freddy? Does he inhabit what some of us call "the real world", where things like division by zero are things to be consciously managed by proper coding practices?
(Edits for clarity)
But its the lack of communication on your front that would make people fail your test, not their lack of competence.
Anyone can summon an obscure puzzle and claim its easy when they know the key.
isn't this a bit reductive?
I posted a detailed exposition of my own approach to interviewing. I expected nothing more than some intelligent comments thereon.
In response, someone says I'm "prejudiced", and why would he "give a fuck" about my concerns; another says my concerns exist "in a parallel universe"; and another says my views are "religious"!
Equeeze me if I don't take well to copping random insults in what is meant to be an intelligent discussion forum. Particularly from people who've contributed zero to the discussion so far - like you! I suggest you get out of the basement and get some exercise. Maybe ask your mum for a bike?
My first thought is, "This looks like a snippet of code completely made up or taken out of context and then anonymized by renaming variables. I have no idea what it's supposed to do, I have no idea why I'm looking at it, and I have no fucking idea what the interviewer wants form me, and I don't play guess-the-rules type of games." If this were real code, I'd have context. Not just a snippet. I'd see the things I don't see in the snippet, and I'd know why I'm looking at it and what I'm looking for. In real work, there is always a motivation for everything you do. In this case, there is none. You might as well show a sequence of bits. "What do you think of these bits?"
So by your prejudice, you'd probably categorize me in the first camp. Congrats, you probably turned down someone who's been coding for 20 years. Then again, if this really is the kind of line of business code you regularly deal with, maybe it's for the (my) best.
This is a pattern I see all the time. Interviewers come up with their games with their arbitrary rules and a bunch of prejudice about how a good or bad candidate should react. They think they came up with something clever, they always do. They have no idea.
I get the impression that good people get regularly turned down because they didn't guess the rules of the game right, or they don't even play because they got an offer at some place that doesn't play these silly games. Then there is so much complaining about talent shortage, and complaining about terrible interview practices, and complaining about having to deal with a stack of 1000 job applications.