The year of interviews
A few years ago the company I worked for had a period of intense hiring. Over the course of a year I conducted at least 1-2 interviews pr week, so I ended up taking an active part in shaping our process.
My interviews were usually focused on technical skills for platform engineers or developers, and the main topic was often; “How do we know that they can code?” This was also the part we struggled the most with to get right.
In the beginning we used the classic leet code exercises, which I personally just don’t like. It’s easy to study a bunch of them and they are often hard to do under pressure, which can make you miss out on some good people and get a false positive for others.
So we introduced a live coding challenge where we asked people to start coding a battle ship game. The goal was never to complete it but to discuss and more or less write code together. For me this was a perfect way to demonstrate technical skills in a non-threatening environment. But a lot of people were put off by live coding and simply froze or make lot’s simple mistakes they would never make normally.
This caused us to give up on the live coding, and instead give it as a “home assignment”. As a live coding exercise it had been obvious that nobody could complete the assignment, but now when given as a home assignment people felt the need to complete it, and spent way too much time on the task. I also never liked home assignment for this reason, as I feel it’s way too much to ask of a candidate who might have 4 or 5 interviews lined up with various companies to do home assignments for all of them in addition to their current job. We also had a couple of candidate show up with code they couldn’t explain.
The ‘aha moment’
Then while we were on-boarding a new team member, and we were reviewing a pull request together I realized something. What we are trying to do is to put the candidate in a “life like situation” and test their technical abilities. But that doesn’t mean we have to make them write code. While we were reviewing this pull request I got so much information about how our new team member thinks, how they communicate about the work of others, how they write comments on ways the pull request author can improve. And all of this requires the technical skills that we are trying to assess in the first place.
So a week or so later I got to try my “Live pull request review” in an interview. I pulled out a medium+ sized pull request which added a new feature to one of our platform tools and printed it out on paper. After giving an introduction to the tool and the intention of the pull request I asked the candidate to review the pull request with me and we took notes of all the feedback we had.
I only got to do 4 or 5 of these interviews before we cut back on hiring, but my experience with this approach were really good. The candidates were much less intimidated by this than by live coding and there is no “homework”. I also made it clear that this code is written by a potential future team mate and that they will receive the feedback we write. To me this part is crucial because it shows how they communicate to others and give feedback, which is a key part of learning and spreading knowledge.
The other part of this is that after wrapping up the code review, it’s natural to go into a discussion about what happens next. How should the code be tested, what options do we have for deployment. Let’s say we’ve deployed this application and it fails with X, how do we troubleshoot? Since we’ve already gotten into a collaborative setting, these types of explorations are natural to move into and they give so much better understanding of someones skills rather than having a test where they need to remember the implementation details of quicksort. And as an interviewer these types of interviews are much more rewarding and require much less preparation.
There are no silver bullets in hiring as you’re trying to get the experience from a month of working together into an hour, but making the experience as enjoyable as possible and avoiding both live coding and home work seem like good goals to me. And the quicker we’re able to move away from scripted questions into natural conversation the better.