ZipRecruiter Machine Learning Engineer Interview Experience — A CodeSignal Bug Hunt in Go

I haven't seen a ZipRecruiter MLE interview report on the forum before, so let me share my first-round experience:

The recruiter told me it would be on CodeSignal, using some obscure language to find a bug, and that I could ask the interviewer syntax-related questions.

The interviewer was a senior software engineer with 4 years at the company. He introduced himself first, then had me introduce myself and talk about what skills/tools I know. Then we switched over to the CodeSignal interface to look at the problem — we had about 45 minutes to work on it. The language was Go, and it really wasn't about syntax, so don't worry too much about which specific language it is. On the right side of the screen it said this was a bug-finding problem for a laptop device management system: each laptop comes with corresponding hardware, like earbuds, mouse, keyboard, etc., and each laptop corresponds to one or a few users. The question was: if you enter these four commands in this order, the system doesn't throw an error (This works), but if you enter another four commands, the system throws an error (This doesn't work) — find where the problem is. It's not necessarily a one-line fix, could be a few lines. The commands given in the problem were:

First, in the input environment: env user=George

Then, This works:
go laptop — shows what laptops George has (output: dell, m2, mac)
go pick dell
go list dell features (output is empty)
go update dell features (waits for user input on what hardware to update, like earbuds, keyboard)

However, This doesn't work:
go pick m2
go list m2 features (m2 already has 4 pieces of hardware, A B C D)
go update dell features (shows all selectable hardware, A B C D are all in there, but only A has a checkmark in front of it — this is clearly where the bug is) — user inputs AB, system throws an error (exit 1)

The interviewer was friendly about answering my questions on understanding the problem, hinted that I could type commands directly into the terminal instead of clicking Run, and confirmed when I was on the right track during my analysis.

I'm not that strong, so I didn't manage to actually fix the bug, but I did analyze it and told him the bug was probably in that one small section. Interviewed at 10:30am, got the rejection email at 7pm the same day.

The interviewer said the company has roughly 15 people doing MLE work, some of whom actually have the title SDE. The recruiter said multiple teams are hiring for MLE right now.