Reviewing code you’re not familiar with

We’ve all had to do code reviews on bits of code we weren’t very familiar with. Whether it’s part of the application you haven’t worked on before or a new hire who’s looking at the code-base for the first time, it’s never obvious what to look for, how to determine if the implementation details are bug-free, or how in-depth you should go. The natural instinct, at least for me, is to gloss over the higher-level concepts and look only for obvious mistakes in the implementation details. So how do you get up to speed quickly, figure out what needs attention and doesn’t, and find potential issues with the implementation? As it turns out, a lot of it relies on what the person creating the code review makes available to you as the reviewer.