Years ago I was giving a talk on software development and asked the audience how long it takes to review a PR that has 10 lines changed. Answers were in the minutes to tens of minutes range. I then asked how long it takes to review a PR that has 1,000 lines changed. Some people said hours, but a few people said seconds.
I’ve often taken the latter, pessimistic view. Not because I don’t think engineers want to do a good job, but because I know human behavior. Most humans will get bored, lose focus, and end up skimming through a large amount of code. Many (most?) people don’t want to spend all that time, after all they have they their own code to write. They’ll just approve the PR and assume testing will catch any major issues.
Even if a reviewer wants to do a great job, they likely will still miss things. It’s very hard to focus across that much code.
This is a funny visual (from X) about code reviews. It’s titled “me reviewing code written by Claude before pushing it to production.” Plenty of people are probably laughing, or thinking this is a good reason to not use an AI to write code.
However, I don’t think the problem is an AI writing code. If you trust the AI without reviewing things, that’s on you. You deserve blame if things fall apart.
The bigger problem is that an AI can write code so quickly and can make so many changes that PRs will tend to be large. These changes will tend to not get human-reviewed with any level of focus or quality control. The problem is volume, not who wrote the code (or the quality). Certainly quality matters, but it’s easy to catch changes if you have a small volume of code. Harder if you have a lot.
The more I use AI for spot work, to handle tedious things, to do something like subtly adjust spacing in a UI or focus on adjusting a few things in a data model, the easier it is to judge the focus and quality of the code. Is the change doing the job I need done, and is it doing it well?
Code quality is a problem we’ve had ever since we started writing code. AI can make the problem worse, not because of poor coding, but because it will write so much code in a PR that you can’t review it appropriately.
Steve Jones
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