Subtle Testing Mistakes Claude Code Makes

Mistakes in React/Redux testing code quality that anyone can do, even Claude Code.

Generated by the author.

Last week, I used Claude Code to generate the repository for the article, in which I explained how to leverage on React/Redux code to speed up tests 100x times. At first glance, the code seemed right, but it was full of mistakes hiding in plain sight. Errors that any of us can make. So, in this article I will explain them, and along the way you will be able to take away various ideas to improve your testing code.

Indeed, it must be said, Claude Code’s overall performance was extraordinary. And on just a few occasions did I have to modify the code. It not only wrote code, but also ran the tests, extracted the metrics, and built the tables.

Does not remove old files

The first thing I did was to ask it to encapsulate all the demos that existed up to that point (the Humble Object pattern, explained two articles ago) within a folder called plain.

But it didn’t do it as well as expected. It created the structure, but didn’t delete the old files. That is, it didn’t move them, but copied them.

And this isn’t the first time I’ve encountered this problem. In other projects it has repeated the same issue…