Bugs in code is not a lot of fun at the best of times, but finding a bug in a mocking library is the sort of thing that can really ruin your day, or week, or worse.
The past few days I‘ve been deep in a refactor, and I eventually hit a point where I was fighting the tools rather than the code. There were just too many moving parts, and it became impossible to see the woods for the trees. What appeared to be a straightforward bug in my integration tests turned into a two-day troubleshooting marathon. It’s a strange irony of working with LLMs: the ability to generate code so quickly means you can sometimes dig yourself into an even deeper hole than the one you are already in, with terrifying efficiency. You end up iterating on a flawed premise until you’re so far down you’ve lost all perspective on the original problem.
My way out of that cycle is to step away from the main project and build a "minimal". I’ve been doing this for years. I’ve even started a dedicated section in my portfolio to track them. The goal is to isolate the problem domain completely. By stripping everything back to a few lines of code and a single test case, the friction has nowhere to hide. In this case, it turned out that Node’s native fetch behaves just differently enough during a 204 handshake to throw Nock into a tailspin unless you explicitly override the transport.
I don't just build these repos to fix a single bug, they serve as a way to document the "why" so my future self can return to the problem and actually remember the details. It’s easy to forget the nuances of a library conflict six months down the line, but having a working, isolated example provides a path back to stable ground. It’s about being pragmatic, clearing the brambles in a small patch so you can see the through-line in your main project.
Here's the latest minimal: minimal-modern-node-http-mocking
The good news is that when I dove back into the main project I was able to fix the integration test I had been spinning on almost immediately. I feel like this latest minimal is a textbook example of when to use this technique.
Side note, a long list of very strange synchronicities for me this week, including what seemed like a name drop of the mocking library in a podcast I listened to moments after deciding to fix the bug. What's really weird, as far as I can tell they were talking about something completely unrelated to programming. It made no sense whatsoever in their context. #