The unreasonable effectiveness of an LLM agent loop with tool use

This morning I used cursor to extract a few complex parts of my game prototype's "main loop", and then generate a suite of tests for those parts. In total I have 341 tests written by Cursor covering all the core math and other components.

It has been a bit like herding cats sometimes, it will run away with a bad idea real fast, but the more constraints I give it telling it what to use, where to put it, giving it a file for a template, telling it what not to do, the better the results I get.

In total it's given me 3500 lines of test code that I didn't need to write, don't need to fix, and can delete and regenerate if underlying assumptions change. It's also helped tune difficulty curves, generate mission variations and more.

Writing tests, in my experience, is by far the best use case for LLMs. It eliminates hours or days of drudgery and toil, and can provide coverage of so many more edge cases that I can think of myself. Plus it makes your code more robust! It’s just wonderful all around.

Yeah I generated another 60 tests / 500 lines of test code since I posted my comment. I must have written 100,000s of lines of test codes the hard way, it's not just faster than me it's better than me when it comes to the coverage, and it requires less of my help than a number of developers I've had under me.