This is one of the best "side-effects" of testing, with the reasoning is that testable code is good code (as in modular, cohesive, etc...)

Games are likely to benefit significantly from unit tests: architecture is complex and likely to be improved by adding clean boundaries and layers for the sake of testability; supporting automation is likely to enable useful features (e.g. deterministic simulations); tests are likely to be meaningful and important.

Have you developed games at all, or are you just speaking from an armchair?

As a gamedev who writes unit tests, I agree with GP. Games benefit from unit tests. That, however, doesn't change the systemic incentives that prevent tests from being written. The ways that gamedev is budgeted/funded is a more important factor than more tests = a more stable/less buggy game.

What engine do you use that supports a unit test framework?

Since testing in game development is very much underrated, it would be interesting to hear more about this. Was this just as a hobby or is the game available somewhere? And have you ever done a demo/talk about how you've approached unit testing with Unity?

not unit testing but a good talk on one team's testing

https://m.youtube.com/watch?v=m5zrfTFKf_E

I’ve found that while I did spend a lot of time at first figuring out how to write testable code, I now am so much better at writing in this way that I am much more productive since everything has great test coverage. Saves me going back to modules I wrote 2 years ago to add features.