Making games in Go: 3 months without LLMs vs. 3 days with LLMs

The problem with tests for games is that a lot of game code is in constant flux. A test suite introduces a not insignificant amount of rigidity to your codebase. Pivot a few concepts and you have dozens of tests to fix - or just invalidate entirely. Very basic stuff that won't ever change can be tested - like whether the renderer is working properly - but that's never where the difficulty in game dev lies and its the stuff usually handled by a third party - library or engine.

> The problem with tests for games is that a lot of game code is in constant flux. A test suite introduces a not insignificant amount of rigidity to your codebase. Pivot a few concepts and you have dozens of tests to fix - or just invalidate entirely.

Sounds very much like the description of a big ball of mud.

An interesting gamedev video I saw recently basically boiled down to: "Build systems, not games." It was aimed at indie devs to help with the issue of always chasing new projects and making code that's modular enough to be able to reuse it.

But taking a step back, that very much feels like it should apply to entire games, where you should have boundaries between the components and so that the scope of any such pivot is managed well enough not to tank your velocity.

Other than that, it'd be just the regular growing pains of TDD or even just needing to manage good test coverage - saying that tests will eventually need changes isn't the best argument against them in webdev, nor should it be anywhere else.

> Sounds very much like the description of a big ball of mud.

I mean, yeah, kinda.

For any given object in the game world, it's funnest for that object to be able to interact with as many other objects as possible in as many ways as possible. A game object's handles for interaction need to be globally available and can't impose many invariants—especially if you don't want level designers to have to be constantly re-architecting the engine code to punch new holes for themselves in the API. Thus, a lot of the logic in a given level tends to live inside the callback hooks of level objects, and tends to depend on the state of the rest of the level for correctness.

Modularity is a property of high cohesion and low coupling, which are themselves only possible when you can pin down your design and hide information behind abstraction boundaries. But games are a flexible and dynamic enough field that engines have to basically let designers do whatever they want, whenever they want in order for the engine to be able to build arbitrary games. So game design is naturally a highly-coupled, incohesive problem space that is poorly suited to unit testing.

> So game design is naturally a highly-coupled, incohesive problem space that is poorly suited to unit testing.

Poorly suited? Perhaps, but so are certain web system architectures as well, neither is impossible to test.

I think Factorio is an example that it can be done if you care about it... it's just that most studios shipping games don't.

https://www.factorio.com/blog/post/fff-438

https://www.factorio.com/blog/post/fff-366

Of course, in their case it can actually be justified, because the game itself is very dependent on the logic working correctly, rather than your typical FPS game slop that just needs to look good.

Yeah I suspect Factorio's "complex game logic + simple(ish) 2d engine + minimal team structure" situation meant that the usual tradeoffs didn't apply. It's really cool that they pulled it off, though—I can't imagine it was easy, even then.