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Comment by marcosdumay | Hacker News Reader

I guess the GP's issue is because automated tests (and every other kind of validation) imposes architectural constraints on your system, and thus are an exception to your rule.

I don't think that rule can be applied as universally as you stated it. But then, I have never seen anybody breaking it in a bad way that did also break it in a good way, so the people that need to hear it will have no problem with the simplified version until they grow a bit.

Anyway, that problem is very general of software development methods. Almost every one of them is contextual. And people start without the maturity to discern the context from the advice, so they tend to overgeneralize what they see.

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Hm. I think maybe you're using "system" to mean a different thing than I am? I thinking of "the system" as the thing that is executing in production - it provides the business behavior we are trying to provide; there is a larger "system" surrounding it, that includes the processes and engineers, and the CI/CD pipelines - it too has an "architecture", and _that_ architecture gets (moderately) more complex when you add CI/CD. Is that where our communication is clashing?

Because the complexity of that outer system is also important, but there are a few very major differences between the two that are probably too obvious to belabor. But in general, architectural complexity in the inner system costs a lot more than it does in the outer system, because it's both higher churn (development practices change much slower than most products) and higher risk (taking production systems offline is much less permissible than freezing deployments)

> I think maybe you're using "system" to mean a different thing than I am?

No, I'm not. Are you overlooking some of the impacts of your tests and most of the impact of static verification?

Those do absolutely impact your system, not only your environment. For tests it's good to keep those impacts at a minimum (for static verification you want to maximize them), but they still have some.

I don't think I'm overlooking any major ones, but we are probably working in quite different types of systems - I'm not aware of any type of static verification I'd use in a rails application that would affect _architecture_ in a meaningful way (unless I would write quite terrifying code without the verifier I suppose).

I'm not sure about the tests - it depends on what you'd consider an impact possibly; I've been trained by my context to design code to be decomposable in a way that _is_ easily testable, but I'm not sure that is really an 'impact of the tests' (and I'm fairly confident that it makes the abstractions less complex instead of more).

Would you mind explaining what you mean in more detail?

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