Programming

I don’t think you really have a choice TBH. Trying to do something like that sounds like a world of pain, and a bunch of unidiomatic code. If you can’t actually support 4 to 10 languages, maybe you should cut back on which ones you support?

To be clear, the SDKs themselves are hand-written; I'm not trying to do anything fancy there. In terms of designing and writing the SDKs, we can manage that for the 4 we have now. The issue is testing. The main system is a collection of services that are accessed via an API. That API can be accessed directly through function calls, or via HTTP or RPC. Our integration tests interact with the system through that API. The SDKs have a moderate amount of logic so they're not simple HTTP/RPC clients, but maintaining multiple (idiomatic) versions of that logic is not too much of a burden. The issue is that I want a single test corpus that I can use to validate each SDK without having to rewrite that test corpus in each language. Ideally I'd like the integration tests to be that test corpus.

If neither of those approaches works, everything speaks C FFI, and Rust is a modern language that would work well for presenting a C FFI that the other languages can use. You’re probably not hot on the idea of rewriting your Go tests into another language, but I think that’s your only real option then.

I was assuming I'd need to rewrite my tests in Go given that Go's FFI support for anything other than C is not somewhere I want to go again. I have been meaning to learn Rust so I might just do that.

Yeah, that's pretty much what I was thinking too. The combination of a c API and a JVM API (and maybe .NET if you're in Microsoft land?) Hits most FFI available in languages I've seen. I can't think of any language I've used that couldn't Interop with either a c library (.a or .so) or JVM library (.jar). However I've never used any .NET system seriously, so I don't know about them.

FWIW I regularly remake the same API based game whenever I start a new job working in a new environment to test that my environment is "up to snuff" with my development methodologies. I've never needed to port more than API.a and API.jar to play around in any language. I've ported that system to at least 100 languages over the years, and while some have more friction than others, and often the c/JVM paradigm doesn't line up well with the target language, it is always effective.