Unclear how to build swift packages on macOS

[schwa]

I have quite a few packages that are swift packages with a Demo directory containing an xcodeproj.

I'd like to make a swift package build job and a separate xcodebuild job for the demo.

It's unclear from documentation how to just run a swift build (there's info on linux but that's not really useful here) and trying to just run this action from project root fails with "no xcodeproject found".

Is there a way to use this just to run swift build/test?

[mxcl]

If there's a Package.swift it will just work. We do this in CI using eg. this fixture directory.

Probs should be documented, but yeah, it should just work. LMK.