Today I tried to refactor some code into a swift package from Xcode 11 and set up a CI bot on my Xcode server to test the package. Although I can build and test the swift package locally without problems, the bot can't build at all, with the following error:
Build Service Error: The directory /Users/username/Library/Caches/XCSBuilder/Bots/*snip*/Source does not contain an Xcode project, workspace or package.
I don't think it's a problem with the repository because I can clone it into a fresh directory and build/test locally. I can navigate to that directory on the server and it appears to have the same layout, permissions, etc as other bot directories that work. The only difference is it contains a swift package instead of an Xcode project.
Is this not supported (yet?)
Replying to my own post... I found this article today: https://developer.apple.com/documentation/swift_packages/building_apps_that_use_swift_packages_in_continuous_integration_workflows
So I guess Xcode server can't build swift packages. That's pretty unfortunate but at least now I know so I can stop wasting time troubleshooting.
The error strongly implies that it can build packages ("... does not contain an Xcode project, workspace or package") so hopefully this is coming soon.