I'm currently working as a part of an open source game dev group with most of our work put on Github, and we recently decided to split up a lot of our common code dependencies into git submodules (due to the general lack of a proper user-facing package management system).

Up until now, we utilized Unity Cloud Build to run tests and build all of our dependencies, which were hard-included into the main game repository. However, setting up Unity Cloud Build for each of those small packages is both overkill, would likely eat up our allotted concurrent builds, and would require restructuring all of our packages.

Is there an effective way to compile and test C# code in continuous integration systems like TravisCI, CircleCI, etc? I've tried TravisCI and installing the Linux Editor in batch mode, but it still asks for a Unity login/license on launch, something I'm not comfortable setting up on a third-party CI system.