How to run CI test as non-root user

I’m using a shared runner on GitLab.com.

For my test, the Laravel/composer should not be installed as the root user. (Composer complains anyway).

But the user is always “root”.

I tried to script adding a new user, and then change to the new user with “sudo su - newuser” which executed without errors, but “whoami” afterwards revealed that the script was still running as root.

Is there a way to configure e.g. in the YAML a different user that can run the test sequence?

One question: did you create the runner?

No, this was a Gitlab.com shared runner.