The examples we have just implemented into our projects are very basic, the possibilities with CI/CD are endless.
It is quite common for ATLAS repositories to run tests in their GitLab CI.
One simple thing to try would be to get the GitLab CI to run the CMake tests you hopefully were able to use earlier in the CMake tutorial. Maybe even create your own test
Now that you can compile your code, the next step would be to access the file from cvmfs/eos on GitLab and run your code.
Unfortunately we were unable to make the GitLab runners execute over our test file. However, this is possible! It requires a little bit of setup but if there is time, look into accessing data using GitLab CI. It would either require a CERN service account or letting GitLab CI know your username and password for eos. If you wish to take on this step, let one of the instructors know. Note this may require setting authentication variables
Some resources that might help: