The GitLab CI pipelines are configured via a
.gitlab-ci.yml file on the root of your project.
GitLab will read this file and run the defined pipelines for you.
Usually you want to run as much tests as possible.
This is most likely achieved by running all the
make test-* commands in the test stage of the pipeline.
Have a look at the GitLab section and ensure merge requests can not be accepted until the pipeline succeeds. This helps to avoid non-compliant code in the live project.