The complete test suite is running on a public GitLab CI. If you are an external contributor, we also have a Travis instance where a small subset of tests is running as well - mostly style and easy fast checks, which are quite common to fail for new contributors.
See this list of CI jobs descriptions for more info.
The CI folder contains all the .yml GitLab files that are included in the main .gitlab.yml to provide some basic structure. All GitLab CI Jobs run inside a docker image, which is built using the present Dockerfile. This image is stored in the GitLab registry.