Run jobs only/except when there are modifications on a given path

It would be nice if we could run jobs if there are modifications on paths matching a regex. For instance, if a commit only modifies files in the test subdirectory, only test stage would be run. This is achievable in Jenkins using "included/excluded regions" in Version Control configuration. In the gitlab-ci.yml, we could have something like:

  only:
    - paths:
        - "^test/.*"

For completeness, this should also be supported on except.