Recommended project_urls key for travis links?

The setuptools.setup function supports a project_urls option which takes a dict with (AFAIK) arbitrary keys, but some keys are recognised by PyPI:

  • Source is used for the sources URL, typically on Github, and decorated by PyPI with a Github icon;
  • Documentation is the PyPI page (in simple cases) and decorated with a book icon;
  • Tracker is the bugtracker URL and decorated with a bug icon.

Now, it might be useful to add the Travis CI links there as well, e.g. using the key Tests.
Is there some key like this or another in use for this purpose?

The Tests key seems to be supported by PyPI; see e.g. my package ("Project links" in the left column).

Does anyone know about an "official list"?