The test federation available from the federation registry allows you testing the installation, configuration and operation of your IdP and/or SP components.
It does not host any production services, and no guarantee is given on its availability or sustainability.

Anyone is free to declare an identity provider or service provider, without prior authorization or paper documents, while doing so online through the federation registry.

The metadata of the test federation can be downloaded from the metadata page.

RENATER offers a WAYF listing all identity providers of the test federation: https://discovery.renater.fr/test