Once you have registered your IdP, you can test your IdP configuration using this UK federation test service provider:
The index page contains a number of links, which invoke different versions of the Discovery Service. The links marked as "full" have a list of all federation IdPs, including those that have been registered as hidden or invisible. If you click one of these links and select your IdP from the WAYF or DS page and successfully authenticate, you should see a list of environment variables, some of which contain the values of attributes released by the IdP; this allows you to test attribute generation and release as well as simple authentication.
WAYF links use the federation WAYF and will invoke a SAML1 session, which produces two displayed assertions – one for the authentication, one for the attributes. DS links use the federation Discovery Service and may invoke a SAML2 session, which produces a single displayed assertion.
If you are testing a Shibboleth IdP, and you have trouble authenticating or releasing attributes, then ensure your log levels are turned up to DEBUG before re-testing, and check the logs; the idp-process.log is generally the most informative. If nothing is being written to the Shibboleth logs then check the Tomcat or Jetty logs; it is advisable to keep checking the Tomcat or Jetty logs anyway during the earlier stages of the installation.
You should not attempt to gain access to any live service until you have verified, by the use of the test page noted above, that your IdP is properly configured and releasing attributes correctly.