SP require attributes

[Andy Thompson]

I'm working on setting up a native SP to authenticate against a native IDP.  In my testing with setting up attribute filters and such I've found that if the IDP doesn't return attributes to the SP, the authentication is still successful and a session is still established successfully.  To protect against mis configuration how can I configure the SP to not establish a session if there are no attributes returned for the authenticating user?

thanks

-andy