We've developed a SAML2 SP (supporting IdP-Initiated SSO, as per the user journey we want).
My question is, short of developing an IdP, how can we test it is working? Is there an IdP-Initiated SSO test harness out there? (I know of SSO Circle, but that is for SP-Initiated SSO).
You can use a trial account from Onelogin and configure a SAML Test Connector, or deploy your own IdP with simpleSAMLphp