SOAP::Transport::LOOPBACK is a test transport backend for SOAP::Lite.
It just returns the XML request as response, thus allowing to test the
complete application stack of client applications from the front end down to
the transport layer without actually sending data over the wire.
Using this transport backend is triggered by setting a loopback:// URL.
Sending requests through this transport backend alway succeeds with the
status: 200 OK