Changing the value of zoho.loginuser

Changing the value of zoho.loginuser

For testing purposes, it would be great if a developer of an app could change the value of zoho.loginuser.  I've written an app that behaves differently depending upon who the user is.  For testing, I have to login as each person to verify their roles.  It would be better if I could simply change the value of zoho.loginuser and effectively become that other user without logging out and back in so frequently.