I am still (slowly) working on a Grails tutorial with security and tests. I finally got a few basic Spock controller tests working on a controller that uses the Spring Security plugin.
I am also looking at the plugin for Apache Shiro. It looks like a nice framework that can handle a lot of security needs.
Who knows. I might do two tutorials.
Image from Vienna Coronation Gospels, an 8th Century Carolingian manuscript housed at the Imperial Treasury in Vienna. Image from Wikimedia, assumed allowed under Fair Use.