Constraints validation is one of the coolest features of Grails. You can apply them to Domain classes, command objects, URL Mappings. This week we published a Grails Guide focused on domain class constraints testing.
When you pass a list of Strings to the validate method, the validate method will only validate the properties you pass. A domain class may have many properties. This allows you to tests properties validation on isolation.
I entered @jackfrosch's workshop at Greach a bit intimidated. He promised to create a microservices federation with two Grails apps plus Eureka, Hystrix, Zuul. I had no experience with any of the Netflix Open Source technologies. Thus, I was not sure to be able to follow the workshop.
However, Jack is a wonderful presenter. He presented all the pieces involved and layout the knowledge to complete a Step-By-Step Asciidoc Repository with the workshop.