IntelliJ IDEA Guide
Get IntelliJ IDEA
Groovy is a powerful, optionally typed and dynamic language for the JVM.
Groovy Tips for Java Developers
(part of tutorial)
Groovy's syntax and functionality might be unusual for Java developers to begin with, but it can be very helpful for testing.
Writing Tests with Spock
Learn about the Spock testing framework by creating a project that uses Spock to unit test Java code