Xtest has a simple Java-like syntax that removes unneccessary boilerplate and adds expressions that make unit testing concepts part of the language.
The Xtext framework provides full Eclipse IDE integration for Xtest including syntax highlighting and auto-complete so that using Xtest feels no different than Java.
Xtest files sit in your Eclipse workspace in a passing or failing state and are only run when a dependency so you are immediately notified of failures.
Xtest is based on Xbase which provide Java integration and some nice additions like type inference, overloaded operators, and lambda expressions to name a few.
Xtest scripts be linked into existing JUnit test suites and can also invoke existing JUnit test suites to be used to alert you when they are failing.
Xtest grants access to private members of Java classes. Think of a probe for testing and tweaking voltages at internal nodes of a circuit board - that is what Xtest allows for Java code without changing its API.