Spock is a testing and specification framework for Java and Groovy applications. What makes it stand out from the crowd is its beautiful and highly expressive specification language.

Isolated container management for Java code testing

Akka is a toolkit for building highly concurrent, distributed, and resilient message-driven applications for Java and Scala.

JUnit is a regression testing framework written by Erich Gamma and Kent Beck. It is used by the developer who implements unit tests in Java.

Cucumber JVM: Java 8

XMLUnit for Java

Java DSL for easy testing of REST services

Guava testlib is a set of java classes used for more convenient unit testing - particularly to assist the tests for Guava itself.

Akka is a toolkit for building highly concurrent, distributed, and resilient message-driven applications for Java and Scala.

A set of Hamkrest matchers for common http4k types