Guava is a suite of core and expanded libraries that include

Utilities for serializing and de-serializing tasks and their additionalInformation

Java DSL for easy testing of REST services

JUnit Jupiter is the API for writing tests using JUnit 5.

JSON Assertions based on AssertJ

Apache James Mailet Test is a collection of utilities to help testing mailets.

Rich and fluent assertions for testing in Java

Core API and libraries of hamcrest matcher framework.

Core package for the JUnit Jupiter test engine.

JUnit Jupiter extension for running parameterized tests.

Public API for configuring and launching test plans.

Mockito mock objects library core API and implementation