FlexUnit has been donated to the Apache Flex project and is now maintained in Apache repositories and via their mailing lists:

https://flex.apache.org/
https://flex.apache.org/community-mailinglists.html

All patches and submissions to FlexUnit must now be handled via Apache.

FlexUnit is a unit testing framework for Flex and ActionScript 3.0 applications and libraries. It mimics the functionality of JUnit, a Java unit testing framework, and comes with a graphical test runner.

Some of FlexUnits features include:

• Support for Flex or ActionScript 3
• Mark tests with Metadata
• Async testing support
• Exception Handling
• Theories, Datapoints and Assumptions

Documentation for FlexUnit can be found at https://cwiki.apache.org/confluence/display/FLEX/FlexUnit+Introduction

The code for FlexUnit can be found on Apache Git