Mockery : Mockery is a simple yet flexible PHP mock object framework for use in unit testing with PHPUnit, PHPSpec or any other testing framework. Its core goal...
vfsStream : vfsStream is a stream wrapper for a virtual file system that may be helpful in unit tests to mock the real file system. It can be used with any unit t...
Idiorm and Paris : A minimalist database toolkit for PHP5.
Object relational mapper (ORM), fluent SQL query builder and Active Record implementation for PHP.
Ratchet : WebSockets for PHP
Ratchet is a loosely coupled PHP library providing developers with tools to create real time, bi-directional applications between c...
Swift Mailer : Swift Mailer integrates into any web app written in PHP 5, offering a flexible and elegant object-oriented approach to sending emails with a multitude...
PHPUnit is the de-facto standard for unit testing in PHP projects. It provides both a framework that makes the writing of tests easy as well as the functionality to easily run the tests and analyse their results.