One of my super short reviews on the books I read in my My Way to PHP series.
PHPUnit Essentials By Zdenek Machek
This is a short book about PHPUnit. It covers everything from the installation to testing databases. There are chapters on other testing tools like Behat, Selenium and CI. 
The chapters about PHPUnit are readable and they cover the essential. It very practical and a short read. If you never had experience with PHPUnit you’ll get enough to integrate it into your workflow.
The book does what it promises. It’s a rather solid book.