Zumba Engineering Blog: Mocking Singleton PHP classes with PHPUnit

On the Zumba Engineering blog today Chris Taylor has a new post about mocking in PHPUnit, specifically how to handle those pesky Singleton methods lurking around your codebase.

In many of our projects, utilities and vendor classes are implemented with a singleton pattern. [...] In this post, we'll cover a nice way to inject a PHPUnit mock object for use in testing methods that utilize singleton classes.

He starts by introducing mocking and how to use mock classes in PHPUnit with a simple "sayHello" example. Adding on another layer, he creates a "SomeclassMock" class, defining its own "expects" and "cleanup" methods. This class forces the Singleton method to act more like a regular non-static method and "resets" it after each use.