What is the difference between PhpUnit and PhpRack?

I know they both are for testing but I did not find much information about P开发者_运维知识库hpRack here. Can we use them together in a project? Or only one can serve the purpose?

---

PHPUnit is a unit testing framework. Unit testing considers the testing of software from the perspective of discreet units of code, such as a class or method.

PHPRack is an integration testing framework. Integration testing considers the testing of how separate software modules/systems integrate together in a production environment.

Unit testing and integration testing are not the same thing. A development environment can use both.