To properly illustrate continuous integration, we really need a project that meets the following requirements:
Unit tests have been created for all or most of the project
The source code resides in version control repository
Inline documentation has been written to conform to phpDocumentor syntax
There exists a well-defined coding style that can be validated using PHP_CodeSniffer
Creating such a project from scratch is completely out of scope for this chapter, however, there are plenty of open source projects available that will serve perfectly as guinea pigs for our purposes. Since it has repeatedly come up in our discussion of coding style and frameworks, we are going to implement a continuous integration process for the Zend Framework because it satisfies all our requirements above. Besides, it will be nice to get some hard numbers on code coverage and unit test for a development framework that is aiming at wide adoption.