PHPUnit

PHPUnit is a representative of unit testing frameworks, whose overall idea is to provide a strict contract over an isolated piece of code that must be satisfied. This piece of code is what we call unit, which translates to the class and its methods in PHP. Using the assertions functionality, the PHPUnit framework verifies that these units behave as expected. The benefit of unit testing is that its early problem detection helps mitigate compound or down-the-line errors that might not be obvious initially. The more possible paths of a program the unit test covers, the better.

Setting up the PHPUnit

PHPUnit can be installed as, provisionally named, a tool or a library. Both are the same things actually, just differing in a way we install and use them. The tool version is really just a PHP phar archive we can run via console, which then provides a set of console commands we can execute globally. The library version on the other hand is a set of PHPUnit libraries packed as a Composer package...