PChomePay unit test basic

This document discusses unit testing and provides guidance on writing good unit tests. It defines a unit test as code that invokes a unit of work and checks a specific end result. The document notes that integrating AuthService directly in a test is problematic as it makes the test redundant, brittle to code changes, and difficult for others to understand. It then outlines characteristics of good unit tests, including being automated, repeatable, easy to implement, isolated, and able to pinpoint failures. The document demonstrates writing a first unit test in PHPUnit and covers types of assertions, best practices like the AAA pattern and single assertions, and using setup and teardown methods.