Book Image

Test-Driven Development with PHP 8

By : Rainier Sarabia
Book Image

Test-Driven Development with PHP 8

By: Rainier Sarabia

Overview of this book

PHP web developers end up building complex enterprise projects without prior experience in test-driven and behavior-driven development which results in software that’s complex and difficult to maintain. This step-by-step guide helps you manage the complexities of large-scale web applications. It takes you through the processes of working on a project, starting from understanding business requirements and translating them into actual maintainable software, to automated deployments. You’ll learn how to break down business requirements into workable and actionable lists using Jira. Using those organized lists of business requirements, you’ll understand how to implement behavior-driven development (BDD) and test-driven development (TDD) to start writing maintainable PHP code. You’ll explore how to use the automated tests to help you stop introducing regressions to an application each time you release code by using continuous integration. By the end of this book, you’ll have learned how to start a PHP project, break down the requirements, build test scenarios and automated tests, and write more testable and maintainable PHP code. By learning these processes, you’ll be able to develop more maintainable, and reliable enterprise PHP applications.
Table of Contents (17 chapters)
Part 1 – Technical Background and Setup
Part 2 – Implementing Test-Driven Development in a PHP Project
Part 3 – Deployment Automation and Monitoring

TDD with the Dependency Inversion Principle

In terms of making a class more testable, the DIP is probably the most important principle on the list for me. The DIP suggests that details should depend on abstractions. To me, this means that the specifics of a program that does not really belong to a class should be abstracted. The DIP allows us as developers to remove a concrete implementation of a routine or program and put it in a different object altogether. We can then use the DIP to inject the object that we need, whenever we need it. We can inject the object that we need in the constructor, passed as an argument upon class instantiation, or simply expose a mutator function.

Let’s revisit the ToyCarValidator class that we created earlier in this chapter to see how we can implement the DIP.

How will this look in our code?

Going back to the ToyCarValidator.php class, you will notice that in the __constructor method, we have instantiated two classes: