Unit testing with PHPUnit

PHPUnit is the most popular PHP testing framework. It is simple for configuration and usage. Also, the framework supports code coverage reports and has a lot of additional plugins. Codeception from the previous recipe uses PHPUnit for own work and writing unit tests. In this recipe, we will create a demonstration shopping cart extension with PHPUnit tests.

Getting ready

Create a new yii2-app-basic application using the Composer package manager, as described in the official guide at http://www.yiiframework.com/doc-2.0/guidestart-installation.html.

How to do it…

First, we must create a new empty directory for own extension.

Preparing extension structure

1. First, create the directory structure for your extension:

   book
   └── cart
       ├── src
       └── tests

   To work with the extension as a Composer package, prepare the book/cart/composer.json file like this:

   {
       "name": "book/cart",
       &quot...