The first of the tools we will introduce is Behat. Behat is a PHP framework that can transform behavioral scenarios into acceptance tests and then run them, providing feedback similar to PHPUnit. The idea is to match each of the steps in English with the scenarios in a PHP function that performs some action or asserts some results.

In this section, we will try to add some acceptance tests to our application. The application will be a simple database migration script that will allow us to keep track of the changes that we will add to our schema. The idea is that each time that you want to change your database, you will write the changes on a migration file and then execute the script. The application will check what was the last migration executed and will perform new ones. We will first write the acceptance tests and then introduce the code progressively as BDD suggests.

In order to install Behat on your development environment, you can use Composer. The command is as follows...