Pest is a testing framework that mimics the syntax of Jest.

It's a wrapper around the PHPUnit test suite with a more fluent syntax.

Installing Pest is simple:

composer require pestphp/pest --dev --with-all-dependencies

Then create a tests folder and run the init command:

./vendor/bin/pest --init

After that you can run Pest with:

./vendor/bin/pest

We are using Pest for unit testing purposes on the Eightshift libs.

Writing tests is really simple. You can use either it or test function

<?php

it('makes sure test works', function() {
    $this->assertTrue(true);
});

This is a trivial example that doesn't actually test anything other than that the test suite is working.

Currently it's only possible to use Pest as unit test suite, for integration testing you're still better off with wp-browser.