Drupal 8 uses PHPUnit as the testing framework for all types of tests. In this section, we will see how we can work with it to run tests.
On your development environment (or wherever you want to run the tests), make sure you have the composer dependencies installed with the --dev flag. This will include PHPUnit. Keep in mind not to ever do this on your production environment as you can compromise the security of your application.
Although Drupal has a UI for running tests, PHPUnit is not well integrated with this. So, it's recommended that we run them using the command line instead. Actually, it's very easy to do so. To run the entire test suite (of a certain type), we have to navigate to the Drupal core folder:
cd core
And run the following command:
../vendor/bin/phpunit —testsuite=unit
This command goes back a folder through the vendor directory...