How to do it...

1. First, install the Simpletest module. Even though you might only want to run PHPUnit, this is a soft dependency for running the test runner script.
2. Open a command-line terminal and navigate to your Drupal installation directory.
3. Next, we will run the test runner script. We will pass it a url option so that the Functional tests can run the browser emulator properly. We will also specify the test suites to run. This allows us to skip FunctionalJavascript tests due to PhantomJS not handling concurrency properly in the test runner:

$ php core/scripts/run-tests.sh --url http://localhost--types Simpletest,PHPUnit-Unit,PHPUnit-Kernel,PHPUnit-Functional --concurrency 20 --all

1. Running FunctionalJavascripts tests require PhantomJS to be running. Since PhantomJS prints output to the terminal, open a new tab or terminal and run the following command:

phantomjs --ssl-protocol=any --ignore-ssl-errors=true vendor/jcalderonzumba/gastonjs/src/Client/main.js 8510 1024 768 

1. With PhantomJS running, we can now execute the FunctionalJavascript test suite:

php core/scripts/run-tests.sh --url http://localhost--types PHPUnit-FunctionalJavascript --concurrency 1 --all

1. Review test output from each test suite run.