Updated Drupal to 8.6. This goes with the following updates because it's possible...

[yaffs-website] / vendor / phpunit / phpunit / tests / _files / CoverageNoneTest.php

<?php
class CoverageNoneTest extends PHPUnit_Framework_TestCase
{
    public function testSomething()
    {
        $o = new CoveredClass;
        $o->publicMethod();
    }
}