Starting a PHP built in server in phpunit tests

BackgroundProcess.php

<?php

namespace Zalas\Test;

use Symfony\Component\Process\Process;

trait BackgroundProcess
{
    /**
     * @var Process
     */
    private static $process;

    /**
     * @beforeClass
     */
    public static function startBackgroundProcess()
    {
        self::$process = new Process(self::getCommand());
        self::$process->start();
    }

    /**
     * @beforeClass
     */
    public static function verifyBackgroundProcessStarted()
    {
        if (!self::$process->isRunning()) {
            throw new \RuntimeException(sprintf(
                'Failed to start "%s" in background: %s',
                self::$process->getCommandLine(),
                self::$process->getErrorOutput()
            ));
        }
    }

    /**
     * @afterClass
     */
    public static function stopBackgroundProcess()
    {
        self::$process->stop();
    }

    /**
     * @after
     */
    public function clearBackgroundProcessOutput()
    {
        self::$process->clearOutput();
        self::$process->clearErrorOutput();
    }

    /**
     * Returns a command to run in background.
     *
     * @return string
     */
    abstract protected static function getCommand();
}

PhpServer.php

<?php

namespace Zalas\Test;

trait PhpServerProcess
{
    use BackgroundProcess;

    protected static function getCommand()
    {
        return self::getPhpServerCommand();
    }

    protected static function getPhpServerCommand()
    {
        $rootDir = self::getPhpServerOption('root_dir');
        $router = self::getPhpServerOption('router');
        $host = self::getPhpServerOption('host', 'localhost');
        $port = self::getPhpServerOption('port', 8000);

        return sprintf(
            'php -S %s:%d%s%s',
            $host,
            $port,
            $rootDir ? ' -t '.$rootDir : '',
            $router ? ' '.$router : ''
        );
    }

    protected static function getPhpServerOptions()
    {
        return [
            'host' => 'localhost',
            'port' => 8000,
            'root_dir' => null,
            'router' => null
        ];
    }

    private static function getPhpServerOption($option, $default = null)
    {
        $options = self::getPhpServerOptions();

        return array_key_exists($option, $options) ? $options[$option] : $default;
    }
}