Phinx: Run migration from inside PHP script

gistfile1.php

use Phinx\Config\Config;
use Phinx\Migration\Manager;
use Symfony\Component\Console\Output\NullOutput;

$migrationspath = 'path/to/migrations/folder';

$config = new Config(array(
    'paths' => array(
        'migrations' => $migrationspath
    ),
    'environments' => array(
        'testing' => array(
            'adapter' => 'sqlite',
            'memory' => true
        )
    )
));

$output = new NullOutput();
$manager = new Manager($config, $output);
$manager->migrate('testing');