<?php
$data = [
    'pages' => [
        'NEWpage23' => [
            'pid'    => 3,
            'title'  => 'Testpage',
            'hidden' => 0,
            'media'  => 'NEWref42',
        ],
    ],
    'sys_file_reference' => [
        'NEWref42' => [
            'uid_local'   => 'sys_file_21',
            'pid'         => 'NEWpage23',
        ],
    ],
];

$this->dataHandler->start($data, []);
$this->dataHandler->process_datamap();