silverstripe-framework/tests/php/Security/MemberTest/ViewingDeniedExtension.php

<?php

namespace SilverStripe\Security\Tests\MemberTest;

use SilverStripe\Dev\TestOnly;
use SilverStripe\ORM\DataExtension;

class ViewingDeniedExtension extends DataExtension implements TestOnly
{

    public function canView($member = null)
    {
        return false;
    }
}