silverstripe-frameworktest/code/TestRegistryPage.php

<?php

use SilverStripe\FrameworkTest\Model\TestPage;
use SilverStripe\ORM\DataObject;
use SilverStripe\Registry\RegistryPage;
use SilverStripe\Security\DefaultAdminService;
use SilverStripe\Security\Member;

if (!class_exists(RegistryPage::class)) {
    return;
}

class TestRegistryPage extends RegistryPage
{
    public function requireDefaultRecords()
    {
        if (!DataObject::get_one(static::class)) {
            // Try to create common parent
            $defaultAdminService = DefaultAdminService::singleton();
            Member::actAs($defaultAdminService->findOrCreateDefaultAdmin(), function () {
                $page = new static;
                $page->Title = 'Registry Test Page';
                $page->ShowInMenus = 0;
                $parent = TestPage::getOrCreateParentPage();
                $page->ParentID = $parent->ID;
                $page->DataClass = TestRegistryDataObject::class;
                $page->write();
                $page->publish('Stage', 'Live');
            });
        }
    }
}