<?php
/**
 * Paid invoice fixture.
 *
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */

use Magento\Sales\Api\Data\OrderInterfaceFactory;
use Magento\TestFramework\Helper\Bootstrap;
use Magento\TestFramework\Workaround\Override\Fixture\Resolver;

Resolver::getInstance()->requireDataFixture('Magento/Sales/_files/default_rollback.php');
Resolver::getInstance()->requireDataFixture('Magento/Sales/_files/order.php');

$objectManager = Bootstrap::getObjectManager();
/** @var \Magento\Sales\Model\Order $order */
$order = $objectManager->get(OrderInterfaceFactory::class)->create()->loadByIncrementId('100000001');
$orderService = $objectManager->create(
    \Magento\Sales\Api\InvoiceManagementInterface::class
);
$invoice = $orderService->prepareInvoice($order);
$invoice->register();
$order = $invoice->getOrder();
$order->setIsInProcess(true);
$transactionSave = $objectManager
    ->create(\Magento\Framework\DB\Transaction::class);
$transactionSave->addObject($invoice)->addObject($order)->save();