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

use Magento\Sales\Model\Order;
use Magento\Sales\Model\Order\Creditmemo;
use Magento\Sales\Model\Order\Creditmemo\Comment;
use Magento\Sales\Model\Order\CreditmemoFactory;
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');

/** @var Order $order */
$order = Bootstrap::getObjectManager()->create(Order::class);
$order->loadByIncrementId('100000001');

/** @var CreditmemoFactory $creditmemoFactory */
$creditmemoFactory = Bootstrap::getObjectManager()->get(CreditmemoFactory::class);

/** @var Creditmemo $creditmemo */
$creditmemo = $creditmemoFactory->createByOrder($order, $order->getData());
$creditmemo->setOrder($order);
$creditmemo->setState(Creditmemo::STATE_OPEN);
$creditmemo->setIncrementId('100000001');
$creditmemo->save();

$comments = [
    [
        'comment' => 'comment 1',
        'is_visible_on_front' => 1,
        'is_customer_notified' => 1,
    ],
    [
        'comment' => 'comment 2',
        'is_visible_on_front' => 1,
        'is_customer_notified' => 1,
    ],
    [
        'comment' => 'comment 3',
        'is_visible_on_front' => 1,
        'is_customer_notified' => 1,
    ],
    [
        'comment' => 'comment 4',
        'is_visible_on_front' => 1,
        'is_customer_notified' => 1,
    ],
    [
        'comment' => 'comment 5',
        'is_visible_on_front' => 0,
        'is_customer_notified' => 1,
    ],
];

foreach ($comments as $data) {
    /** @var $comment Comment */
    $comment = Bootstrap::getObjectManager()->create(Comment::class);
    $comment->setParentId($creditmemo->getId());
    $comment->setComment($data['comment']);
    $comment->setIsVisibleOnFront($data['is_visible_on_front']);
    $comment->setIsCustomerNotified($data['is_customer_notified']);
    $comment->save();
}