magento-test/app/code/Magento/Newsletter/Test/Mftf/Data/NewsletterTemplateData.xml

<?xml version="1.0" encoding="UTF-8"?>
<!--
 /**
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
-->

<entities xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:mftf:DataGenerator/etc/dataProfileSchema.xsd">
    <entity name="_defaultNewsletter" type="cms_page">
        <data key="name" unique="suffix">Test Newsletter Template</data>
        <data key="subject">Test Newsletter Subject</data>
        <data key="senderName">Admin</data>
        <data key="senderEmail">admin@magento.com</data>
        <data key="textAreaContent">Some Test Content</data>
    </entity>
    <entity name="updatedNewsletter" type="cms_page">
        <data key="name" unique="suffix">Updated Newsletter Template</data>
        <data key="subject">Updated Newsletter Subject</data>
        <data key="senderName">Admin</data>
        <data key="senderEmail">admin@magento.com</data>
        <data key="textAreaContent">Some Updated Test Content</data>
    </entity>
</entities>