magento-test/app/code/Magento/Ui/Test/Mftf/Section/StorefrontMessagesSection.xml

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

<sections xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:mftf:Page/etc/SectionObject.xsd">
    <section name="StorefrontMessagesSection">
        <element name="success" type="text" selector="div.message-success.success.message"/>
        <element name="error" type="text" selector="div.message-error.error.message"/>
        <element name="noticeMessage" type="text" selector="div.message.notice div"/>
        <element name="messageByType" type="text" selector=".messages .message-{{messageType}}" parameterized="true" />
    </section>
</sections>