magento-test/app/code/Magento/Sales/Test/Mftf/Section/AdminOrderInvoiceViewSection.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="AdminOrderInvoiceViewSection">
        <element name="invoiceQty" type="input" selector=".input-text.admin__control-text.qty-input" timeout="30"/>
        <element name="updateInvoiceBtn" type="button" selector=".update-button" timeout="30"/>
    </section>
</sections>