magento-test/app/code/Magento/Sales/Test/Mftf/ActionGroup/AdminFillQtyToInvoiceOnCreateInvoicePageActionGroup.xml

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

<actionGroups xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:mftf:Test/etc/actionGroupSchema.xsd">
    <actionGroup name="AdminFillQtyToInvoiceOnCreateInvoicePageActionGroup">
        <annotations>
            <description>Fills the "Qty to invoice" field on the Create Invoice page</description>
        </annotations>
        <arguments>
            <argument name="qty" type="string" defaultValue="1"/>
        </arguments>

        <fillField selector="{{AdminOrderInvoiceViewSection.invoiceQty}}" userInput="{{qty}}" stepKey="fillQtyToInvoiceField"/>
    </actionGroup>
</actionGroups>