magento-test/app/code/Magento/Sales/Test/Mftf/ActionGroup/AssertStorefrontCustomerOrderMatchesGrandTotalActionGroup.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="AssertStorefrontCustomerOrderMatchesGrandTotalActionGroup">
        <annotations>
            <description>Check that order grand total equals sum of all totals.</description>
        </annotations>

        <grabTextFrom selector="{{StorefrontSalesOrderSection.salesOrderPrice('subtotal')}}" stepKey="grabValueForSubtotal"/>
        <grabTextFrom selector="{{StorefrontSalesOrderSection.salesOrderPrice('shipping')}}" stepKey="grabValueForShippingHandling"/>
        <grabTextFrom selector="{{StorefrontSalesOrderSection.salesOrderPrice('grand_total')}}" stepKey="grabValueForGrandTotal"/>
        <executeJS function="
            var grandTotal = '{$grabValueForGrandTotal}'.substr(1);
            return (grandTotal);" stepKey="grandTotalValue"/>
        <executeJS function="
               var subtotal = '{$grabValueForSubtotal}'.substr(1);
               var handling = '{$grabValueForShippingHandling}'.substr(1);
               var subtotalHandling = (parseFloat(subtotal) + parseFloat(handling)).toFixed(2);
               return (subtotalHandling);" stepKey="sumTotalValue"/>
        <assertEquals stepKey="assertSubTotalPrice">
            <expectedResult type="variable">sumTotalValue</expectedResult>
            <actualResult type="variable">grandTotalValue</actualResult>
        </assertEquals>
    </actionGroup>
</actionGroups>