magento-test/app/code/Magento/Customer/Test/Mftf/ActionGroup/StorefrontFakeBrokenSessionActionGroup.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="StorefrontFakeBrokenSessionActionGroup">
        <resetCookie userInput="PHPSESSID" stepKey="resetCookieForCart"/>
        <resetCookie userInput="form_key" stepKey="resetCookieForCart2"/>
    </actionGroup>
</actionGroups>