magento-test/app/code/Magento/Checkout/Test/Mftf/ActionGroup/StorefrontFillEmailFieldOnCheckoutActionGroup.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="StorefrontFillEmailFieldOnCheckoutActionGroup">
        <annotations>
            <description>Fills in the provided Email Address on the Storefront Checkout page. Double clicks on the Email tooltip.</description>
        </annotations>
        <arguments>
            <argument name="email" type="string"/>
        </arguments>

        <fillField selector="{{StorefrontCheckoutCheckoutCustomerLoginSection.email}}" userInput="{{email}}" stepKey="fillCustomerEmailField"/>
        <doubleClick selector="{{StorefrontCheckoutCheckoutCustomerLoginSection.emailTooltipButton}}" stepKey="clickToMoveFocusFromEmailInput"/>
        <waitForPageLoad stepKey="waitForPageLoad"/>
    </actionGroup>
</actionGroups>