magento-test/app/code/Magento/SalesRule/Test/Mftf/ActionGroup/StorefrontApplyCouponActionGroup.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">
    <!-- Apply Sales Rule Coupon to the cart -->
    <actionGroup name="StorefrontApplyCouponActionGroup">
        <annotations>
            <description>Applies the provided Coupon Code to the Storefront Shopping Cart.</description>
        </annotations>
        <arguments>
            <argument name="coupon"/>
        </arguments>

        <waitForElement selector="{{StorefrontSalesRuleCartCouponSection.couponHeader}}" time="30" stepKey="waitForCouponHeader"/>
        <conditionalClick selector="{{StorefrontSalesRuleCartCouponSection.couponHeader}}" dependentSelector="{{StorefrontSalesRuleCartCouponSection.discountBlockActive}}" visible="false" stepKey="clickCouponHeader"/>
        <waitForElementVisible selector="{{StorefrontSalesRuleCartCouponSection.couponField}}" stepKey="waitForCouponField"/>
        <fillField userInput="{{coupon.code}}" selector="{{StorefrontSalesRuleCartCouponSection.couponField}}" stepKey="fillCouponField"/>
        <click selector="{{StorefrontSalesRuleCartCouponSection.applyButton}}" stepKey="clickApplyButton"/>
        <waitForPageLoad stepKey="waitForPageLoad"/>
    </actionGroup>
</actionGroups>