magento-test/app/code/Magento/Customer/etc/mview.xml

<?xml version="1.0" encoding="UTF-8"?>
<!--
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Mview/etc/mview.xsd">
    <view id="customer_dummy" class="Magento\Framework\Indexer\Action\Dummy" group="indexer"/>
</config>