Captcha Helper method override not working in Magento2

Question

Need to override method getImgUrl() from vendor\magento\module-captcha\Helper\Data.php but not success

app/code/YourCompany/YourModule/etc/di.xml

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
<preference for="Magento\Captcha\Helper\Data" type="YourCompany\YourModule\Helper\Data" />     

Override helper method code

namespace YourCompany\YourModule\Helper;
class Data extends \Magento\Captcha\Helper\Data
{
    public function __construct() {
        echo "Helper Rewrite Working"; die() // working till here
    }


    public function getImgUrl($website = null)
    {
        return $this->_storeManager->getStore()->getBaseUrl(
            DirectoryList::MEDIA
        ) . 'testhelper' . '/' . $this->_getWebsiteCode(
            $website
        ) . '/';
    }
}

Answer 1

Try using plugin:

app/code/SR/MagentoCommunity/etc/di.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="Magento\Captcha\Helper\Data">
        <plugin name="sr_captcha_data"
                type="SR\MagentoCommunity\Plugin\Captcha\Helper\Data" sortOrder="1"/>
    </type>
</config>

app/code/SR/MagentoCommunity/Plugin/Captcha/Helper/Data.php

<?php
namespace SR\MagentoCommunity\Plugin\Captcha\Helper;


class Data
{
    public function afterGetImgUrl(
        \Magento\Captcha\Helper\Data $subject,
        $url
    ) {
        // add your logic

        return $url;
    }
}