Working with popup and Behat/Mink Behat3

Popup.php

<?php

use Behat\MinkExtension\Context\RawMinkContext;

/**
 * Add Popup in Context
 */
class Popup extends RawMinkContext
{
    /**
     * @when /^(?:|I )confirm the popup$/
     */
    public function confirmPopup()
    {
        $this->getSession()->getDriver()->getWebDriverSession()->accept_alert();
    }

    /**
     * @when /^(?:|I )cancel the popup$/
     */
    public function cancelPopup()
    {
        $this->getSession()->getDriver()->getWebDriverSession()->dismiss_alert();
    }

    /**
     * @When /^(?:|I )should see "([^"]*)" in popup$/
     *
     * @param string $message The message.
     */
    public function assertPopupMessage($message)
    {
        $alertText = $this->getSession()->getDriver()->getWebDriverSession()->getAlert_text();
        if ($alertText !== $message){
            throw new Exception("Modal dialog present: $alertText, when expected was $message");
        }   
    }

    /**
     * @When /^(?:|I )fill "([^"]*)" in popup$/
     *
     * @param string $message The message.
     */
    public function setPopupText($message)
    {
        $this->getSession()->getDriver()->getWebDriverSession()->postAlert_text($message);
    }
}