Deal with AJAX block in web-crawler or create manu

Based on Alvin Bunk article link to article I want to create a web-cralwer that logins in a website then submits a form.

My problem is that on that website there is an Ajax block that generates after clicking and empty link few inputs that I need to fill so I need to click that empty link somehow or to insert the inputs manually .

I changed the code below in a lot of ways to try to make it work but on the visit function I got stuck

I get Uncaught Error: Call to a member function visit() on null

<?php
 require 'vendor/autoload.php';

trait MinkSetup
{
    private $minkBaseUrl;
    private $minkSession;

    /**
     * @before
     */
    public function setupMinkSession()
    {
        $this->minkBaseUrl = 'https://www.url.com';
        $driver = new \Behat\Mink\Driver\Selenium2Driver('firefox');
        $this->minkSession = new \Behat\Mink\Session($driver);
        $this->minkSession->start();
    }

    public function getCurrentPage()
    {
        return $this->minkSession->getPage();
    }

    public function getCurrentPageContent()
    {
        return $this->getCurrentPage()->getContent();
    }

    public function visit($url)
    {
         echo $url;
        $this->minkSession->visit($url);
    }

    public function login($user, $pass){
        $this->minkSession->visit('complete url');
        $page = $this->getCurrentPage();
        echo $page;
        $page->fillField('email', $user); // Enter username.
        $page->fillField('password', $pass); // Enter password.
        $page->pressButton('Login');

        $content = $this->getCurrentPageContent();
        $this->assertContains('logout', $content);
    }

    /**
     * @afterClass
     */
    public function logout(){
        $page = $this->getCurrentPage();
        $page->clickLink('logout');
    }
}
use PHPUnit\Framework\TestCase;


class MinkPetitionTest extends  TestCase
{
    use MinkSetup;

    public function testSubmitPage(){
        $this->login('user', 'pw'); // Login first.

        $this->visit('full url');
        $page = $this->getCurrentPage(); // Get the page.
        echo $page;
        $page->fillField('form_ban_id', '1234');
        $page->pressButton('form_find_student');

        $content = $this->getCurrentPageContent();   // Get page content.
        $this->assertContains('<u>No Petitions</u> exist for Some User Student ID: 1234', $content);
    }
}



$client = new MinkPetitionTest(); //tried to get something to work
$client->testSubmitPage(); //same here

You need to change your test class like so if you are using the latest phpunit:

...
use PHPUnit\Framework\TestCase;

class MinkPetitionTest extends TestCase
{
   ...

Can you try that first and see the result?

EDIT #2

Also, your trait file is incorrect. it should be:

trait MinkSetup
{
    private $minkBaseUrl;
    ...

    public function visit($url)
    {
        $this->minkSession->visit($this->minkBaseUrl . $url);
    }
    ...

Try that