app/bundles/LeadBundle/Tests/Controller/FieldControllerTest.php

<?php

namespace Mautic\LeadBundle\Tests\Controller;

use Mautic\CoreBundle\Test\MauticMysqlTestCase;
use Mautic\LeadBundle\Entity\LeadField;
use Symfony\Component\HttpFoundation\Request;

class FieldControllerTest extends MauticMysqlTestCase
{
    protected $useCleanupRollback = false;

    public function testLengthValidationOnLabelFieldWhenAddingCustomFieldFailure(): void
    {
        $crawler = $this->client->request(Request::METHOD_GET, '/s/contacts/fields/new');

        $form  = $crawler->selectButton('Save & Close')->form();
        $label = 'The leading Drupal Cloud platform to securely develop, deliver, and run websites, applications, and content. Top-of-the-line hosting options are paired with automated testing and development tools. Documentation is also included for the following components';
        $form['leadfield[label]']->setValue($label);
        $crawler = $this->client->submit($form);

        $labelErrorMessage             = trim($crawler->filter('#leadfield_label')->nextAll()->text());
        $maxLengthErrorMessageTemplate = 'Label value cannot be longer than 191 characters';

        $this->assertEquals($maxLengthErrorMessageTemplate, $labelErrorMessage);
    }

    public function testLengthValidationOnLabelFieldWhenAddingCustomFieldSuccess(): void
    {
        $crawler = $this->client->request(Request::METHOD_GET, '/s/contacts/fields/new');

        $form  = $crawler->selectButton('Save & Close')->form();
        $label = 'Test value for custom field 4';
        $form['leadfield[label]']->setValue($label);
        $crawler = $this->client->submit($form);

        $field = $this->em->getRepository(LeadField::class)->findOneBy(['label' => $label]);
        $this->assertNotNull($field);
    }
}