class ElementValidationTest

class ElementValidationTest extends WebDriverTestBase {
    
    /**
     * {@inheritdoc}
     */
    protected static $modules = [
        'ajax_test',
        'ajax_forms_test',
    ];
    
    /**
     * {@inheritdoc}
     */
    protected $defaultTheme = 'starterkit_theme';
    
    /**
     * Tries to post an Ajax change to a form that has a validated element.
     *
     * Drupal AJAX commands update the DOM echoing back the validated values in
     * the form of messages that appear on the page.
     */
    public function testAjaxElementValidation() {
        $this->drupalGet('ajax_validation_test');
        $page = $this->getSession()
            ->getPage();
        $assert = $this->assertSession();
        // Partially complete the form with a string.
        $page->fillField('drivertext', 'some dumb text');
        // Move focus away from this field to trigger AJAX.
        $page->findField('spare_required_field')
            ->focus();
        // When the AJAX command updates the DOM a <ul> unsorted list
        // "message__list" structure will appear on the page echoing back the
        // "some dumb text" message.
        $placeholder_text = $assert->waitForElement('css', "ul.messages__list li.messages__item em:contains('some dumb text')");
        $this->assertNotNull($placeholder_text, 'A callback successfully echoed back a string.');
        $this->drupalGet('ajax_validation_test');
        // Partially complete the form with a number.
        $page->fillField('drivernumber', '12345');
        $page->findField('spare_required_field')
            ->focus();
        // The AJAX request/response will complete successfully when an
        // InsertCommand injects a message with a placeholder element into the DOM
        // with the submitted number.
        $placeholder_number = $assert->waitForElement('css', "ul.messages__list li.messages__item em:contains('12345')");
        $this->assertNotNull($placeholder_number, 'A callback successfully echoed back a number.');
    }

}