FormTestSubmitButtonAttributeForm.php

<?php

declare (strict_types=1);
namespace Drupal\form_test\Form;

use Drupal\Core\Form\FormBase;
use Drupal\Core\Form\FormStateInterface;

/**
 * Builds a simple form to test the submit_button attribute.
 *
 * @internal
 */
class FormTestSubmitButtonAttributeForm extends FormBase {
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() : string {
        return 'form_test_submit_button_attribute';
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state, $customize = FALSE) : array {
        $form['submit-button-attr'] = [
            '#type' => 'button',
            '#submit_button' => TRUE,
            '#value' => $this->t('Try to Submit'),
        ];
        if ($customize) {
            $form['submit-button-attr'] = [
                '#type' => 'button',
                '#submit_button' => FALSE,
                '#value' => $this->t('Submit if you can'),
            ];
        }
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) : void {
    }

}