FormTestEmptySelectForm.php

<?php

namespace Drupal\form_test\Form;

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

/**
 * Builds a form to test select elements when #options is not an array.
 *
 * @internal
 */
class FormTestEmptySelectForm extends FormBase {
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() {
        return 'form_test_empty_select';
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state) {
        $form['empty_select'] = [
            '#type' => 'select',
            '#title' => t('Empty Select'),
            '#multiple' => FALSE,
            '#options' => NULL,
        ];
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
    }

}