FormElementLabelTest.php

<?php

namespace Drupal\Tests\system\Kernel\Form;

use Drupal\KernelTests\KernelTestBase;
use Symfony\Component\CssSelector\CssSelectorConverter;

/**
 * Tests for form_element_label theme hook.
 *
 * @group Form
 */
class FormElementLabelTest extends KernelTestBase {
    
    /**
     * {@inheritdoc}
     */
    public static $modules = [
        'system',
    ];
    
    /**
     * Ensures that attributes can be placed for form element label.
     */
    public function testAttributes() {
        $render_array = [
            '#type' => 'label',
            '#attributes' => [
                'class' => [
                    'kitten',
                ],
            ],
            '#title' => 'Kittens',
            '#title_display' => 'above',
        ];
        $css_selector_converter = new CssSelectorConverter();
        $this->render($render_array);
        $elements = $this->xpath($css_selector_converter->toXPath('.kitten'));
        $this->assertCount(1, $elements);
        // Add label attributes to a form element.
        $render_array = [
            '#type' => 'textfield',
            '#label_attributes' => [
                'class' => [
                    'meow',
                ],
            ],
            '#title' => 'Kitten sounds',
        ];
        $this->render($render_array);
        $elements = $this->xpath($css_selector_converter->toXPath('label.meow'));
        $this->assertCount(1, $elements);
    }

}