AssertHelperTrait.php

<?php

namespace Drupal\Tests;

use Drupal\Component\Render\MarkupInterface;

/**
 * Provides helper methods for assertions.
 */
trait AssertHelperTrait {
    
    /**
     * Casts MarkupInterface objects into strings.
     *
     * @param string|array $value
     *   The value to act on.
     *
     * @return mixed
     *   The input value, with MarkupInterface objects casted to string.
     */
    protected static function castSafeStrings($value) {
        if ($value instanceof MarkupInterface) {
            $value = (string) $value;
        }
        if (is_array($value)) {
            array_walk_recursive($value, function (&$item) {
                if ($item instanceof MarkupInterface) {
                    $item = (string) $item;
                }
            });
        }
        return $value;
    }

}