Test Arrayable to output readonly

News.php

<?php
use yii\base\Arrayable;
use yii\base\ArrayableTrait;
use yii\base\Component;
use yii\helpers\ArrayHelper;

class News extends Component implements Arrayable
{
    use ArrayableTrait;
    protected $article_title = '';

    public function setTitle($value)
    {
        $this->article_title = strip_tags(htmlspecialchars_decode($value));
        return $this;
    }

    public function getTitle() : string
    {
        return $this->article_title;
    }

    /**
     * @inheritdoc
     */
    public function fields()
    {
        $fields = array_merge(array_keys(\Yii::getObjectVars($this)), ['title']);
        return array_combine($fields, $fields);
    }
}

$news = new Article;
$news->title = 'Test';
var_dump(ArrayHelper::toArray($news));