yii2-save-relations-behavior/tests/models/Company.php

<?php

namespace tests\models;

class Company extends \yii\db\ActiveRecord
{

    /**
     * @inheritdoc
     */
    public static function tableName()
    {
        return 'company';
    }

    /**
     * @inheritdoc
     */
    public function rules()
    {
        return [
            ['name', 'required'],
            ['name', 'unique', 'targetClass' => '\tests\models\Company'],
        ];
    }

}