atk4\data\tests\ReferenceSQLTest::testLink PHP Method

    public function testLink()
    {
        $db = new Persistence_SQL($this->db->connection);
        $u = (new Model($db, 'user'))->addFields(['name']);
        $o = (new Model($db, 'order'))->addFields(['amount', 'user_id']);
        $u->hasMany('Orders', $o);
        $this->assertEquals('select `id`,`amount`,`user_id` from `order` where `user_id` = `user`.`id`', $u->refLink('Orders')->action('select')->render());
    }