WC_Order::get_total_tax_refunded_by_rate_id PHP Method

    public function get_total_tax_refunded_by_rate_id($rate_id)
    {
        $total = 0;
        foreach ($this->get_refunds() as $refund) {
            foreach ($refund->get_items('tax') as $refunded_item) {
                if (absint($refunded_item->get_rate_id()) === $rate_id) {
                    $total += abs($refunded_item->get_tax_total()) + abs($refunded_item->get_shipping_tax_total());
                }
            }
        }
        return $total;
    }

 /**
  * Test: get_total_tax_refunded_by_rate_id
  */
 function test_get_total_tax_refunded_by_rate_id()
 {
     $object = new WC_Order();
     $this->assertEquals(0, $object->get_total_tax_refunded_by_rate_id(2));
 }