WC_Order::set_billing_phone PHP Method

    public function set_billing_phone($value)
    {
        $this->set_address_prop('phone', 'billing', $value);
    }

 /**
  * Test: get_billing_phone
  */
 function test_get_billing_phone()
 {
     $object = new WC_Order();
     $set_to = '123456678';
     $object->set_billing_phone($set_to);
     $this->assertEquals($set_to, $object->get_billing_phone());
 }