#[derive(Debug)] struct Package { sender_country: String, recipient_country: String, weight_in_grams: u32, } impl Package { fn new(sender_country: String, recipient_country: String, weight_in_grams: u32) -> Self { if weight_in_grams < 10 { // This isn't how you should handle errors in Rust, but we will // learn about error handling later. panic!("Can't ship a package with weight below 10 grams"); } Self { sender_country, recipient_country, weight_in_grams, } } fn is_international(&self) -> bool { // ^^^^^^^ added self.sender_country != self.recipient_country } fn get_fees(&self, cents_per_gram: u32) -> u32 { // ^^^^^^ added self.weight_in_grams * cents_per_gram } } fn main() { // You can optionally experiment here. } #[cfg(test)] mod tests { use super::*; #[test] #[should_panic] fn fail_creating_weightless_package() { let sender_country = String::from("Spain"); let recipient_country = String::from("Austria"); Package::new(sender_country, recipient_country, 5); } #[test] fn create_international_package() { let sender_country = String::from("Spain"); let recipient_country = String::from("Russia"); let package = Package::new(sender_country, recipient_country, 1200); assert!(package.is_international()); } #[test] fn create_local_package() { let sender_country = String::from("Canada"); let recipient_country = sender_country.clone(); let package = Package::new(sender_country, recipient_country, 1200); assert!(!package.is_international()); } #[test] fn calculate_transport_fees() { let sender_country = String::from("Spain"); let recipient_country = String::from("Spain"); let cents_per_gram = 3; let package = Package::new(sender_country, recipient_country, 1500); assert_eq!(package.get_fees(cents_per_gram), 4500); assert_eq!(package.get_fees(cents_per_gram * 2), 9000); } }