131 lines
3.3 KiB
Rust
131 lines
3.3 KiB
Rust
// The `From` trait is used for value-to-value conversions. If `From` is
|
|
// implemented, an implementation of `Into` is automatically provided.
|
|
// You can read more about it in the documentation:
|
|
// https://doc.rust-lang.org/std/convert/trait.From.html
|
|
|
|
#[derive(Debug)]
|
|
struct Person {
|
|
name: String,
|
|
age: u8,
|
|
}
|
|
|
|
// We implement the Default trait to use it as a fallback when the provided
|
|
// string is not convertible into a `Person` object.
|
|
impl Default for Person {
|
|
fn default() -> Self {
|
|
Self {
|
|
name: String::from("John"),
|
|
age: 30,
|
|
}
|
|
}
|
|
}
|
|
|
|
// TODO: Complete this `From` implementation to be able to parse a `Person`
|
|
// out of a string in the form of "Mark,20".
|
|
// Note that you'll need to parse the age component into a `u8` with something
|
|
// like `"4".parse::<u8>()`.
|
|
//
|
|
// Steps:
|
|
// 1. Split the given string on the commas present in it.
|
|
// 2. If the split operation returns less or more than 2 elements, return the
|
|
// default of `Person`.
|
|
// 3. Use the first element from the split operation as the name.
|
|
// 4. If the name is empty, return the default of `Person`.
|
|
// 5. Parse the second element from the split operation into a `u8` as the age.
|
|
// 6. If parsing the age fails, return the default of `Person`.
|
|
impl From<&str> for Person {
|
|
fn from(s: &str) -> Self {}
|
|
}
|
|
|
|
fn main() {
|
|
// Use the `from` function.
|
|
let p1 = Person::from("Mark,20");
|
|
println!("{p1:?}");
|
|
|
|
// Since `From` is implemented for Person, we are able to use `Into`.
|
|
let p2: Person = "Gerald,70".into();
|
|
println!("{p2:?}");
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use super::*;
|
|
|
|
#[test]
|
|
fn test_default() {
|
|
let dp = Person::default();
|
|
assert_eq!(dp.name, "John");
|
|
assert_eq!(dp.age, 30);
|
|
}
|
|
|
|
#[test]
|
|
fn test_bad_convert() {
|
|
let p = Person::from("");
|
|
assert_eq!(p.name, "John");
|
|
assert_eq!(p.age, 30);
|
|
}
|
|
|
|
#[test]
|
|
fn test_good_convert() {
|
|
let p = Person::from("Mark,20");
|
|
assert_eq!(p.name, "Mark");
|
|
assert_eq!(p.age, 20);
|
|
}
|
|
|
|
#[test]
|
|
fn test_bad_age() {
|
|
let p = Person::from("Mark,twenty");
|
|
assert_eq!(p.name, "John");
|
|
assert_eq!(p.age, 30);
|
|
}
|
|
|
|
#[test]
|
|
fn test_missing_comma_and_age() {
|
|
let p: Person = Person::from("Mark");
|
|
assert_eq!(p.name, "John");
|
|
assert_eq!(p.age, 30);
|
|
}
|
|
|
|
#[test]
|
|
fn test_missing_age() {
|
|
let p: Person = Person::from("Mark,");
|
|
assert_eq!(p.name, "John");
|
|
assert_eq!(p.age, 30);
|
|
}
|
|
|
|
#[test]
|
|
fn test_missing_name() {
|
|
let p: Person = Person::from(",1");
|
|
assert_eq!(p.name, "John");
|
|
assert_eq!(p.age, 30);
|
|
}
|
|
|
|
#[test]
|
|
fn test_missing_name_and_age() {
|
|
let p: Person = Person::from(",");
|
|
assert_eq!(p.name, "John");
|
|
assert_eq!(p.age, 30);
|
|
}
|
|
|
|
#[test]
|
|
fn test_missing_name_and_invalid_age() {
|
|
let p: Person = Person::from(",one");
|
|
assert_eq!(p.name, "John");
|
|
assert_eq!(p.age, 30);
|
|
}
|
|
|
|
#[test]
|
|
fn test_trailing_comma() {
|
|
let p: Person = Person::from("Mike,32,");
|
|
assert_eq!(p.name, "John");
|
|
assert_eq!(p.age, 30);
|
|
}
|
|
|
|
#[test]
|
|
fn test_trailing_comma_and_some_string() {
|
|
let p: Person = Person::from("Mike,32,dog");
|
|
assert_eq!(p.name, "John");
|
|
assert_eq!(p.age, 30);
|
|
}
|
|
}
|