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