141 lines
4.2 KiB
Rust
141 lines
4.2 KiB
Rust
// The From trait is used for value-to-value conversions.
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// If From is implemented correctly for a type, the Into trait should work conversely.
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// You can read more about it at https://doc.rust-lang.org/std/convert/trait.From.html
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// Execute `rustlings hint from_into` or use the `hint` watch subcommand for a hint.
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#[derive(Debug)]
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struct Person {
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name: String,
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age: usize,
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}
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// We implement the Default trait to use it as a fallback
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// when the provided string is not convertible into a Person object
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impl Default for Person {
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fn default() -> Person {
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Person {
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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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// Your task is to complete this implementation
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// in order for the line `let p = Person::from("Mark,20")` to compile
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// Please note that you'll need to parse the age component into a `usize`
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// with something like `"4".parse::<usize>()`. The outcome of this needs to
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// be handled appropriately.
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//
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// Steps:
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// 1. If the length of the provided string is 0, then return the default of Person
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// 2. Split the given string on the commas present in it
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// 3. Extract the first element from the split operation and use it as the name
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// 4. If the name is empty, then return the default of Person
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// 5. Extract the other element from the split operation and parse it into a `usize` as the age
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// If while parsing the age, something goes wrong, then return the default of Person
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// Otherwise, then return an instantiated Person object with the results
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impl From<&str> for Person {
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fn from(s: &str) -> Person {
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let vec: Vec<&str> = s.split(",").collect();
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let name = vec[0].trim();
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let age = vec[vec.len() - 1].parse::<usize>();
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if vec.len() == 2 && name.len() > 0 && age.is_ok() {
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Person { name: name.to_string(), age: age.unwrap() }
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} else {
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Person::default()
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}
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}
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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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// Since From is implemented for Person, we should be able to use Into
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let p2: Person = "Gerald,70".into();
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println!("{:?}", p1);
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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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// Test that the default person is 30 year old John
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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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// Test that John is returned when bad string is provided
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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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// Test that "Mark,20" works
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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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// Test that "Mark,twenty" will return the default person due to an error in parsing 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,man");
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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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