102 lines
3.0 KiB
Rust
102 lines
3.0 KiB
Rust
// TryFrom is a simple and safe type conversion that may fail in a controlled way under some circumstances.
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// Basically, this is the same as From. The main difference is that this should return a Result type
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// instead of the target type itself.
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// You can read more about it at https://doc.rust-lang.org/std/convert/trait.TryFrom.html
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use std::convert::{TryInto, TryFrom};
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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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// I AM NOT DONE
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// Your task is to complete this implementation
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// in order for the line `let p = Person::try_from("Mark,20")` to compile
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// and return an Ok result of inner type Person.
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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 an error
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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 an error.
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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 an error
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// Otherwise, then return a Result of a Person object
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impl TryFrom<&str> for Person {
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type Error = String;
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fn try_from(s: &str) -> Result<Self, Self::Error> {
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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::try_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: Result<Person, _> = "Gerald,70".try_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_bad_convert() {
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// Test that error is returned when bad string is provided
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let p = Person::try_from("");
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assert!(p.is_err());
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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::try_from("Mark,20");
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assert!(p.is_ok());
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let p = p.unwrap();
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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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#[should_panic]
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fn test_panic_empty_input() {
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let p: Person = "".try_into().unwrap();
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}
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#[test]
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#[should_panic]
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fn test_panic_bad_age() {
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let p = Person::try_from("Mark,twenty").unwrap();
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}
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#[test]
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#[should_panic]
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fn test_missing_comma_and_age() {
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let _: Person = "Mark".try_into().unwrap();
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}
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#[test]
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#[should_panic]
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fn test_missing_age() {
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let _: Person = "Mark,".try_into().unwrap();
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}
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#[test]
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#[should_panic]
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fn test_missing_name() {
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let _ : Person = ",1".try_into().unwrap();
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}
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#[test]
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#[should_panic]
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fn test_missing_name_and_age() {
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let _: Person = ",".try_into().unwrap();
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}
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#[test]
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#[should_panic]
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fn test_missing_name_and_invalid_age() {
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let _: Person = ",one".try_into().unwrap();
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}
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} |