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+// 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);
+ }
+}