Motivation
----------
I'm currently doing the rustlings course. I was pretty lost at quiz3 because I did not understand the problem.
With this change I would have understood that it should be possible to use both `f32` or `&str` for the grade.
I also googled quiz3 and found that other people got confused and used enums: https://www.reddit.com/r/learnrust/comments/wccx7s/rustlings_blocked_on_quiz3/
<details>
<summary>My solution, hopefully I got it now</summary>
```
// quiz3.rs
//
// This quiz tests:
// - Generics
// - Traits
//
// An imaginary magical school has a new report card generation system written
// in Rust! Currently the system only supports creating report cards where the
// student's grade is represented numerically (e.g. 1.0 -> 5.5). However, the
// school also issues alphabetical grades (A+ -> F-) and needs to be able to
// print both types of report card!
//
// Make the necessary code changes in the struct ReportCard and the impl block
// to support alphabetical report cards. Change the Grade in the second test to
// "A+" to show that your changes allow alphabetical grades.
//
// Execute `rustlings hint quiz3` or use the `hint` watch subcommand for a hint.
// I AM NOT DONE
use std::fmt::Display;
pub struct ReportCard<T: Display> {
pub grade: T,
pub student_name: String,
pub student_age: u8,
}
impl <T: Display> ReportCard<T> {
pub fn print(&self) -> String {
format!("{} ({}) - achieved a grade of {}",
&self.student_name, &self.student_age, &self.grade)
}
}
mod tests {
use super::*;
#[test]
fn generate_numeric_report_card() {
let report_card = ReportCard {
grade: 2.1,
student_name: "Tom Wriggle".to_string(),
student_age: 12,
};
assert_eq!(
report_card.print(),
"Tom Wriggle (12) - achieved a grade of 2.1"
);
}
#[test]
fn generate_alphabetic_report_card() {
// TODO: Make sure to change the grade here after you finish the exercise.
let report_card = ReportCard {
grade: "A+",
student_name: "Gary Plotter".to_string(),
student_age: 11,
};
assert_eq!(
report_card.print(),
"Gary Plotter (11) - achieved a grade of A+"
);
}
}
```
</details>
Otherwise it won't actually test the change of state.message and
it would fail to check if the user missed changing state.message
This happened to me as I had a catch-all line in `match`
The existing test functions only check if a kind of fruit exists in the hashmap, but not if the amount of fruits is higher than zero. This new test function solves this.
