Add a panic assertion test

guessing_game/src/main.rs

@@ -2,6 +2,20 @@ use rand::Rng;
 use std::cmp::Ordering;
 use std::io;
 
+pub struct Guess {
+    value: i32,
+}
+
+impl Guess {
+    pub fn new(value: i32) -> Guess {
+        if value < 1 || value > 100 {
+            panic!("Guess value must be between 1 and 100, got {value}.");
+        }
+
+        Guess { value }
+    }
+}
+
 fn main() {
     println!("Guess the number!");
     let secret_number = rand::thread_rng().gen_range(1..=100);
@@ -16,17 +30,17 @@ fn main() {
             .read_line(&mut guess)
             .expect("Failed to read line");
     
-        let guess: u32 = match guess.trim().parse() {
-            Ok(num) => num,
+        let guess: Guess = match guess.trim().parse() {
+            Ok(num) => Guess::new(num),
             Err(_) => {
                 println!("Please type a number!");
                 continue;
             },
         };
 
-        println!("You guessed: {guess}");
+        println!("You guessed: {}", guess.value);
     
-        match guess.cmp(&secret_number) {
+        match guess.value.cmp(&secret_number) {
             Ordering::Less => println!("Too small!"),
             Ordering::Greater => println!("Too big!"),
             Ordering::Equal => {
@@ -36,3 +50,15 @@ fn main() {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    #[should_panic]
+    fn greater_than_100() {
+        Guess::new(200);
+    }
+}
+