Change exercise for mutable slices. Closes mainmatter#26

Author: LukeMathWalker

exercises/06_ticket_management/11_mutable_slices/src/lib.rs

@@ -1,36 +1,28 @@
-// TODO: Define a function named `lowercase` that converts all characters in a string to lowercase,
-//  modifying the input in place.
-//  Does it need to take a `&mut String`? Does a `&mut str` work? Why or why not?
+// TODO: Define a function named `squared` that raises all `i32`s within a slice to the power of 2.
+//  The slice should be modified in place.
 
 #[cfg(test)]
 mod tests {
     use super::*;
 
     #[test]
     fn empty() {
-        let mut s = String::from("");
-        lowercase(&mut s);
-        assert_eq!(s, "");
+        let mut s = vec![];
+        squared(&mut s);
+        assert_eq!(s, vec![]);
     }
 
     #[test]
-    fn one_char() {
-        let mut s = String::from("A");
-        lowercase(&mut s);
-        assert_eq!(s, "a");
+    fn one() {
+        let mut s = [2];
+        squared(&mut s);
+        assert_eq!(s, [4]);
     }
 
     #[test]
-    fn multiple_chars() {
-        let mut s = String::from("Hello, World!");
-        lowercase(&mut s);
-        assert_eq!(s, "hello, world!");
-    }
-
-    #[test]
-    fn mut_slice() {
-        let mut s = "Hello, World!".to_string();
-        lowercase(s.as_mut_str());
-        assert_eq!(s, "hello, world!");
+    fn multiple() {
+        let mut s = vec![2, 4];
+        squared(&mut s);
+        assert_eq!(s, vec![4, 16]);
     }
 }