feat: progress iterators

exercises/18_iterators/iterators1.rs

@@ -13,13 +13,13 @@ mod tests {
         let my_fav_fruits = &["banana", "custard apple", "avocado", "peach", "raspberry"];
 
         // TODO: Create an iterator over the slice.
-        let mut fav_fruits_iterator = todo!();
+        let mut fav_fruits_iterator = my_fav_fruits.iter();
 
         assert_eq!(fav_fruits_iterator.next(), Some(&"banana"));
-        assert_eq!(fav_fruits_iterator.next(), todo!()); // TODO: Replace `todo!()`
+        assert_eq!(fav_fruits_iterator.next(), Some(&"custard apple")); // TODO: Replace `todo!()`
         assert_eq!(fav_fruits_iterator.next(), Some(&"avocado"));
-        assert_eq!(fav_fruits_iterator.next(), todo!()); // TODO: Replace `todo!()`
+        assert_eq!(fav_fruits_iterator.next(), Some(&"peach")); // TODO: Replace `todo!()`
         assert_eq!(fav_fruits_iterator.next(), Some(&"raspberry"));
-        assert_eq!(fav_fruits_iterator.next(), todo!()); // TODO: Replace `todo!()`
+        assert_eq!(fav_fruits_iterator.next(), None); // TODO: Replace `todo!()`
     }
 }

exercises/18_iterators/iterators2.rs

@@ -7,7 +7,7 @@ fn capitalize_first(input: &str) -> String {
     let mut chars = input.chars();
     match chars.next() {
         None => String::new(),
-        Some(first) => todo!(),
+        Some(first) => char::to_uppercase(first).to_string(),
     }
 }