lifetimes1 solution

exercises/16_lifetimes/lifetimes1.rs

@@ -3,6 +3,7 @@
 // going out of scope before it is used. Remember, references are borrows and do
 // not own their own data. What if their owner goes out of scope?
 
+// TODO: Fix the compiler error by updating the function signature.
 fn longest(x: &str, y: &str) -> &str {
     if x.len() > y.len() {
         x
@@ -12,9 +13,16 @@ fn longest(x: &str, y: &str) -> &str {
 }
 
 fn main() {
-    let string1 = String::from("abcd");
-    let string2 = "xyz";
-
-    let result = longest(string1.as_str(), string2);
-    println!("The longest string is '{}'", result);
+    // You can optionally experiment here.
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_longest() {
+        assert_eq!(longest("abcd", "123"), "abcd");
+        assert_eq!(longest("abc", "1234"), "1234");
+    }
 }

rustlings-macros/info.toml

@@ -821,9 +821,8 @@ You may need this:
 [[exercises]]
 name = "lifetimes1"
 dir = "16_lifetimes"
-test = false
 hint = """
-Let the compiler guide you. Also take a look at the book if you need help:
+Let the compiler guide you. Also take a look at The Book if you need help:
 https://doc.rust-lang.org/book/ch10-03-lifetime-syntax.html"""
 
 [[exercises]]

solutions/16_lifetimes/lifetimes1.rs

@@ -1 +1,28 @@
-// Solutions will be available before the stable release. Thank you for testing the beta version 🥰
+// The Rust compiler needs to know how to check whether supplied references are
+// valid, so that it can let the programmer know if a reference is at risk of
+// going out of scope before it is used. Remember, references are borrows and do
+// not own their own data. What if their owner goes out of scope?
+
+fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
+    //    ^^^^     ^^          ^^          ^^
+    if x.len() > y.len() {
+        x
+    } else {
+        y
+    }
+}
+
+fn main() {
+    // You can optionally experiment here.
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_longest() {
+        assert_eq!(longest("abcd", "123"), "abcd");
+        assert_eq!(longest("abc", "1234"), "1234");
+    }
+}