options1 solution

exercises/12_options/options1.rs

@@ -1,12 +1,9 @@
 // This function returns how much icecream there is left in the fridge.
-// If it's before 10PM, there's 5 scoops left. At 10PM, someone eats it
-// all, so there'll be no more left :(
-fn maybe_icecream(time_of_day: u16) -> Option<u16> {
-    // We use the 24-hour system here, so 10PM is a value of 22 and 12AM is a
-    // value of 0. The Option output should gracefully handle cases where
-    // time_of_day > 23.
-    // TODO: Complete the function body - remember to return an Option!
-    ???
+// If it's before 22:00 (24-hour system), then 5 scoops are left. At 22:00,
+// someone eats it all, so no icecream is left (value 0). Return `None` if
+// `hour_of_day` is higher than 23.
+fn maybe_icecream(hour_of_day: u16) -> Option<u16> {
+    // TODO: Complete the function body.
 }
 
 fn main() {
@@ -17,6 +14,14 @@ fn main() {
 mod tests {
     use super::*;
 
+    #[test]
+    fn raw_value() {
+        // TODO: Fix this test. How do you get the value contained in the
+        // Option?
+        let icecreams = maybe_icecream(12);
+        assert_eq!(icecreams, 5);
+    }
+
     #[test]
     fn check_icecream() {
         assert_eq!(maybe_icecream(0), Some(5));
@@ -24,14 +29,7 @@ mod tests {
         assert_eq!(maybe_icecream(18), Some(5));
         assert_eq!(maybe_icecream(22), Some(0));
         assert_eq!(maybe_icecream(23), Some(0));
+        assert_eq!(maybe_icecream(24), None);
         assert_eq!(maybe_icecream(25), None);
     }
-
-    #[test]
-    fn raw_value() {
-        // TODO: Fix this test. How do you get at the value contained in the
-        // Option?
-        let icecreams = maybe_icecream(12);
-        assert_eq!(icecreams, 5);
-    }
 }

rustlings-macros/info.toml

@@ -603,7 +603,7 @@ hint = """
 Options can have a `Some` value, with an inner value, or a `None` value,
 without an inner value.
 
-There's multiple ways to get at the inner value, you can use `unwrap`, or
+There are multiple ways to get at the inner value, you can use `unwrap`, or
 pattern match. Unwrapping is the easiest, but how do you do it safely so that
 it doesn't panic in your face later?"""
 

solutions/12_options/options1.rs

@@ -1 +1,38 @@
-// Solutions will be available before the stable release. Thank you for testing the beta version 🥰
+// This function returns how much icecream there is left in the fridge.
+// If it's before 22:00 (24-hour system), then 5 scoops are left. At 22:00,
+// someone eats it all, so no icecream is left (value 0). Return `None` if
+// `hour_of_day` is higher than 23.
+fn maybe_icecream(hour_of_day: u16) -> Option<u16> {
+    match hour_of_day {
+        0..22 => Some(5),
+        22..24 => Some(0),
+        _ => None,
+    }
+}
+
+fn main() {
+    // You can optionally experiment here.
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn raw_value() {
+        // Using `unwrap` is fine in a test.
+        let icecreams = maybe_icecream(12).unwrap();
+        assert_eq!(icecreams, 5);
+    }
+
+    #[test]
+    fn check_icecream() {
+        assert_eq!(maybe_icecream(0), Some(5));
+        assert_eq!(maybe_icecream(9), Some(5));
+        assert_eq!(maybe_icecream(18), Some(5));
+        assert_eq!(maybe_icecream(22), Some(0));
+        assert_eq!(maybe_icecream(23), Some(0));
+        assert_eq!(maybe_icecream(24), None);
+        assert_eq!(maybe_icecream(25), None);
+    }
+}