Initial commit

exercises/12_options/options1.rs

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+// 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> {
+    // TODO: Complete the function body.
+    let result: Option<u16>;
+    if hour_of_day < 22 {
+        result = Some(5);
+    } else if (22..=23).contains(&hour_of_day) {
+        result = Some(0)
+    } else {
+        result = None
+    }
+    result
+}
+
+fn main() {
+    // You can optionally experiment here.
+}
+
+#[cfg(test)]
+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).unwrap();
+
+        assert_eq!(icecreams, 5); // Don't change this line.
+    }
+
+    #[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);
+    }
+}