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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> {
match hour_of_day {
0..=21 => Some(5),
22..=23 => 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);
}
}
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