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40 lines
1.0 KiB
Rust
40 lines
1.0 KiB
Rust
// This function returns how much icecream there is left in the fridge.
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// If it's before 22:00 (24-hour system), then 5 scoops are left. At 22:00,
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// someone eats it all, so no icecream is left (value 0). Return `None` if
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// `hour_of_day` is higher than 23.
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fn maybe_icecream(hour_of_day: u16) -> Option<u16> {
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match hour_of_day {
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0..=21 => Some(5),
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22..=23 => Some(0),
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_ => None,
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}
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}
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fn main() {
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// You can optionally experiment here.
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn raw_value() {
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// Using `unwrap` is fine in a test.
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let icecreams = maybe_icecream(12).unwrap();
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assert_eq!(icecreams, 5);
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}
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#[test]
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fn check_icecream() {
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assert_eq!(maybe_icecream(0), Some(5));
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assert_eq!(maybe_icecream(9), Some(5));
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assert_eq!(maybe_icecream(18), Some(5));
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assert_eq!(maybe_icecream(22), Some(0));
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assert_eq!(maybe_icecream(23), Some(0));
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assert_eq!(maybe_icecream(24), None);
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assert_eq!(maybe_icecream(25), None);
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}
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}
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