rustlings/exercises/options/options1.rs

// options1.rs
// Execute `rustlings hint options1` or use the `hint` watch subcommand for a hint.

// I AM NOTDONE

// This function returns how much icecream there is left in the fridge.
// If it's before 10PM, there's 5 pieces left. At 10PM, someone eats them
// all, so there'll be no more left :(
// TODO: Return an Option!
fn maybe_icecream(time_of_day: u16) -> Option<u16> {
    // We use the 24-hour system here, so 10PM is a value of 22
    // The Option output should gracefully handle cases where time_of_day > 24.
    match time_of_day {
        val if time_of_day < 22 => Some(5),
        val if time_of_day < 25 => Some(0),
        _ => None,
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn check_icecream() {
        assert_eq!(maybe_icecream(9), Some(5));
        assert_eq!(maybe_icecream(10), Some(5));
        assert_eq!(maybe_icecream(23), Some(0));
        assert_eq!(maybe_icecream(22), Some(0));
        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);
        println!("ans is {}",icecreams.unwrap());
        assert_eq!(icecreams.unwrap(), 5);
    }
}