// Complete this function to return the factorial of a given number
use find_factorial::*;

pub fn factorial(num: u64) -> u64 {
    match num {
        0 | 1 => 1,
        _ => factorial(num - 1) * num,
    }
}

fn main() {
    println!("The factorial of 0 = {}", factorial(0)); 
    println!("The factorial of 1 = {}", factorial(1)); 
    println!("The factorial of 5 = {}", factorial(5)); 
    println!("The factorial of 10 = {}", factorial(10)); 
    println!("The factorial of 19 = {}", factorial(19)); 
}

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

    #[test]
    fn factorial_of_1() {
        assert_eq!(1, factorial(0));
        assert_eq!(1, factorial(1));
        assert_eq!(120, factorial(5));
        assert_eq!(40320, factorial(8));
        assert_eq!(3628800, factorial(10));
        assert_eq!(87178291200, factorial(14));
        assert_eq!(6402373705728000, factorial(18));
        assert_eq!(121645100408832000, factorial(19));
        assert_eq!(2432902008176640000, factorial(20));
    }
}