Rust generic function

lib.rs

extern crate num;

use num::{Num, One, Zero};

pub fn number_of_factors<T>(target: T) -> T
    where T: Num + Ord + Copy
{ 
    let mut factor_count: T = Zero::zero();;
    let mut limit: T = target;
    let mut i: T = One::one();
    while i < limit {
        if target % i == Zero::zero() { 
            limit = target / i;
            if limit != i { 
                factor_count = factor_count + One::one();
            }     
            factor_count = factor_count + One::one();
        }     
        i = i + One::one();
    }
    factor_count
}

#[test]
fn test1() {
    assert_eq!(number_of_factors(9u64), 3u64);
    assert_eq!(number_of_factors(12i32), 6i32);
}