Implementation of the binary search algorithm (logarithmic search)

binary_search.rs

use std::cmp::Ordering;
pub fn binary_search(arr: &[i32], value: i32) -> Option<usize> {
    let mut mid;
    let mut low = 0;
    let high = arr.len();

    while low <= high {
        mid = low + (high - low) / 2;
        match arr.get(mid) {
            Some(arr_value) => match value.cmp(&arr_value) {
                Ordering::Less => low = mid - 1,
                Ordering::Greater => low = mid + 1,
                Ordering::Equal => return Some(mid),
            },
            None => return None,
        }
    }

    return None;
}

binary_search_test.rs

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

    #[test]
    fn it_case_0_for_binary_search() {
        let result = binary_search(&[], 10);
        assert_eq!(result, None);
    }

    #[test]
    fn it_case_1_for_binary_search() {
        let result = binary_search(&[3], 3);
        assert_eq!(result, Some(0));
    }

    #[test]
    fn it_case_2_for_binary_search() {
        let result = binary_search(&[3, 5], 5);
        assert_eq!(result, Some(1));
    }
    
    #[test]
    fn it_case_n_for_binary_search() {
        let result = binary_search(&[2, 3, 4, 5, 10, 16, 20], 16);
        assert_eq!(result, Some(5));
    }
}

info.md

Binary search runs in logarithmic time in the worst case, making O(log n) comparisons, where n is the number of elements in the array. Binary search is faster than linear search except for small arrays. However, the array must be sorted (https://gist.github.com/mikhail-krainik/cf92a17ce7a393b0779f3142a10910d5) first to be able to apply binary search.