Maximum product of two elements in an array

#[test]
fn t1() {
    let start = std::time::Instant::now();
    let val = Solution::max_product(vec![3, 4, 5, 2]);
    let expected = 12;
    log_result!(val == expected, "t1", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t2() {
    let start = std::time::Instant::now();
    let val = Solution::max_product(vec![1, 5, 4, 5]);
    let expected = 16;
    log_result!(val == expected, "t2", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t3() {
    let start = std::time::Instant::now();
    let val = Solution::max_product(vec![3, 7]);
    let expected = 12;
    log_result!(val == expected, "t3", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t4() {
    let start = std::time::Instant::now();
    let val = Solution::max_product(vec![10, 2, 5, 2]);
    let expected = 36;
    log_result!(val == expected, "t4", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t5() {
    let start = std::time::Instant::now();
    let val = Solution::max_product(vec![1, 1]);
    let expected = 0;
    log_result!(val == expected, "t5", start, &expected, &val);
    assert_eq!(val, expected);
}