Sum of all subset xor totals

#[test]
fn t1() {
    let start = std::time::Instant::now();
    let val = Solution::subset_xor_sum(vec![1, 3]);
    let expected = 6;
    log_result!(val == expected, "t1", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t2() {
    let start = std::time::Instant::now();
    let val = Solution::subset_xor_sum(vec![5, 1, 6]);
    let expected = 28;
    log_result!(val == expected, "t2", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t3() {
    let start = std::time::Instant::now();
    let val = Solution::subset_xor_sum(vec![3, 4, 5, 6, 7, 8]);
    let expected = 480;
    log_result!(val == expected, "t3", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t4() {
    let start = std::time::Instant::now();
    let val = Solution::subset_xor_sum(vec![7]);
    let expected = 7;
    log_result!(val == expected, "t4", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t5() {
    let start = std::time::Instant::now();
    let val = Solution::subset_xor_sum(vec![5, 5]);
    let expected = 10;
    log_result!(val == expected, "t5", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t6() {
    let start = std::time::Instant::now();
    let val = Solution::subset_xor_sum(vec![1, 2, 3]);
    let expected = 12;
    log_result!(val == expected, "t6", start, &expected, &val);
    assert_eq!(val, expected);
}