Number of bit changes to make two integers equal

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

#[test]
fn test_example1() {
    let start = std::time::Instant::now();
    let val = Solution::min_changes(13, 4);
    let expected = 2;
    log_result!(val == expected, "test_example1", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn test_example2() {
    let start = std::time::Instant::now();
    let val = Solution::min_changes(21, 21);
    let expected = 0;
    log_result!(val == expected, "test_example2", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn test_example3() {
    let start = std::time::Instant::now();
    let val = Solution::min_changes(14, 13);
    let expected = -1;
    log_result!(val == expected, "test_example3", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn test_impossible() {
    let start = std::time::Instant::now();
    let val = Solution::min_changes(4, 3);
    let expected = -1;
    log_result!(val == expected, "test_impossible", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn test_k_zero() {
    let start = std::time::Instant::now();
    let val = Solution::min_changes(5, 0);
    let expected = 2;
    log_result!(val == expected, "test_k_zero", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn test_one_change_needed() {
    let start = std::time::Instant::now();
    let val = Solution::min_changes(7, 5);
    let expected = 1;
    log_result!(val == expected, "test_one_change_needed", start, &expected, &val);
    assert_eq!(val, expected);
}