pub trait ByteSize {
    fn byte_size(&self) -> usize;
}

#[test]
fn reparent_window_length_is_correct() {
    // header (total: 4 bytes):
    // - major opcode (the request's "ID"): u8, 1 byte
    // - empty (for this request)
    // - length of the request: u16, 2 bytes (that's what we're calculating)
    let reparent_window = ReparentWindow {
        target: Window::new(0), // 4 bytes (`u32` wrapper)
        new_parent: Window::new(0), // 4 bytes (`u32` wrapper)
        new_x: 0, // 2 bytes (`u16`)
        new_y: 0, // 2 bytes (`u16`)
    };

    // total is 4 + 4 + 2 + 2 + (header: 4) = 16

    // length of a message is in multiples of 4 bytes, so the length should be 16 / 4 = 4
    assert_eq!(reparent_window.length(), 4);
}