Verify password of current user, even when it’s root

Is there a simple command to verify the password of the current user? The command $ su -c true $(id -nu) suffices for non-root users. However a root user doesn’t need to verify his identity when using su. Is there an alternative command with which a root user can safely and simply verify that the root password he remembers is still correct? I use a desktop linux distribution, Arch Linux to be particular.