Yes for some cases like arihant subs, nuke subs,laser weapons,mirv/marv or any technology which is not used by at least 10 countries, government should not disclose .
But for simple missiles the tests should be made public
Sure,
extended range bramhos, ship launched bramhos, air launched brahmos, new seeker bramhos, new engine bramhos, bramos with 100kg more payload, underground bramhos,etc