If we can compute our way to Mars we can compute our designs and yield in our labs. Not to mention we have tested our nukes not once but twice to have good amount of data at our disposal. Remember the word is
tested, unlike Pakistan who detonated something they had got from China or may be assembled in Pakistan, to sooth its national ego..
Israelis have the nuclear weapons and yet they still haven't tested.
Pakistani nuclear tests were rather embarrassment for China who jumped in, to help them but ended up watching few duds dusting mud over Chagai hills.
Only strong and reasonable argument I have seen so far against Indian nuclear weapon program is InA strategic forces having lack or may be zero practice on testing nuclear fuse, mating arsenal etc. The debate on our capabilities to make one, numbers and yield is over and done for all rational minds. Few kids across the border and 50 cent brigade will keep raising doubts on India's capabilities and we can always ignore with indifference.
I admit I haven't yet chased this argument further for what Indian side has done in this regard or even if there is any open source information available. I am tagging
@bennedose as I am aware there is plenty of material available at BR forum and most likely guys there are even done with this argument at experiment level as references are available where we have tested our missile designs to validate nuke carrying capabilities or may be nuclear fuse etc.
As far as strategic forces conducting nuclear drills and preparing for nuclear battle is concern then I don't think India enjoy favorable PR condition to have the luxury of letting such information out but keep it ambiguous.