most test kits properly instruct you on this, but you can dissolve your entire dose, or the entire batch, in water, test that, then either consume like that or

most test kits properly instruct you on this, but you can dissolve your entire dose, or the entire batch, in water, test that, then either consume like that or let the water evaporate in other words, testing a portion doesn't consume that portion, so you can literally test and then consume the same dose stay safe