Recently I've added quiescence search to my engine. Then I realized that I need a specialized move generator that only generates captures/promotions (generating every move and filtering out 'quiet' moves is a big performance hit).
I've implemented the move generator but of course it has some bugs. The easiest way to fing bugs in move generator was to do compare perft divide with other engine. And then run perft divide which gives perft for each branch from root position (as explained here: http://www.rocechess.ch/perft.html). However I don't know of any engine that does perft-divide for captures/promotions/tactical moves only.
I'm comparing my engine with results from here: https://www.chessprogramming.org/Perft_Results
Actually I know already that the bug is somewhere in promotion generation but I guess it makes sense to make life easier
Update 24.01.2021. Actually I realized that expected data is wrong. I just summed captures and promotions from the table which makes me count my capturing promotions twice.