script.on_event(defines.events.on_built_entity, function(event)
	local player_index = event.player_index
	game.print("Before: " .. tostring(game.players[player_index].undo_redo_stack.get_undo_item_count()))
        event.entity.rotate{by_player=player_index}
        game.print("After: " .. tostring(game.players[player_index].undo_redo_stack.get_undo_item_count()))
end)

--Regular check.
script.on_nth_tick(120, function()
    if game.players[1] then
        game.print("Current undo stack size: " .. tostring(game.players[1].undo_redo_stack.get_undo_item_count()))
    end
end)