I think being able to attack your own village to test out a new design or ideas could be a neat feature to be added. It would make designing bases a lot more fun and give some sort of pass time.
It could work by taking to a different window and allow you to create an army for free in which you would be attacking your own base with just to test it out on different kind of assaults. It shouldn't cost any resources or requiring to rearm traps at the end.
Sorry if this idea is a repeat. Just came to mind.
this has been ruled out for a while now and for many reasons
but now with clan wars out you could make a base identical to someone you want to attack and practice 3-4 times until you are sure you will win