Flex testing is a very important thing to do if you want to lower the chances of having a shooting accident! It doesn't take long, and it's a good habit to pick up.
Step 1: Flex Testing
To flex test simply hold either end with your hands and start by bending it slightly while checking for any embrasures, and listening for any splintering sounds. Another good thing to do (Still holding both ends of your arrow) is to twist your hands in opposite directions while looking and listening for again, embrasures and splintering sounds.
Step 2: Your Nocks and Arrow Tips
Look at your nock see if it's loose, if it is then where the nock rests may have a crack in it. Also, don't shoot your arrow if the nock itself has a crack in it. Do the same with the tip. You'll get embrasures and cracks in your arrows by treating them too roughly, and by hitting too many hard targets (e.g wood), another way is if while shooting, one of your arrows hits another one previously shot before. If you do happen to shoot a damaged arrow, the force of the bowstring may cause the arrow to splinter and send several shards clear through your hand. I hoped this helped and hopefully you'll never have an accident!