I was officially diagnosed with ADHD three years ago.
There is no one test to get diagnosed and you can't self diagnose. Even your therapist can't if they don't have the training and experience to do so.
ADHD diagnosis involves interviews with people that knew you when you were a child, any mental health professionals youve worked with and a series of tests measuring intelligence, executive function, self questionaires and how you interact with the tests and the people testing you. i.e that indecisiveness would be taken into account in a professional screening. You aren't really being tested for ADHD or autism so much as trying to rule out alternative explanations.
And its also why you shouln't diagnose yourself with either of them despite what a lot of people think. Because sure it could be ADHD or autism but it could be a lot of other things that dont respond well to the same things that autism and ADHD do and you need people that actually know how to rule those things out or if it happens that you arent in the ADHD/autism tribes, figure out what tribe you actually belong to.