I don't think there is any one specific ADHD test. My testing process was 3 zoom appointments. An introduction/get to know you,why are you here appointment. The second one was testing. The third was the results of testing, explanations, an overall summary with recommendations and I was given the day when a written summary would be online in my psych records that I requested to be sent to my primary doctor.
The testing sections were picked by the doctor. There were a few different tests. Some tested functional memory, some how your brain handles a complex thing, some were answering questions using a scale, some were true false. I had to draw an abstract picture after looking at it for a period of time. There were some odd questions too which the psych told me would possibly be in there. Those were there to see if you were reading and comprehending the test. They were obvious like Robert Thomas is your spouse. True or False. (I don't know anyone named Robert Thomas and I don't have a spouse.)
My suggestion is to not worry about the test. You just answer questions the best you can. There isn't a right or wrong answer. It just gives the psych some understanding of how your brain functions.
I have no experience with testing for autism.