I have very little knowledge of ADHD and it's associated disorders and am no expert and as with anyhting the wrong diagnosis may be reached, even by experts in the field.
I do however have first hand and very close knowledge of Autism which is a very broad spectrum, and believe me you don't need a test as such - when you spend hours with a child you just know how extraordinarily special they are. You spot the signs , the triggers, whether it be a smell a particular pitch of sound whatever (different for each person, though there are some commonalities).
Plus our Golden boys are so very articulate, they will tell you what it feels like within them, I feel proud and privileged that they were born into our family.