Honestly, he's too young to test for this. Typically, a child is diagnosed when he or she is in early elementary school. This is because some of these behaviors are age-appropriate and will go away as he matures. Yes there are doctors who will test at this age and hand out medication like it's candy, but you don't really want that kind of doctor.
That said, your son's symptoms don't scream AD/HD to me. AD/HD can sometime be *just* hyperactivity, but that's pretty rare. There is usually a cognitive component as well, where he can't attend to directions, has trouble with organization and memory, etc. and these will show up in school. These are not really skills that one would expect in a four-year-old but they are critical part of an accurate diagnosis, which is why it's a diagnosis for an older child.
So...what can you do now? I would push aside the thoughts of AD/HD because that will limit the lens through which you examine his behavior. Assume he doesn't have it (for now - revisit the idea if he has trouble in elementary school). The rage and energy are part of his temperament, they are not things that you need to fix. What you do need to fix is his behavior and how he channels that rage and energy. I would strongly, strongly recommend the books "Raising Your Spirited Child" and "The Kadzin Method for Parenting Your Defiant Child."
I would also examine his diet - is he getting enough whole grains, good fats and protein? Are you limiting preservatives, dyes, and refined sugars? I would strongly recommend giving him a high-quality fish oil supplement - Nordic Naturals ProDHA is a strawberry-flavored gel cap that is really yummy.
FWIW, my oldest son sounded a lot like your child, but his misbehavior was (thankfully) reserved for mostly at home. At daycare, he would just refuse to participate in anything. He had a sense of rage that was so disproportional to someone so young, needed very little sleep and would just defy, defy, defy me. We consulted with a psychologist to get some specific tips on how to work with him so that we didn't get locked into knock down, drag out, hours long stand-offs over simple expectations. Thankfully, he outgrew a lot of these behaviors by around age 5, but the intense feelings are still there, still very much a part of his personality at age 13. He was dx'd with AD/HD in 2nd grade but it was the result of learning disability testing and not behavior. He was put on an accommodation plan and later and IEP for LDs. We have also worked with an alternative nutritionist who helped us craft a supplement regimen that really helped during some rough years. Fish oil was a start, but we also gave him things to help with his adrenals, a chemical de-tox, and a whole bunch of other things. We recently tried a process called BIT (Brain Integration Technique or crossinology) and the results are promising. Organized sports have been a huge help as exercise and mood are strongly linked. My son probably has seasonal depression (his nasty moods used to escalate in late winter) but since he's been playing hockey for the past two years, we haven't had the late-winter blues. It's been a long road but I can say that overall, he's a good kid and has lots of friends, has the usual behavior problems from a boy his age, and is doing quite well in school with a lot of support. He is very charming and his teachers love him. Definitely not the brightest bulb on the tree, but he gets by and will do just fine. Ten years ago I was wondering if I had a juvenile delinquent in the making on my hands, and with a lot of work, and trial and error, we settled into a spot where he is comfortable in his own skin and in his own head.
Google "spirited child" and I bet you'll find a lot of kids who seem like yours, and a lot of ideas and resources to help him manage himself. Keep in mind that he's just a little boy and doesn't choose to be this way. He doesn't know what drives him and doesn't do this on purpose.
ETA @MR I appreciate your expertise on this but really, my son saw three doctors in the span of 2 months and each one of them had me fill out the same questionnaire (the one with all of the AD/HD symptoms) and each one of them handed me a prescription for stimulant medication and sent us on our way with advice to follow up in 30 days to see if it was working. The appointments were all 10-15 minutes, tops. When I expressed - repeatedly - that I wanted to rule out other problems and was interested in other therapies either in place of or in addition to medication, I was met with basically shoulder shrugging and blank stares. I wasn't even doctor shopping - the first was my pediatrician, and when I said I wanted to work with a specialist he did the same thing and then I sought out an expert in distinguishing between LDs and ADHD (at Mass General Hospital in Boston, so a guy with some serious credentials) and he did it too.
So yes, C. does need to get an evaluation for her son and consider all causes and treatments. But the over-use of stimulant medication as the first - and often only offered - means of treating what is still a complex set of symptoms with an unknown cause is very real. There is research behind supplements, particularly fatty acids. The study with which I am most familiar is Oxford-Durham and I don't think that the study has been discredited. Let's not jump to the conclusion that every solution outside of stimulant medication for AD/HD is a waste of time and money. It's not. The brain can be strengthened, healed, calmed, and made more efficient by many means.