Cover me!
South Africa is one of the few vehicle dependent countries in the world where insurance cover is not an absolute requirement to be able to drive on our roads. Your finance house will require you to have an insurance policy in place before driving away in your new car because technically the vehicle still belongs to them until it is paid off.
Related: 10 Insurance myths busted.
As a driver you can drive in South Africa without valid insurance if the car is wholly owned by you BUT this is a very bad idea! The reality is that accidents happen, and you really do want to have some sort of cover in case it all goes wrong.
We strongly advise having at least a third party, fire and theft policy in place to protect yourself.
As for the question at hand, by law no you don't need insurance to test drive car, but the seller may require it to cover themselves in the case of a private sale. Most dealerships have cover in place for test drives but if you are a first time buyer and have a relatively new license they may not be overly receptive to a test drive option so chat with your sales person first.
If you do have insurance you can check with your insurer if you have the relative cover for driving other vehicles in place and that will just make things easier for everyone concerned.