As far as I know in the United States, no DMV provides test vehicles.
You need a vehicle to take the driving test.
Since you are not currently licensed, you can not legally drive yourself to the test alone...
So logically, you must bring someone... anyone... willing to drive you to the test and provide a vehicle for you to test in. As others have stated in the comments above, worse case scenario is the hiring of a driving instructor.
If you read the written instructions (and I remember correctly), it does state something along the lines of "must be accompanied by a licensed driver and provide an insured, registered, vehicle". Which is a bit more formal than the "bring a friend". Most people just naturally use more casual terms when speaking. I don't know your age, but it's probably more common to hear "bring a parent" than "bring a friend" when speaking face to face with the DMV staff.
Also, not all insurance policies are driver limited. Some policies are on the vehicle regardless of driver. Typically Liability-only insurance is vehicle specific, not driver specific. [*1] You'd have to review the policies or call the insurance agents to confirm this.
You may even do something as simple as add you to the current insurance for a month or two while you're practicing and testing. Just reimburse your friend for any increase in premiums during this time. Contact the insurance company/agent. The cost may be minimal.
In addition, there are non-owner insurance policies which cover you even if you do not own a vehicle. This would provide insurance if none of your friends has a policy which would work.
Realize that most people taking the test for the first time have probably already been added to a policy owned by their parents. So, your situation is a bit more unique. It's not meant to be inherently confusing but if you're "outside the norm" you have to do some deductive reasoning on your own.
And finally, if an accident or damage were to happen during your practicing or testing, it would still be your responsibility. If you are in control of the vehicle, you are responsible for any damage to it or damage caused by the vehicle due to any negligence on your part, regardless of any insurance policy. You'd be a pretty bad "friend" if you caused damage and didn't financially make restitution leaving your "friend" holding the bag, so to speak. Restitution could be something as simple as paying the deductible on your friend's policy. Of course, if you are not covered by insurance any claim may be denied -- leaving you responsible for everything. The mindset that just because your friend owns the car they are totally responsible for anything that happens while your driving seem very, very self-serving and, well, I'd be apprehensive about loaning you my vehicle as well. In fact, I absolutely would not.