This is a realistic answer and I'm assuming the question is about an actual, real life exam. There are several types of exams:
Void test: This is mostly for older guys, I believe. You are sent to the bathroom, fully dressed, and told to pee. You pee into the toilet as usual, except they may give you a little jar and ask you for a mid-pee urine sample. When done, you return to the exam room and sit on the couch. They then ask you to undo your belt and unzip your pants and put some ultrasound jelly on your tummy and then 'scan' your bladder with something like a BVI-300 Bladder Scanner to determine the residual volume of pee in your bladder. It's completely painless. Very occasionally, they may catheterize you and drain the residual to measure it.
https://monetmedical.com/product/verathon-bvi-3000-bladder-scanner/
The next step up is a Uroflow test. You may be fully dressed or be asked to put on a gown. During this test, you sit on a special commode and pee into a special funnel. Below the funnel is a sensor which measures how much you pee per second and the attached control unit displays your pee rate vs time plus some other measurements. Here is a typical setup:
http://www.clinicabritannia.com/what-is-uroflowmetry/
After you've had these tests, you doctor may order a Urodynamics test. This is far more complex. You must get completely undressed, except for socks and a gown. You then climb into a Urodynamics chair, like this:
https://continencematters.com/surgery-and-procedures/having-urodynamics/
When you are settled, with your feet in the stirrups, legs spread wide, preparation for the test begins. These include:
Having you pee into a funnel positioned between your legs, as in a Uroflow test, to void your bladder and measure the pee volume.
Sometimes you get cathed, in and out, to be sure your bladder is empty.
Several sticky electrodes, like for an EKG, are attached to your groin area near your anus.
A small diameter (8 Fr) rectal pressure probe is inserted and taped to you
Another probe, also Fr 8 is inserted into your urethra and up into your bladder
And now the fun starts. An x-ray is taken of your bladder area. (the x-ray machine is the big "C" shaped thing in the pic above)
You are asked to cough several times to calibrate the system and then the fill starts. The Urdynamics machine pumps sterile saline, sometimes with an x-ray opaque dye, into your bladder at abut 1 ml/second. You are asked to tell the nurse when you feel full, first feel an urge to pee, can't hold it, and so on. The fill takes at least 5 minutes, but can take a lot longer. X-rays of your filling bladder are also taken. The filling continues until you leak.
At this point the voiding starts. You are asked to pee into the funnel below you and the flow rate and bladder pressures are measured. The rectal pressure is subtracted from the bladder pressure. When you are done peeing, the catheters are removed. If the volume voided is less than the volume injected you are again cathed to completely empty you of solution.
And you're done. I expected it to be kinda a sensuous trip, but in reality was disappointed. All very clinical and trying to hold the bladder fill was not easy.
And so it goes.