Easiest and cheapest way I've found is to buy one of those el cheapo 'ultrasonic' jewelry cleaners and get ahold of a portable drill stand and a water separator for an air compressor line and some fittings and a length of 1/2" heater hose.
Mount the water separator to the stand and connect the hose to it with the proper fittings and leave the other end of the hose raw with just a clamp on the end.
You can use your compressor @about 40-60 psi or you can even use a bicycle pump (just put a schrader valve on the water separator inlet).
To test for leaking injectors, clamp an injector into the raw end of the hose and fill the water separator with fuel injector cleaner and pressurize it with the pump/compressor.
If the injector leaks, you'll know right away.
Take a piece of coat hanger and bend it so it can hang from the drill stand and so there's a small loop on one end on a right angle-depressurize the injector and unclamp it from the hose and put it in the loop with the nozzle end facing downward.
Take your 'ultrasonic', battery powered $3 jewelry cleaner and fill it with injector cleaner and lower the injector into it (submerge the nozzle ned only-not the whole injector). Turn on the cleaner and relax...TONS of crap will fall out of that injector).
Flip it over after awhile to clean the inlet screen end and be amazed at the crud that falls out.
I made a momentary firing switch (SPST switch mounted in a plastic box with bog alligator clips such as those found on an old battery charger on the battery end and a salvaged injector plug on the other, the switch is wired inline on the positive side).
This way I can clamp that injector back into the hose end and pressurize it again and tap that switch to observe the spray pattern.
Now I dunno what the official spray pattern is supposed to look like but I do know it's supposed to be a fine mist in a more or less conical pattern.
This appears to be good enough.
My engines aren't complaining
