Ah. I see where you're coming from. Don't know. MOTs in NI are done by the DVA ( Driver and Vehicle Agency ) in central locations. The test is thorough and consistent.
Had this problem on my W203.....cleaned the nozzles with a pin...seemed to make a small difference as got a dribble of water out....then realised that there was a flood of water coming out of the bottom of the tailgate....took tailgate panel off and found that the pipe joint to the rear of the motor was loose....pushed it back together and, hey-presto, washer jet working as it should!!