Did they forget to test it?
The MOT tester left the wifi/bluetooth thingy that links car to computer emission analyzer plugged into the OBD2 port of the car so yes it got tested
back story of the car..... it's not an ebay banger, my mum has had it since nearly new (about 2000 miles on the clock) purchased from a Vauxhall main stealer, I've checked it over and serviced it etc every year including rust proofing etc ,it's now on 60,000 miles, never failed an MOT
Bangernomics wise ,it's a real fail due to the initial purchase price
(18 years, £10,000 is £550 a year loss ,not including service items )