I've been going to 7 Days a Week Smog for years. On my most recent smog check, I hadn't noticed that the engine light was on. They told they'd wait on the Groupon and to just bring it back when the problem was gone and the error codes reset and ready. Very civilized.
I will say that they used to have better snacks in the waiting room—but it's amazing that they even have a waiting room, let alone snacks.
I go to this place every two years to smog both of my vehicles. It only cost $38.00 and some chump change. This year I got an extra $3.50 off because of a special promotional coupon. Its a hidden gem, so you either have to arrive early in the morning when they first open or make an appointment. I arrived 30 minutes before they opened. My car was done 20 minutes later. They have a small seating area with a tv. The staff is extremely friendly.
This was a really good deal and the SMOG testing service was great. No hassle, no fuss. I will absolutely buy this again for my next vehicle that needs it.