Actually, no. "...were not any reading comprehension tests..." would be correct, the way you were trying to correct him. You would not say "There were not reading comprehension test". Were is used with plural subjects.
"...was no reading comprehension test..." was grammatically correct. Was is used with a singular subject.
Originally Posted by
Der Meister
I worked for your company (XJT) first so, no. However your sentence is grammatically incorrect. It should say "I'm guessing there were not any reading comprehension test where you worked". But I'm guessing there were not any spelling or grammer tests when you were hired either, so I can understand your deficiencies.