By the time Shangguan Xuanyi returned to his room, Xiao'er had already heard about their conversation from Yang Liu.
In fact, cheating in the Imperial Examinations happens every time. What matters is whether the cheater is cunning enough to avoid detection.
This sort of thing cannot be completely eradicated. If you have a clever scheme, others may have ladders to scale the walls. There is always a wall that can be climbed.
However, over the years, the majority of the examiners chosen are known for their integrity and high reputation, so the chance of manipulation has been greatly reduced in the examinations.
"Is Jinghao all right?" Xiao'er asked.
"He's fine. Someone probably tampered with his food with a drug that affects his sleep pattern. I've ordered someone to look into it." The drug wasn't poisonous, and it wouldn't be detected by a silver needle. It just made a person sleepy at improper times and very alert during times when sleep is expected.