Lcchang“Did speaker B pass the test?”
We don't know.
Lcchang“ how about saying "I wish I did" ?”
This sin't the standard phrase for this situation. You could use it here:
I don't know him personally. I wish I did!
Lcchang“How about "I wish I didn't" ? Do they sound the same?”
Again, I wish I didn'tn is the wrong phrase for this situation.
CB