No. Neither test is 100% accurate, but I would avoid any positives on either test.
Ok, I guess it depends on the circumstances. How old is the child? If old enough to talk and describe to you any symptoms- my tongue feels funny, my stomache hurts, etc. then maybe. How old was the child when the test was done? They are less reliable under 2yo. What's the food? If peanuts, NO WAY. If carrots, possibly- if I felt like it was something that was really important to have in my diet. How long have you been avoiding the food? Have you worked on gut healing before trying to reintroduce?
There are a lot of factors... not just a simple yes or no question.