If you are wondering about whether food intolerance and food allergy tests are always accurate the unfortunate answer is absolutely not. Tests are designed to serve the largest segment of the human population. There are thresholds of allergens to consider. Just as there are infective doses to consider for viruses there are thresholds to consider with allergens. An infective dose of a virus is the generally accepted amount of a virus that it takes to get an average person sick. Notice that it is a general amount for an average person. For an allergy or intolerance there may be a certain amount of the allergen that is necessary that the sufferer be exposed to before symptoms manifest to the point that they are detected.
Testing for allergies on a person who is just intolerant will most often produce negative results. An uninformed sufferer who goes to a doctor for allergy testing may be told by the doctor that medical testing indicates that no such allergy exists for them. That would be because the immune system was not involved. However, just because there is no allergic response to a food does not mean that there is not an intolerance to a food.