They already know what they need. For them, it can only be an amusement, or perhaps a validation. I might point out that, at Class Four, you are completely validated. Class Four means the most common kind of transsexual. It says so, right on the label.
Tests are at best indications, hints, estimations, rough guideposts and generalistic suggestions.
Even a medical blood test is just a best estimation. The body changes minute to minute. Only the individual can define themselves. However, occasionally, tests can provide direction, or provide clues, or they can assess a rough idea of what is going on. That is all any test can do.