The fool proof test of a functioning immune system is that you don't get sick, period. You also should have good resistance to toxins and poisons if they do so happen to enter your system.
Also, I hate to say this, but the chances are VERY high that a potential partner you would find will also have candida, unless she is from some enlightened area of the world, has grown up with loving parents and natural foods, never got silver fillings or took Antibiotics etc. In this case her immune system would be good and you wouldn't have to worry anyway! Lol. If your partner does already have candida, you two can go on protocols together and support each other. It's a win win!