Is it obligatory for the suitor to inform his fiancée that he has only one testicle, given the doctors' affirmation that this does not affect his sexual capability?

A husband is not obligated to inform his wife of his physical defects unless these defects prevent or are repulsive to marital intimacy, such as insanity, leprosy, vitiligo, atresia (imperforate vagina), qarn (a fleshy growth in theana), impotence, or being castrated. The defect mentioned [in the question, which is not provided here] is neither repulsive nor does it prevent marital intimacy, so there is no obligation to disclose it.