As with Muhammad, there is zero evidence that either tested the spirit who spoke to them.
The stories of Muhammad and Joseph Smith do have some parallels, such as claiming to have had revelations that prompted them to say that God's message to man was not complete prior to them, and introducing additional would-be "holy books" that are supposed to be the Word of God.
In the case of the LDS, they claim that the much-romanticized "early Church" (which many use as a palimpsest to make into whatever they want it to be) was, indeed, very similar to their movement today, with their temple ordinances, Aaronic and Melchizedek priesthoods, and so on. In the case of Islam, they "ret-con" the life of Jesus (Whom, to their credit, they do revere, as they do Our Lady) to suggest that portions of the Gospel did not really happen that way. We are warned in Scriptures about false teachers who will come and proclaim another gospel. (Interestingly, both Islam and the LDS urge their adherents to live clean, sober lives, eschewing alcohol, and in the case of the LDS, other consumables that they see as unwholesome. And to
their credit, as a result, LDS adherents tend to live longer, healthier lives, and their strong work ethic and sense of community and mutual assistance are not bad things, far from it.)
