A testament is a document that the author has sworn to be true.Testament can refer to: Old Testament, also known as the Tanakh, the holy scriptures of Judaism and Christianity. New Testament, holy scriptures of Christianity including the Gospels, epistles of Paul, and other writings. Qur'an, also known as the Final Testament, the holy scriptures of Islam. Will , a document detailing wishes upon the author's death and one of the original uses of testament; often