Quick definitions from WordNet (attest)
▸ verb: authenticate, affirm to be true, genuine, or correct, as in an official capacity ("I attest this signature")
▸ verb: establish or verify the usage of ("This word is not attested until 1993")
▸ verb: provide evidence for; stand as proof of; show by one's behavior, attitude, or external attributes ("His high fever attested to his illness")
▸ verb: give testimony in a court of law
▸ Also see attest
▸ verb: authenticate, affirm to be true, genuine, or correct, as in an official capacity ("I attest this signature")
▸ verb: establish or verify the usage of ("This word is not attested until 1993")
▸ verb: provide evidence for; stand as proof of; show by one's behavior, attitude, or external attributes ("His high fever attested to his illness")
▸ verb: give testimony in a court of law
▸ Also see attest