at·test /ə-'test/ vb [Latin attestari, from ad to + testari to call to witness, from testis witness]
vt: to bear witness to: affirm to be true or genuine; specif: to authenticate (as a will) by signing as a witness
vi: to bear witness: testify
— often used with to
at·tes·ta·tion /ˌa-ˌtes-'tā-shən/ n
Merriam-Webster’s Dictionary of Law. Merriam-Webster. 1996.