In Texas, a will is self-proved if it complies with 59 of the Texas Probate Code, which provides as follows: Every last will and testament, except where otherwise provided by law, shall be in writing and signed by the testator in person or by another person for him by his direction and in his presence, and shall, if not wholly in the handwriting of the testator, be attested by two or more credible witnesses above the age of fourteen years who shall subscribe their names thereto in their own handwriting in the presence of the testator. Such a will or testament may, at the time of its execution or at any subsequent date during the lifetime of the testator and the witnesses, be made self-proved, and the testimony of the witnesses in the probate thereof may be made unnecessary, by the affidavits of the testator and the attesting witnesses, made before an officer authorized to administer oaths under the laws of this State. Provided that nothing shall require an affidavit or certificate of any testator or testatrix as a prerequisite to self-proof of a will or testament other than the certificate set out below. TEX. PROBATE CODE ANN. 59(a) (Vernon 1980).