W. Va. Code § 41-5-15
Any or all of the attesting witnesses to any will, at the request of the testator, may make and subscribe an affidavit before any officer authorized to administer oaths, in or out of the state, stating such facts as would be required of them in testimony in court to establish and prove the will; and if the testator shall preserve such affidavits with the will, and the same are produced and offered in evidence when the will is offered for probate, they shall be admissible in evidence and have the same probative value as if the affiants had appeared in court or before the clerk thereof and testified to the facts stated in the affidavit: Provided, That such affidavits shall not be admissible in evidence in any case in which there is a contest over the will.
W. Va. Code § 41-5-15