What is the test for impeaching a witness in a criminal case?

California courts have, in cases similar to this one, held the court's exclusion of collateral facts offered for impeachment purposes to be a proper exercise of the trial judge's discretion. In People v. Atchley [ (1959) ] 53 Cal.2d 160, 346 P.2d 764[, cert. dism. (1961) 366 U.S. 207, 81 S.Ct. 1051, 6 L.Ed.2d 233], defendant was on trial for the murder of his wife. Defendant attempted to impeach a prosecution witness by showing that she had forged rent receipts for the deceased to deceive the welfare department after she testified on cross-examination that she never forged a rent receipt. That case, like this one, involved an attempted impeachment of a prosecution witness on a collateral matter involving a crime with which the witness was neither charged nor convicted. In that case we held that the trial court had discretion to foreclose further inquiry into the forgery issue, even for purposes of impeachment.... That case would seem to govern here.