Mo. Rev. Stat. § 115.233
Within fourteen days prior to an election at which an electronic voting system is to be used, the election authority shall have the automatic tabulating equipment tested to ascertain that the equipment is in compliance with the law and that it will correctly count the votes cast for all offices and on all questions. At least forty-eight hours prior to the test, notice of the time and place of the test shall be mailed to each independent and new party candidate and the chairman of the county committee of each established political party named on the ballot. The test shall be observed by at least two persons designated by the election authority, one from each major political party, and shall be open to representatives of the political parties, candidates, the news media and the public. The test shall be conducted by processing a preaudited group of ballots. If any error is detected, the cause shall be ascertained and corrected, and an errorless count shall be made before the tabulating equipment is approved.
§ 115.233, RSMo