Whenever a position in the classified service becomes vacant the appointing authority, if it desires to fill the vacancy, shall make requisition upon the civil service director whereupon the civil service director shall certify the names of the three persons highest on the reemployment list, or where there is no reemployment list the director shall certify the names of the three highest on the promotional list. In case there are less than three names on the reemployment or promotional lists, the director shall certify the number of names remaining on said lists willing to accept appointment provided that no name shall be certified from an employment list as long as there is a reemployment list or a promotional list for the class. The appointing authority shall at its discretion appoint one of the persons so certified for the working test period. At the end of the working test period the appointing officer shall notify the civil service director in writing whether the probationer is a satisfactory employee and should receive the status of a permanent appointee. Upon such notice the employee, if service during the working test period did not fall below such minimum standards as have been prescribed by the civil service director, shall be deemed to have a permanent classified civil service status; otherwise the employee is automatically separated from the service.