What is the test for a motion to exclude a witness from the witness list?

cannot hear the testimony of other witnesses, but also provides that [a] party to the action cannot be excluded under this section. The purpose of [a witness exclusion] order is to prevent tailored testimony and aid in the detection of less than candid testimony. (People v. Valdez (1986) 177 Cal.App.3d 680, 687, 223 Cal.Rptr. 149.) We review a ruling on a motion to exclude witnesses for abuse of discretion. (People v. Griffin (2004) 33 Cal.4th 536, 574, 15 Cal.Rptr.3d 743, 93 P.3d 344.)