Another script that I used to test if my impersonation works is as below:

var og = gs.getSession().impersonate('5136503cc611227c0183e96598c4f706'); 

gs.print(gs.getUser().getFullName()); 


var gr1 = new GlideRecord('sn_customerservice_case'); 

gr1.addQuery('sys_id',b08cd51fdba83a007a4cbedffe96196d'); 

gr1.query(); 

if(gr1.next()) 

gs.print("Found it"); 

else 

gs.print("Not Found"); 


gs.getSession().impersonate(og); 

*** Script: Guest

*** Script: Not Found