Hack             Review              Test                           
 
        =========         ==========         ==========                        
 
                                                                               
 
                   push              approve                                   
 
              +-------------+    +-------------+                               
 
              |             |    |             |                               
 
       +------+--+       +--v----+--+       +--v-------+                       
 
       |         |       |          |       |          |                       
 
       | $EDITOR |       |  Gerrit  |       |   Zuul   |                       
 
       |         |       |          |       |          |                       
 
       +------^--+       +--+----^--+       +--+-------+                       
 
              |             |    |             |                               
 
              +-------------+    +-------------+                               
 
                   clone              merge