if abc is true
    call async func1, func2
else
    call async func1

if(abc)
   Q.all([func1,func2])
else
   Q.all([func1])

function test(): Q.Promise<boolean> {
    if(abc)
       Q.all([func1,func2])
    else
       Q.all([func1])
    //if failed throw reject reason all the way in the chain
}