[SPAM] question about nounify and integrate

Hello everyone,

I've still problems to understand the behavior of noun forms, today it's 
with nounify(integrate). I was expecting that 'integrate(f(x),x,a,b) 
doesn't compute the integral, this is the case except if  f(x)=1 :


(%i1) 'integrate(1,x,0,2);
(%o1)                                  2
(%i2) 'integrate(f(x),x,0,2);
                                    2
                                   /
                                   [
(%o2)                             I  f(x) dx
                                   ]
                                   /
                                    0
(%i3) 'integrate(cos(x),x,0,2);
                                   2
                                  /
                                  [
(%o3)                            I  cos(x) dx
                                  ]
                                  /
                                   0

Perhaps there is a good reason for this I don't understand, on the other 
hand is there a way to  obtain the more general behavior below for any 
expression f(y) not depending on x :

(%i1) 'integrate(f(y),x,0,2);
                                    2
                                   /
                                   [
(%o1)                             I  f(y) dx
                                   ]
                                   /
                                    0
Best regards,
Philippe