My friends baby was tested at birth. They test the babies meconium if you tested positive at any point in your pregnancy. If you test positive a case will be open with CPS!!
....also I did breastfeed and still do (19 months!!!!) and I started smoking pot occaisionally when my son was about 6 months old and not really nursing much anymore and more eating people food.... I did do research on b-feeding and Pot and there is not much - but I did find a study that found when a newborn's (baby under 1 month old) mother smoked pot - the baby had delays at one year.... just something to keep in mind...
They will definatly ask you about drug use - but I do not recall being tested...
I have a close friend who has been addicted to marijuana for a long time, she also smoked during her pregnancy and no they did not test her for it when she gave birth. I don't know much on the effects of marijuana use during pregnancy but I strongly suggest that you look into that for the benefit of the baby. I know that she breastfed for quite a while, continuing to pass the drug onto her child. Our sons are the same age and have been friends since infancy. I can't say for sure where it came from, but her son struggles a great deal with emotional problems. He's an exceptionally bright (almost gifted) child, however, he does not do well academically because he can not control his emotions. He talks often about hating himself and killing himself, he has done this since pre-school age. So, while you most likely won't be tested for marijuana use, I believe you should be concerned with, if any, the effects that the usage may have on the baby. Good luck to you.