Though this may be immoral, I would recommend not notifying the uni of anything until or unless they flag this up and get in contact with you for a disciplinary meeting or some such; there is a small possibility you could get away with it. And if this is the case I'm sure you've learnt your lesson and won't do this again, if you have doubts about the assignment then arrange a meeting with the course organiser and/or the lecturer(s)! However, if they do detect the plagiarism and decide to open an investigation then your friend will definitely be notified about it and will also be investigated for their role in the offence.