Calling for help and assistance out there...

I was wondering if anyone out there can share with me what are the technical tests are are given to candidates during the on-site interview for Software Engineer position. It's because I'm helping a friend who will be attending the on-site interview soon and was told there will be technical test to be taken. I knew that it will be hard and tough given that I failed a couple of phone interview with them before. Any help given is very much appreciated...thank you in advance :)