I went through one during my custody battle about 5 years ago. It was a long process. You are put through interviews by the psych, they do the picture test like you see on tv (they show you an ink blotch on a piece of paper and ask you what you see--I was told that most people view these pictures as sexual); and you take a test that is about 500 + questions that you have to answer. The questions range from basic questions they ask you in school regarding subjects like math, english, etc. to personal questions such as would you like to be a florist to logic questions about diagrams, etc. So, it covers a wide variety of areas of you as a "whole" being. The purpose of this testing is to test your intelligence, how you respond to certain things and situations, and how you perceive life. My involvement with the psych was about 6 months. When the testing and those 500+ question tests are completed and analyzed, the psych issues a very detailed report on the findings. My report was 18 pages long! You learn so many things good/bad about you as a whole person. These findings, no matter who you are, will show qualities in you that you never imagined--both good and bad. It can also show mental issues (everyone has some of these qualities, some mild/some extreme). Some qualities about you in these findings will be obvious to you, while others will shock you. Even if a doctor/psych has an evaluation, they to will get these results, so what I'm saying is that these tests are the same for EVERYONE, just different findings. At the end of the analysis, the psych will make a recommendation. The court may or may not take this recommendation into consideration. Personally, in my opinion, these tests are a waste of time and money, but this is how things are done by the court, so my advice to you is to cooperate fully keeping the welfare of your children the first and foremost number one priority. You do what you need to do for your kids. In the meantime, and this may sound corny, but here it goes: Keep your head on straight and make wise choices involving the welfare of your children. You cannot go wrong when you do right:) Please don't worry and stress yourself over the findings of this evaluation either. Every person who goes through this is scrutinized--that's the purpose of this procedure.
I hope this helps. Good luck,
M.