"I've heard about an ATB Test. What is it?"
An ATB Test stands for Ability-to-Benefit Test. Not all colleges accept ATB Tests, but some do, and what it allows you to do is to attend college without a high school diploma or GED. Not only does it allow you entry into the school, it allows you to obtain FA.
The tests themselves are made by publishers, and are administered by (according the the FSA Handbook) a certified official which may include "high school guidance counselors, test and measurement experts, human resource development professionals, qualified professional educators, or regional Armed Forces Command staff who are experts in education, training, and human resource development." The test itself must be administered properly for it to be used. For an administrator of the test to be certified, they must be certified by the state or by the publisher of the test used.
If a school or its employee(s) affect the outcome of test scores in any way, or if the test wasn't administered independently of the school, then the school is responsible for returning any FA funds. So, basically, if anything is out of the ordinary, then the student isn't eligible for FA funds.
However, a new change is on the horizon beginning July 1, 2012. The ATB Test can still be used as an entrance into college, but the student will not be eligible to receive any FA funds. In order to be eligible for FA funds, the student will have to have a high school diploma, a GED, or pass a state-recognized home school program.
So, the short answer is go ahead and get your diploma, GED, or finish home schooling. You won't get FA without one of them!
For more information about ATB Tests, check out the 2011-12 FSA Handbook (available online only at this point), Volume 1, Chapter 1, pages 8-11.