Basically, a Cognitive Ability Test is a test of your thinking power. Through puzzles, riddles, story problems, and various timed activities as well as comprehension assignments and reading and mathematics exams, a cognitive ability test can show the state of your mind. Of course, this test is not an absolute test of intelligence. Cognitive ability varies over time, and even from moment to moment, so the Cognitive Ability Test doesn't really show your full intelligence or mental capacity, however it can provide a fairly good estimation about current mental activity.
There is a fair bit of controversy surrounding mental tests such as the IQ test and the Cognitive Ability Test. Many people have many different oppinons about the meaning and nature of intelligence. Some people feel that intelligence is something that can be tested by the cognitive ability test, and is basically a measure of your brains current ability to quickly solve various problems and puzzles. Others feel that a Cognitive Ability Test has little or nothing to do with intelligence, since intelligence is a measure not of what your brain currently can do, but of how much information it is theoretically able to accommodate. Other people believe that a cognitive ability test only really measures how well you are able to do in a testing environment, and that true intelligence can only be measured using a combination of factors, including observing the subject in their natural environment to see how well they do at their favorite chosen activities when they are at their most relaxed. But the Cognitive Ability Test does seem to provide a fairly good feel of how well most people can perform at intellectual tasks.