Living a healthy lifestyle can help an HIV positive person live a longer, and healthier life. If a person gets tested, and they find out that they have HIV, they are more likely to seek medical treatment sooner. Generally speaking, the sooner that treatment begins, the more effective it is at slowing down the progression of the disease. In cases such as this, the person may wish to seek counseling to help them deal with that stress. For persons at little or no risk of infection, testing is a waste of time and money.
Testing is best suited for persons at a realistic risk of infection.
If a person gets tested, and they find out that they have HIV, this can make a person very depressed, and understandably so. However, there are many support groups and counseling services, to help a person cope with their HIV positive status. If you have put yourself at risk of infection, I strongly suggest you consider getting tested, to determine whether you are infected or not. By the way, these same pros and cons of testing, apply to other health problems as well. If a person has put themselves at risk for other sexually transmitted diseases, other bloodborne diseases, etc., testing for these other diseases is just as important.