The second method of earning college credits is called PLA or Prior Learning Assessment.
Some colleges allow you to receive college credit for job training, professional experience, or military training. All that is needed is a certificate, or any documentation that you received training in almost any field. The various areas pf training are quite diverse. Military training is one of the most acceptable. If you finished a course needed to qualify for a job and received a certificate or diploma that is usually sufficient to credits. Other certificates can be earned just for completing a course in a field of personal interest. I received one credit just by presenting my SCUBA diving certificate. Others include CPR training, off college course in IT or related subjects. A certificate that proves you took an hour course in MS Word or Excel, may work also.
The key is providing a certificate or other document proving that training was received.
There is no testing required. If you have a certificate, just ask a school counselor for instructions and requirements for presenting the document.