Tests start the process, a basic mechanical aptitude test and a character test. They then schedule a ride-a-long so you can see what the scope of the work involves. This really helps eliminate any questions that may come up later. If you choose to proceed then you have a formal interview at the end of the ride-a-long and are told more specifics of the job. The ball is left in your court and you can say yes or no.

Phone interview with HR. Took mechanical test and personality test. Passed tests and spoke to manager right after. You do a full day ride along so you can experience the job in person. Called back for second interview. Get offer letter and start as soon as you can.