If you have an old fixture that has not been in use, or is not working properly, checking it for electrical safety is a wise idea for at least peace of mind. Old brittle wiring and old sockets should be replaced if not in good condition.
Our shop is not certified by Underwriter Laboratories. However, if you have a project that requires a UL listing, that is available for an additional nominal fee. We can also get a similar safety listing from City of Los Angeles testing labs. The exception is fixtures (mostly flush mount) that are purchased and already come with the UL sticker.