We've found that either starting a New Meeting from the Zoom Rooms Controller or joining/calendaring a no-fixed-time testing meeting does the trick.
You can run an audio echo test from Settings->General on the Zoom Rooms Controller or virtual controller, although this is generally done every night and doesn't capture connection quality, video quality, etc.
There is no 'Test Call' functionality for Zoom rooms, but this would be a great Feature Request - please be sure to submit this formally to Zoom Support. One of the big benefits of this feature would be that the test could/should not show as a meeting on the room's calendar the way a 'New Meeting' would.
**Generally speaking, we have found Zoom's reporting/dashboarding to be vague, and in many cases, inaccurate. A Room Test function would likely rely on the same metrics.