No Drama. I installed the latest UPS version into my Heating System/Well Monitor enclosure. I was pretty confident that I would work as designed so the only testing that I employed was to disconnect the wall adapter and then reconnected after a couple of seconds. The system didn't show any signs of distress and the log file registered the event:

2019-07-28 12:48:05,181 INFO     Enabled

2019-07-28 13:17:12,174 INFO     Power has failed

2019-07-28 13:17:15,181 INFO     Power is good

2019-07-28 13:17:16,185 INFO     Returning to normal status

2019-08-15 23:42:13,903 INFO     Power has failed

2019-08-15 23:42:14,909 INFO     Power is good

2019-08-15 23:42:14,912 INFO     Returning to normal status

2019-08-16 09:39:35,642 INFO     Power has failed

2019-08-16 09:39:44,661 INFO     powerfail iminent...shutting down the Pi!

2019-08-16 09:40:47,147 INFO     Enabled

Since I installed it, on 2019-07-28, there have been two power loss events recorded in the log. One event was only a second in duration so the UPS did not have to shut down the RPi (but my hot tub and range needed some service.) The second outage was long enough to cause a shutdown, but it performed as designed. 

At this point I'm marking this project as completed.