I've also found then very straightforward to get up and running for testing
firmware on the @NordicTweets #nrf9160. I
use Ykush Yepkit https://www.yepkit.com/products/ykush for power-cycling the
devices between runs.

I am relying on UART output for controlling the test run and asserting some of
the expected behaviour, which is not reliable, UART output sometimes just stops.
So what I have on my to do list is to only assert cloud side state.