I have this in as a “how do I do this?” question over here: How to disable test parallelization *just* for system tests?
But it’s actually kind of a newbie WTF as welll. I’m running the out-of-box
rails generate scaffold-generated system tests for a resource using chromedriver, and at least 50% of the time one or more tests fail. Running with
PARALLEL_WORKERS=1 fixes it.