I'm as grammatickler as the next guy, but I'd use "Since orElse...", because "asOrElse" sounds like Scala API.

As a former writing tutor, I mean, since I used to work at the writing clinic, I can't allow the following to stand or follow: "enforcing test coverage is worth considering."  But I agree with your inversion.

How about: "Since ..., the correctness of this branch of the code path should be checked by testing.  A code coverage tool can help enforce that this case is not overlooked during testing."

I feel like all of my weasel words just escaped from their cage.

I mean I feel as though they had.

My young daughter read, "He felt badly," in some book the other day, so I had to explain that, and then "The Arrow" on tv happened to say, "I felt badly."  Time to call in Word Girl!