Then you must have mistakenly replied to the wrong thread? If you are in a position where you can introduce fx, then you are also in a position to introduce tes

Then you must have mistakenly replied to the wrong thread? If you are in a position where you can introduce fx, then you are also in a position to introduce testing, and testing will already force testable code. If fx can help your code, great, but that's orthogonal to the discussion.