"guess it's just as well that Chapter 18 suggests testing everything before you deploy it! ;-)"
It is kind of far-fecthed to talk about testing here. The best practice is to find "bugs" as earlier as possible, the later they are found/fixed, the higher the cost is.
The particular bad practice that we are discussing in this case, can be easily spotted as early as specification review (if the process requires one to document such details), or at least during peer code review. If a simple issue like this can actually pass all the guarding processes and go as far as testing, the processes should be reviewed.
Update: Read TheDamian's reply, now I have seen that big ;-) Okay, my fault, please ignore my first sentence in this post.