Right, but the average case over 40k lines of code will be somewhere in the middle - some functions/ methods/ whatever will require 2 tests, and some will require 1000s. Of course I realise your example is intended to be simplistic to the extreme, but few realistic conditions have such narrow scope.

Test/LOC ratio is at least as useful a metric as LOC itself - it provides some guide as to the complexity of a real project (as opposed to twee little 'yes but *this* code is a million lines all printing "Hello World"' projects just to prove my statement wrong ;) )

Of course I didn't expect any response to say "You have it exactly right" or "No, you must be doing twice as many tests as LOC", I'm just after a general "am I on the right path, or am I spinning wheels writing tests that will eventually be duplicated in some way".