TDD is BS?

[Szymon Gatner]

On Wednesday, 19 June 2013 at 21:54:04 UTC, Walter Bright wrote:
> On 6/19/2013 4:01 AM, Szymon Gatner wrote:
>> This is not strictly D related but I am very curious about D's 
>> community opinion
>> on the points made by non other than Jim Coplien here:
>
>
> TDD strikes me as an ad-hoc way of constructing code, and is a 
> poor substitute for thinking about the problem as a whole. For 
> example, I don't really see how getting a square root function 
> to pass its test cases is going to lead one to implementing one 
> of the classic algorithms for computing square roots. I don't 
> see how TDD for a compiler will lead one to rediscover what is 
> known about the best way to organize the logic of a compiler.
>
> TDD is "curve fitting" which is what one does when one has no 
> understanding.
>
> D's support of unit testing is not an endorsement of TDD.

Point of TDD for a square root function would be to create a good 
API for getting a square root of a number. Implementation is just 
a detail. Good class design is way harder to achieve then correct 
implementation. Libraries become unusable in time not because 
they did what they did wrong but because they were badly 
structured / designed.

TDD claims to help with this by forcing you to code client code 
first (the test) which arguably leads to better decoupling of 
components. You don't have to split components for reuse later 
because they are already being used in unrelated contexts in 
tests.