Re: [PATCH] CONTRIBUTE - writing tests for understanding internals

["Andreas Röhler" <andreas.roehler@online.de>]

  On 12.11.2015 21:03, Stephen Leake wrote:
> Eli Zaretskii<eliz@gnu.org>  writes:
>
>>> Date: Thu, 12 Nov 2015 08:16:47 +0100
>>> From: Andreas Röhler<andreas.roehler@online.de>
>>> CC: Eli Zaretskii<eliz@gnu.org>
>>>
>>>    On 11.11.2015 16:40, Eli Zaretskii wrote:
>>>> [ ... ]
>>>> written by someone who is not the implementor.  I'm sure you are
>>>> familiar with the TDD methodology, whose strong point is precisely
>>>> that you write tests before implementing anything.
>>> Hmm, looks for me like TDD established a kind of religion too.
>>> How to write tests without knowing the types?
>> The API should be defined when you write the tests, but the
>> implementation doesn't yet exist.
> I use this style of development myself.
>
> In reality, after you get started, the tests evolve along with the code.
> But for every change, you change the tests first.
>
> Often, after a change is implemented, it affects other tests that you
> did not change. Then you have to decide whether that is ok, and fix the
> tests to match, or if the code needs to be changed more to preserve the
> previous behavior.
>
> I have lots of commits of tests in my NASA code that say "match code
> change".
>

Interesting.

After all, might it be more effective to do everything with tests in 
mind, but be carefully, kind of lazy, when investing into?

Well, there is still another thing with TDD: it's irrational by its 
definition. Tests drive nothing, whilst their results come from behind.
Tests luck direction and decision, which must precede them.