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

[Eli Zaretskii <eliz@gnu.org>]

> From: Przemysław Wojnowski <esperanto@cumego.com>
> Date: Wed, 11 Nov 2015 22:08:49 +0100
> Cc: emacs-devel@gnu.org
> 
>  > The style is quite different: where CONTRIBUTE is about information
>  > for contributors, the suggested change, with the exception of its
>  > first sentence, is a motivational text that has no informational value
>  > for contributors.
> I tend to agree that my style of writing is different than the rest of
> the document and is a place to improve. That's why I've sent it here.

I didn't object to your posting it here.  You asked for a review, and
I tried to provide it.

>  > More importantly, I disagree with your posit that writing tests is a
>  > good way of learning about Emacs internals.
> Did you write this based on your experience?

Yes, of course.  Why do you ask?

> It *is* very good way to learn about a project and, in many companies,
> is used to introduce new developers. (I do that every time and after
> sometime devs tell me that it is a good introduction, because project
> at the beginning were to big and overwhelming to them.)

Then I guess we will have to agree to disagree about this.

>  > Best tests are written by looking at the spec alone,
>  > because looking at the implementation will bias you when
>  > you write the test.  That's why tests should ideally be
>  > written by someone who is not the implementor.
> Ideally yes. And new contributors are very close to this ideal, because
> they didn't implement the code and have docs as specs.

If they go by the spec and the docs, their tests will be very good, I
agree.  But that's not an efficient way of learning the internals: for
that, you need to study the implementation, not the docs and the
requirements.

>  >  I'm sure you are
>  > familiar with the TDD methodology, whose strong point is precisely
>  > that you write tests before implementing anything.
> "Reality check:" we already have code base. ;-)

How does this argument help in advancing this discussion?