Re: [PATCHv2] add: ignore only ignored files

[Junio C Hamano <gitster@pobox.com>]

Jeff King <peff@peff.net> writes:

> ... Possibly because I do not know that those instructions
> are written down anywhere. We usually catch such things in review these
> days, but there are many inconsistent spots in the existing suite.

t/README has this

    Don't:

     - use '! git cmd' when you want to make sure the git command exits
       with failure in a controlled way by calling "die()".  Instead,
       use 'test_must_fail git cmd'.  This will signal a failure if git
       dies in an unexpected way (e.g. segfault).

       On the other hand, don't use test_must_fail for running regular
       platform commands; just use '! cmd'.

Though it can be improved by justifying "just use '! cmd'" further
with a bit of rationale (e.g. "We are not in the business of
verifying that world given to us sanely works."), I think the
current text is sufficient.

Do we refer to t/README from CodingGuidelines where we tell the
developers to always write tests to prevent other people from
breaking tomorrow what you did today?  If not, perhaps that is what
needs to be added.