Re: Histogram diff, libgit2 enhancement, libgit2 => git merge (GSOC)

From: Junio C Hamano <gitster@pobox.com>
Date: Mar 22, 2011, 19:18 UTC
Message-ID: <7vtyevj753.fsf@alter.siamese.dyndns.org>
In-Reply-To: <20110322184737.GB22534@sigill.intra.peff.net>

Jeff King <peff@github.com> writes:

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> It may also be necessary to use a mixture of git and libgit2 commands to
> finish tests. For example, a test which is really about checking "log"
> might use "commit", but "commit" hasn't been implemented yet. But it is
> still useful information if we cheat and use regular git's "commit", but
> test the libgit2 log command.

Absolutely, and I don't even think that is "cheating"; it is merely a natural way to work incrementally.

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> As far as which commands to start with, I would start with plumbing
> commands like "update-index", "commit-tree", "update-ref", "rev-list",
> etc.  Those are basic building blocks that have reasonably simple
> interfaces, and they're easy to test. And once you start, I think it
> will become more obvious where to go next (because some of the commands
> build on the results of others).
>
>> This probably will lead to some test suite changes, is it truth?

Some tests _might_ depend on implementation detail that we would rather not, but I don't think there are too many of them, unless you count the stuff that use "test-<something>" helper binary that link with libgit.a to make direct calls to the internal. I would suggest to consider a failure an uncovered bug in the new implementation by default, and discuss the tests that do depend on the implementation detail of C git on case-by-case basis to be fixed.