Re: [PATCH v2] sha1-file: test the error behavior of alt_odb_usable()

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

Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:

> I'll leave it up to you if you want to queue just the test patch or drop

As I said in a separate message, I think it is good to make sure
that fsck does not crash.  I do not think it is good to grep in its
output.

> it. I figured I'd re-send just that since I figured just fixing the
> blindspot of the current behavior would be a good thing on its own, not
> as an endorsement of the current behavior, just a "this is the current
> known behavior" regression test.

If the behaviour is undesirable one, we could document the current
"breakage" with "test_expect_failure", whether we plan to fix it
immediately.  It is OK if readers cannot tell between a bug that is
expected to stay forever with us, or a bug that somebody is actively
working on.  

But unfortunately, there is no separate "test_merely_documenting",
that is different from "test_expect_success", so even if we claim
"this is not an endorsement, but is merely documenting the current
behaviour" when we add such a test, there is no way for future
readers to tell between the two, short of going back to "git blame"
and seeing the log message.

For that reason, I do not think it is a good practice to document
the "current behaviour that happens to be" the same way as "the
behaviour we desire" in test_expect_success.