Re: [PATCH v2 3/4] test-lib-functions: add helper for trailing hash

From: SZEDER Gábor <szeder.dev@gmail.com>
Date: Dec 17, 2022, 17:37 UTC
Message-ID: <20221217173758.GB3411@szeder.dev>
In-Reply-To: <xmqqh6y0qfzg.fsf@gitster.g>

On Tue, Dec 13, 2022 at 09:55:47AM +0900, Junio C Hamano wrote:

Show 15 quoted lines

> SZEDER Gábor <szeder.dev@gmail.com> writes:
> 
> >> +	test_trailing_hash .git/index >hash &&
> >> +	echo $(test_oid zero) >expect &&
> >
> > Nit: test_oid zero >expect
> >
> >> +	test_cmp expect hash &&
> 
> Unfortunately they are not equivalent.
> 
> Usually we write these helpers to terminate their output with LF,
> relying on the fact that terminating LF will be dropped when used in
> a command substition, e.g. VAR=$(HELPER), but test_oid deviates from
> the pattern and does not give the terminating LF to its output.

Oh, indeed. But why does it omit the trailing LF?! Alas, 2c02b110da (t: add test functions to translate hash-related values, 2018-09-13) doesn't seem to mention anything about it. However, skimming through the output of

  git grep 'test_oid ' -- ':/t/*.sh'

it appears that all but three uses of 'test_oid' are in command substitutions, and those three exceptions are in t0000 checking that 'test_oid' actually works. So I don't see any benefit of omitting that trailing LF, but this and similar cases show its drawbacks.

  $ git grep 'echo $(test_oid ' -- ':/t/*.sh'
  t/t1302-repo-version.sh:        echo $(test_oid version) >expect &&
  t/t5313-pack-bounds-checks.sh:  echo $(test_oid oidfff) >file &&