Re: [PATCH v2 4/5] tests: do not let lazy prereqs inside `test_expect_*` turn off tracing

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

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Hi Junio,

On Wed, 25 Mar 2020, Junio C Hamano wrote:

> "Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>
> writes:
>
> > The `test_expect_*` functions use `test_eval_` and so does
> > `test_run_lazy_prereq_`. If tracing is enabled via the `-x` option,
> > `test_eval_` turns on tracing while evaluating the code block, and turns
> > it off directly after it.
> >
> > This is unwanted for nested invocations.
>
> Nice finding.

Heh. I found this ages ago, and mistook it for "all prereqs turn off
tracing" when I reported it, but Gábor pointed out that that is incorrect.

That was a long time ago, maybe even a year, and I finally used this patch
series as an excuse to finally dig deep on this.

> > As we will introduce just such a scenario with the GPG, GPGSM and
> > RFC1991 prereqs, let's fix that by introducing a variable that keeps
> > track of the current trace level: nested `test_eval_` calls will
> > increment and then decrement the level, and only when it reaches 0, the
> > tracing will _actually_ be turned off.
>
> Doesn't this explanation urge us to reorder these patches?  It
> sounds to me that it argues to have this step before 3/5.

Yes, that's where I had meant to put this patch. Sorry for the confusion.

> Other than that, both the explanation and the code look correctly
> done.  It looks to me that the surrounding code favors trailing "_"
> instead of leading one for private names, so we might want to rename
> the variable to $trace_level_ but that is minor.

Good point, I had missed that. Will be fixed in the next iteration.

Ciao,
Dscho

>
> Thanks.
>
> > Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> > ---
> >  t/t0000-basic.sh | 13 +++++++++++++
> >  t/test-lib.sh    |  6 ++++--
> >  2 files changed, 17 insertions(+), 2 deletions(-)
> >
> > diff --git a/t/t0000-basic.sh b/t/t0000-basic.sh
> > index 3e440c078d5..b8597216200 100755
> > --- a/t/t0000-basic.sh
> > +++ b/t/t0000-basic.sh
> > @@ -833,6 +833,19 @@ then
> >  	exit 1
> >  fi
> >
> > +test_expect_success 'lazy prereqs do not turn off tracing' "
> > +	run_sub_test_lib_test lazy-prereq-and-tracing \
> > +		'lazy prereqs and -x' -v -x <<-\\EOF &&
> > +	test_lazy_prereq LAZY true
> > +
> > +	test_expect_success lazy 'test_have_prereq LAZY && echo trace'
> > +
> > +	test_done
> > +	EOF
> > +
> > +	grep 'echo trace' lazy-prereq-and-tracing/err
> > +"
> > +
> >  test_expect_success 'tests clean up even on failures' "
> >  	run_sub_test_lib_test_err \
> >  		failing-cleanup 'Failing tests with cleanup commands' <<-\\EOF &&
> > diff --git a/t/test-lib.sh b/t/test-lib.sh
> > index 0ea1e5a05ed..dbf25348106 100644
> > --- a/t/test-lib.sh
> > +++ b/t/test-lib.sh
> > @@ -882,6 +882,7 @@ maybe_setup_valgrind () {
> >  	fi
> >  }
> >
> > +_trace_level=0
> >  want_trace () {
> >  	test "$trace" = t && {
> >  		test "$verbose" = t || test "$verbose_log" = t
> > @@ -895,7 +896,7 @@ want_trace () {
> >  test_eval_inner_ () {
> >  	# Do not add anything extra (including LF) after '$*'
> >  	eval "
> > -		want_trace && set -x
> > +		want_trace && _trace_level=$(($_trace_level+1)) && set -x
> >  		$*"
> >  }
> >
> > @@ -926,7 +927,8 @@ test_eval_ () {
> >  		test_eval_ret_=$?
> >  		if want_trace
> >  		then
> > -			set +x
> > +			test 1 = $_trace_level && set +x
> > +			_trace_level=$(($_trace_level-1))
> >  		fi
> >  	} 2>/dev/null 4>&2
>