[PATCH] t0000: disable GIT_TEST_FAIL_PREREQS in sub-tests

[Jeff King <peff@peff.net>]

On Tue, Apr 28, 2020 at 08:52:34AM +0200, Son Luong Ngoc wrote:

> Running t0000 with GIT_TEST_FAIL_PREREQS=true is failing.
> 
> > GIT_TEST_FAIL_PREREQS=true ./t0000-basic.sh
> t/./t0000-basic.sh:836: error: not ok 45 - 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

I think the patch below is the right fix.

-- >8 --
Subject: [PATCH] t0000: disable GIT_TEST_FAIL_PREREQS in sub-tests

The test added by 477dcaddb6 (tests: do not let lazy prereqs inside
`test_expect_*` turn off tracing, 2020-03-26) runs a sub-test script
that traces a test with a lazy prereq, like:

  test_have_prereq LAZY && echo trace

That won't work if GIT_TEST_FAIL_PREREQS is set in the environment,
because our have_prereq will report failure, and we won't run the echo
at all.

We could work around this by avoiding the &&-chain, but we can
fix this and any future tests at once by unsetting that variable for our
sub-tests. These are meant to be controlled environments where we test
the test-suite itself; the outer test snippet should be in charge of the
sub-test environment, not whatever mode the user happens to be running
in.

Reported-by: Son Luong Ngoc <sluongng@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
---
 t/t0000-basic.sh | 1 +
 1 file changed, 1 insertion(+)

diff --git a/t/t0000-basic.sh b/t/t0000-basic.sh
index b859721620..f58f3deaa8 100755
--- a/t/t0000-basic.sh
+++ b/t/t0000-basic.sh
@@ -98,6 +98,7 @@ _run_sub_test_lib_test_common () {
 		export TEST_DIRECTORY &&
 		TEST_OUTPUT_DIRECTORY=$(pwd) &&
 		export TEST_OUTPUT_DIRECTORY &&
+		sane_unset GIT_TEST_FAIL_PREREQS &&
 		if test -z "$neg"
 		then
 			./"$name.sh" "$@" >out 2>err
-- 
2.26.2.827.g3c1233342b