Subject: Re: [PATCH 01/11] test-lib: catch misspelt 'test_expect_successo'

From: Jeff King <[email-masked]>
Date: Thu, 26 Mar 2026 00:08:28 -0400

On Tue, Mar 24, 2026 at 11:21:04PM -0700, Junio C Hamano wrote:

>  # Test the binaries we have just built.  The tests are kept in
>  # t/ subdirectory and are run in 'trash directory' subdirectory.
> +
> +set -e

This causes failures in t0005 and t3600 with dash, but not bash.

It looks like the suppression of "-e" on the left-hand-side of an && is
different when there is command substitution in play:

  $ dash -c 'OUT=$( ((yes; echo $? 1>&3) | :) 3>&1) && echo out=$OUT'
  out=141

  $ dash -ec 'OUT=$( ((yes; echo $? 1>&3) | :) 3>&1) && echo out=$OUT'
  out=

whereas with bash, both produce 141.

The idea is that $OUT becomes the exit status of "yes" here, and we are
expecting to see SIGPIPE. With "-e" in effect, the failing "yes" will
terminate before we echo $?.

To demonstrate the effect as we build it up from smaller pieces:

  # produces 141, SIGPIPE from yes
  dash -c '((yes; echo $? 1>&3) | :) 3>&1'

  # produces nothing, "-e" kills subshell after yes fails
  dash -ec '((yes; echo $? 1>&3) | :) 3>&1'

  # produces 141 (and "ok"), as the && suppresses -e
  dash -ec '((yes; echo $? 1>&3) | :) 3>&1 && echo ok'

  # produces "out="; the $() makes us forget that we're on LHS of &&
  dash -ec 'OUT=$( ((yes; echo $? 1>&3) | :) 3>&1) && echo out=$OUT'

The actual failing code in t0005 is:

  OUT=$( ((large_git; echo $? 1>&3) | :) 3>&1 ) &&
  test_match_signal 13 "$OUT"

and the one in t3600 is similar. I guess you could do:

diff --git a/t/t0005-signals.sh b/t/t0005-signals.sh
index afba0fc3fc..0bf1f16750 100755
--- a/t/t0005-signals.sh
+++ b/t/t0005-signals.sh
@@ -42,7 +42,7 @@ test_expect_success 'create blob' '
 '
 
 test_expect_success !MINGW 'a constipated git dies with SIGPIPE' '
-	OUT=$( ((large_git; echo $? 1>&3) | :) 3>&1 ) &&
+	OUT=$( ((large_git || echo $? 1>&3) | :) 3>&1 ) &&
 	test_match_signal 13 "$OUT"
 '

That neglects to echo $? when large_git surprisingly succeeds, but that
would mean $OUT is empty, which would cause the test to (correctly)
fail. I kind of hate it, though.

-Peff