Subject: Re: [PATCH v4] branch: introduce --show-current display option

From: Eric Sunshine <[email-masked]>
Date: Wed, 17 Oct 2018 06:39:02 -0400

On Wed, Oct 17, 2018 at 6:18 AM Johannes Schindelin <[email-masked]> wrote:
> I realized yesterday that the &&-chain linting we use for every single
> test case takes a noticeable chunk of time:
>
>         $ time ./t0006-date.sh --quiet
>         real    0m20.973s
>         $ time ./t0006-date.sh --quiet --no-chain-lint
>         real    0m13.607s
>
> My suspicion: it is essentially the `(exit 117)` that adds about 100ms to
> every of those 67 test cases.

The subshell chain-linter adds a 'sed' and 'grep' invocation to each test which doesn't help. (v1 of the subshell chain-linter only added a 'sed', but that changed with v2.)

> With that in mind, I would like to suggest that we should start to be very
> careful about using subshells in our test suite.

You could disable the subshell chain-linter like this if you want test the (exit 117) goop in isolation:

--- 8< ---
diff --git a/t/test-lib.sh b/t/test-lib.sh
index 3f95bfda60..48323e503c 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -675,8 +675,7 @@ test_run_ () {
 		trace=
 		# 117 is magic because it is unlikely to match the exit
 		# code of other programs
-		if $(printf '%s\n' "$1" | sed -f "$GIT_BUILD_DIR/t/chainlint.sed" | grep -q '?![A-Z][A-Z]*?!') ||
-			test "OK-117" != "$(test_eval_ "(exit 117) && $1${LF}${LF}echo OK-\$?" 3>&1)"
+		if test "OK-117" != "$(test_eval_ "(exit 117) && $1${LF}${LF}echo OK-\$?" 3>&1)"
 		then
 			error "bug in the test script: broken &&-chain or run-away HERE-DOC: $1"
 		fi
--- 8< ---