Re: [PATCH v2 7/8] t4124: fix test for non-compliant diff(1)

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Mar 23, 2020, 13:58 UTC
Message-ID: <nycvar.QRO.7.76.6.2003231456200.46@tvgsbejvaqbjf.bet>
In-Reply-To: <10f39c3d30d13e9141f081f985a0620954cc7493.1584838148.git.congdanhqx@gmail.com>

Hi,

On Sun, 22 Mar 2020, Đoàn Trần Công Danh wrote:

Show 30 quoted lines

> POSIX's diff(1) requires output in normal diff format.
> However, busybox's diff's output is written in unified format.
>
> POSIX requires no option for normal-diff format.
>
> A hint in test-lib-functions::test_cmp said `diff -u` isn't available
> everywhere.
>
> Workaround this problem by assuming `diff(1)` output is unified
> if we couldn't make anything from normal-diff format.
>
> Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>
> ---
>  t/t4124-apply-ws-rule.sh | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/t/t4124-apply-ws-rule.sh b/t/t4124-apply-ws-rule.sh
> index 971a5a7512..075b1912be 100755
> --- a/t/t4124-apply-ws-rule.sh
> +++ b/t/t4124-apply-ws-rule.sh
> @@ -52,6 +52,12 @@ test_fix () {
>
>  	# find touched lines
>  	$DIFF file target | sed -n -e "s/^> //p" >fixed
> +	# busybox's diff(1) output unified format
> +	if ! test -s fixed; then
> +		$DIFF file target |
> +		grep -v '^+++ target' |
> +		sed -e "/^+/s/+//" >fixed
> +	fi

In my patches (which are too unpolished to contribute, I have not found time to clean them up in several years), I do this differently:

-- snip --
commit cb2f3a28dbf40b92d3d9ca0f3177cd5afb7c4196
Author: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Date:   Wed Jul 5 22:21:57 2017 +0200

    t4124: avoid using "normal" diff mode

    Everybody and their dogs, cats and other pets settled on using unified
    diffs. It is a really quaint holdover from a long-gone era that GNU diff
    outputs "normal" diff by default.

    Yet, t4124 relied on that mode.

    This mode is so out of fashion in the meantime, though, that e.g.
    BusyBox' diff decided not even to bother to support it. It only supports
    unified diffs.

    So let's just switch away from "normal" diffs and use unified diffs, as
    we really are only interested in the `+` lines.

    Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

diff --git a/t/t4124-apply-ws-rule.sh b/t/t4124-apply-ws-rule.sh
index 971a5a7512ac..133557b99333 100755
--- a/t/t4124-apply-ws-rule.sh
+++ b/t/t4124-apply-ws-rule.sh
@@ -51,7 +51,7 @@ test_fix () {
        apply_patch --whitespace=fix || return 1

        # find touched lines
-       $DIFF file target | sed -n -e "s/^> //p" >fixed
+       $DIFF -u file target | sed -n -e "3,\$s/^+//p" >fixed

        # the changed lines are all expected to change
        fixed_cnt=$(wc -l <fixed)
-- snap --

Food for thought?

Ciao,
Dscho

>
>  	# the changed lines are all expected to change
>  	fixed_cnt=$(wc -l <fixed)
> --
> 2.26.0.rc2.310.g2932bb562d
>
>
>