v3, 8 partsfix test failure with busybox

Despite non-compiance from busybox's sh(1), grep(1), diff(1), find(1) Alpine Linux is still a popular choice for container these days.

Fix false-positive failure in testsuite when run in Alpine Linux.

Đoàn Trần Công Danh (8):
  t4061: use POSIX compliant regex(7)
  test-lib-functions: test_cmp: eval $GIT_TEST_CMP
  t5003: drop the subshell in test_lazy_prereq
  t5003: skip conversion test if unzip -a is unavailable
  t5616: use rev-parse instead to get HEAD's object_id
  t7063: drop non-POSIX argument "-ls" from find(1)
  t4124: fix test for non-compliant diff(1)
  t5703: feed raw data into test-tool unpack-sideband

 t/helper/test-pkt-line.c           |  2 +-
 t/t4061-diff-indent.sh             |  2 +-
 t/t4124-apply-ws-rule.sh           |  6 ++++++
 t/t5003-archive-zip.sh             | 24 ++++++++++++------------
 t/t5616-partial-clone.sh           |  2 +-
 t/t5703-upload-pack-ref-in-want.sh |  5 +----
 t/t7063-status-untracked-cache.sh  |  2 +-
 t/test-lib-functions.sh            |  2 +-
 8 files changed, 24 insertions(+), 21 deletions(-)

Range-diff against v2:
1:  34f96548de = 1:  088905ab6f t4061: use POSIX compliant regex(7)
2:  50f46986a6 = 2:  691d9d47ba test-lib-functions: test_cmp: eval $GIT_TEST_CMP
3:  8719a07753 = 3:  759a589b83 t5003: drop the subshell in test_lazy_prereq
4:  457eecaf9b = 4:  e5b09c290c t5003: skip conversion test if unzip -a is unavailable
5:  d3bc855e17 = 5:  1b8740018c t5616: use rev-parse instead to get HEAD's object_id
6:  64472ec3bc ! 6:  abb21b9e51 t7063: drop non-POSIX argument "-ls" from find(1)
    @@ Commit message
         However, `-ls` flag isn't required by POSIX's find(1), and
         busybox(1) doesn't implement it.
     
    -    From the original conversation, it seems like find(1) with "-type d"
    -    could trigger enough "lstat(2)" to ask FreeBSD update mtime.
    -
    -    Use only filter "-type d" for now.
    +    Use "-exec ls -ld {} +" instead.
     
         Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>
     
    @@ t/t7063-status-untracked-cache.sh: GIT_FORCE_UNTRACKED_CACHE=true
      
      sync_mtime () {
     -	find . -type d -ls >/dev/null
    -+	find . -type d >/dev/null
    ++	find . -type d -exec ls -ld {} + >/dev/null
      }
      
      avoid_racy() {
7:  51df6dd12d ! 7:  0502171f0f t4124: fix test for non-compliant diff(1)
    @@ Commit message
         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.
    +    HP-UX's diff(1) doesn't understand "-u" as of now.
     
    -    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
    +    Workaround this problem by checking "diff -u" output,
         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: test_fix () {
      
      	# find touched lines
      	$DIFF file target | sed -n -e "s/^> //p" >fixed
    -+	# busybox's diff(1) output unified format
    ++	# busybox's diff(1) doesn't output normal format
     +	if ! test -s fixed; then
    -+		$DIFF file target |
    ++		$DIFF -u file target |
     +		grep -v '^+++ target' |
     +		sed -e "/^+/s/+//" >fixed
     +	fi
8:  843c7f66d9 = 8:  8689e03400 t5703: feed raw data into test-tool unpack-sideband

BRE interprets `+` literally, and `\+` is undefined for POSIX BRE, from: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_03_02

This test is failing with busybox sed, the default sed of Alpine Linux

We have 2 options here:

- Using literal `+` because BRE will interpret it as-is, or
- Using character class `[+]` to defend against a sed that expects ERE

ERE-expected sed is theoretical at this point, but we haven't found it, yet. And, we may run into other problems with that sed. Let's go with first option and fix it later if that sed could be found.

Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>
---
 t/t4061-diff-indent.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Shell recognises first non-assignment token as command name. With /bin/sh linked to either /bin/bash or /bin/dash, `cd t/perf && ./p0000-perf-lib-sanity.sh -d -i -v` reports:

Using `eval` to unquote $GIT_TEST_CMP as same as precedence in `git_editor`.

Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>
---
 t/test-lib-functions.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

test_lazy_prereq will be evaluated in a throw-away directory.

Drop unnecessary subshell and mkdir.

Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>
---
 t/t5003-archive-zip.sh | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

Alpine Linux's default unzip(1) doesn't support `-a`.

Skip those tests on that platform.

Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>
---
 t/t5003-archive-zip.sh | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

Only HEAD's object_id is necessary, rev-list is an overkill.

Despite POSIX requires grep(1) treat single pattern with <newline> as multiple patterns. busybox's grep(1) (as of v1.31.1) haven't implemented it yet.

Use rev-parse to simplify the test and avoid busybox unimplemented features.

Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>
---
 t/t5616-partial-clone.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

POSIX's diff(1) requires output in normal diff format. However, busybox's diff's output is written in unified format.

HP-UX's diff(1) doesn't understand "-u" as of now.

Workaround this problem by checking "diff -u" output, 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(+)

Since commit 6b7728db81, (t7063: work around FreeBSD's lazy mtime update feature, 2016-08-03), we started to use ls as a trick to update directory's mtime.

However, `-ls` flag isn't required by POSIX's find(1), and busybox(1) doesn't implement it.

Use "-exec ls -ld {} +" instead.

Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>
---
 t/t7063-status-untracked-cache.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

busybox's sed isn't binary clean. Thus, triggers false-negative on this test.

We could replace sed with perl on this usecase. But, we could slightly modify the helper to discard unwanted data in the beginning.

Fix the false negative by updating this helper.

Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>
---
 t/helper/test-pkt-line.c           | 2 +-
 t/t5703-upload-pack-ref-in-want.sh | 5 +----
 2 files changed, 2 insertions(+), 5 deletions(-)