On Thu, Apr 22 2021, Đoàn Trần Công Danh wrote:

On 2021-04-21 16:32:40-0700, Junio C Hamano [off-list ref] wrote:

quoted

Eric Sunshine [off-list ref] writes:

quoted

On Wed, Apr 21, 2021 at 12:55 PM Eric Sunshine [off-list ref] wrote:

quoted

    count_ls_files 5 -s &&
    count_ls_files 3 -u &&
    count_ls_files 1 -u one~HEAD &&
    ...

The nice thing about having a helper function is that it can clean up
after itself by not leaving a new file lying around, thus you wouldn't
have to make adjustments to the expected number of untracked files (as
mentioned in the commit message). If this is the sort of thing which
comes up often enough (if there are more such cases beyond the two
scripts you changed in this series), then it might make sense to
promote the helper function to test-lib-functions.sh.

The frequency with which this idiom crops up with commands beyond
git-ls-files suggests the more general solution of supporting it
directly in test-lib-functions.sh for any command. For instance:

    test_cmd_line_count = 3 git ls-files -u &&

Or, perhaps, a new mode of test_line_count():

    test_line_count = 3 -c git ls-files -u &&

Hm, I'm not sure how would we implement such mode:

* Will we run such command in a subprocess and and pipe to "wc -l"
  directly to avoid a temporary file, but we will lose the exit code
  of running command in process?

Just use a tempfile.

* Will we run in a separated chain? Thus, a temporary file would be
  created, skimming over test-lib-functions.sh, I couldn't find any
  convention for creating such files, except for specific use cases,
  let's say "*.config".

Yeah we happen not to have one of those in test-lib-functions.sh, but a
bunch of helpers create those.

* Another clever hacks that I don't know *shrug*

quoted

That looks nice on paper, but may be going too far.

We may want to count the lines in the error message,

Let's assume that we solve above puzzle.

Count the lines in the error messages is not too hard to be imagined,
let's say by -c2 or something like that.

quoted

or we may want
to count the lines after filtering the output with pipe.

However, when it involved a pipe, things becomes complicated.

Yes, there's no portable way to both stream stdout/stderr in the correct
order and to intercept it. You'd need a mkfifo. See also how the "--tee"
mode works (i.e. they're squashed).

quoted

A test file that is dedicated to test ls-files with a file local
helper "count_ls_files" smells like a better place to stop, at least
to me.

Hence, I'll stick with local help "count_ls_files" for now.

Here's an implementation that works, sans the fancy opts parsing etc. I
just use -1 for "don't care". You can see "test_commit" etc. for how to
do that.

It doesn't emit output, but that's just a matter of re-cat-ing the
relevant files.

Yes we wouldn't have combined output when you do that, but I don't think
we care, you can chain this thing, and most thing that would do so would
only care about piping stdout/stderr to their own files anyway, and not
that we emit one line of stdout, then another of stderr, another of
stdout etc.

diff --git a/t/t6402-merge-rename.sh b/t/t6402-merge-rename.sh
index 425dad97d54..c7251102a3d 100755
--- a/t/t6402-merge-rename.sh
+++ b/t/t6402-merge-rename.sh

@@ -154,14 +154,10 @@ test_expect_success 'pull conflicting renames' \
 	git reset --hard &&
 	git show-branch &&
 	test_expect_code 1 git pull . blue &&
-	git ls-files -u A >a.stages &&
-	test_line_count = 1 a.stages &&
-	git ls-files -u B >b.stages &&
-	test_line_count = 1 b.stages &&
-	git ls-files -u C >c.stages &&
-	test_line_count = 1 c.stages &&
-	git ls-files -s N >n.stages &&
-	test_line_count = 1 n.stages &&
+	test_line_count_command = 1 0 git ls-files -u A &&
+	test_line_count_command = 1 0 git ls-files -u B &&
+	test_line_count_command = 1 0 git ls-files -u C &&
+	test_line_count_command = 1 0 git ls-files -s N &&
 	sed -ne "/^g/{
 	p
 	q

diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index b823c140271..10e3cbe0d47 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh

@@ -817,6 +817,24 @@ test_line_count () {
 	fi
 }
 
+test_line_count_command () {
+	local op=$1
+	local ocnt=$2
+	local ecnt=$3
+	shift 3
+	"$@" 2>cnt.err >cnt.out
+	local exit_code=$?
+	if test "$ocnt" -gt -1
+	then
+		test_line_count "$op" "$ocnt" cnt.out
+	fi &&
+	if test "$ecnt" -gt -1
+	then
+		test_line_count "$op" "$ecnt" cnt.err
+	fi &&
+	return "$exit_code"
+}
+
 test_file_size () {
 	test "$#" -ne 1 && BUG "1 param"
 	test-tool path-utils file-size "$1"