Re* [RFH] adding test coverage for contrib/ in CI jobs

[Junio C Hamano <gitster@pobox.com>]

Junio C Hamano <gitster@pobox.com> writes:

> Unfortunately, this seems to reveal existing other problems with
> subtree tests (t7900), in addition to diff-highlight tests (t9400)
> in various configurations.
>
>   https://github.com/git/git/actions/runs/21617099884
>
> This Ci run is near the tip of 'seen', so there may be breakages
> attributable to new topics in flight, but I suspect that many of
> them are already in 'master', noticed by nobody because nobody ran
> these tests in these configurations (like "breaking changes",
> "sha256", "leaks", "reftable", "asan").
>
> I didn't look into the details of any of these (yet).

I didn't look into CI failures but spotted an easy one by
eyeballing.  As we seem to be lacking a dedicated subsystem
maintainer for this tool, I am CCing those who have touched this
test file during the past 24 months, plus our resident reftable
expert.

----- >8 -----
Subject: subtree: allow testing with reftable backend

"git subtree" (in contrib/) comes with its own test script, which
has this line

    defaultBranch=$(sed "s,ref: refs/heads/,," "$test_count/.git/HEAD")

that assumes that you can read from .git/HEAD as a regular text file
and you'd find a textual symref in reffiles backend.

Not necessarily.

    make && cd contrib/subtree && 
    GIT_TEST_DEFAULT_REF_FORMAT=reftable make test

fails due to this.  Use "git symbolic-ref" instead to read the value
of the symref.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 contrib/subtree/t/t7900-subtree.sh | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git c/contrib/subtree/t/t7900-subtree.sh w/contrib/subtree/t/t7900-subtree.sh
index 316dc5269e..344956e72e 100755
--- c/contrib/subtree/t/t7900-subtree.sh
+++ w/contrib/subtree/t/t7900-subtree.sh
@@ -1597,7 +1597,8 @@ test_expect_success 'push split to subproj' '
 
 test_expect_success 'subtree descendant check' '
 	subtree_test_create_repo "$test_count" &&
-	defaultBranch=$(sed "s,ref: refs/heads/,," "$test_count/.git/HEAD") &&
+
+	defaultBranch=$(git -C "$test_count" symbolic-ref --short HEAD) &&
 	test_create_commit "$test_count" folder_subtree/a &&
 	(
 		cd "$test_count" &&