Re: [PATCH v3 1/4] t1400: avoid touching refs on filesystem

The testcase t1400 exercises the git-update-ref(1) utility. To do so,
many tests directly read and write references via the filesystem,
assuming that we always use loose and/or packed references. While this
is true now, it'll change with the introduction of the reftable backend.

Convert those tests to use git-update-ref(1) and git-show-ref(1) where
possible. As some tests exercise behaviour with broken references and
neither of those tools actually allows writing or reading broken
references, this commit doesn't adjust all tests.

Signed-off-by: Patrick Steinhardt <redacted>
---
 t/t1400-update-ref.sh | 72 +++++++++++++++++++++++--------------------
 1 file changed, 39 insertions(+), 33 deletions(-)

diff --git a/t/t1400-update-ref.sh b/t/t1400-update-ref.sh
index 4c01e08551..d7a57488ed 100755
--- a/t/t1400-update-ref.sh
+++ b/t/t1400-update-ref.sh

@@ -188,27 +194,26 @@ test_expect_success "move $m (by HEAD)" '
 	test $B = $(git show-ref -s --verify $m)
 '
 test_expect_success "delete $m (by HEAD) should remove both packed and loose $m" '
-	test_when_finished "rm -f .git/$m" &&
+	test_when_finished "rm -f git update-ref -d $m" &&

 	git update-ref -d HEAD $B &&
 	! grep "$m" .git/packed-refs &&
-	test_path_is_missing .git/$m
+	test_must_fail git show-ref --verify -q $m
 '