[PATCH 1/2] t1401: generalize reference locking

["Justin Tobler via GitGitGadget" <gitgitgadget@gmail.com>]

From: Justin Tobler <jltobler@gmail.com>

Some tests set up reference locks by directly creating the lockfile.
While this works for the files reference backend, reftable reference
locks operate differently and are incompatible with this approach.
Refactor the test to use git-update-ref(1) to lock refs instead so that
the test does not need to be aware of how the ref backend locks refs.

Signed-off-by: Justin Tobler <jltobler@gmail.com>
---
 t/t1401-symbolic-ref.sh | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/t/t1401-symbolic-ref.sh b/t/t1401-symbolic-ref.sh
index c7745e1bf69..bafe8db24df 100755
--- a/t/t1401-symbolic-ref.sh
+++ b/t/t1401-symbolic-ref.sh
@@ -105,10 +105,30 @@ test_expect_success LONG_REF 'we can parse long symbolic ref' '
 	test_cmp expect actual
 '
 
-test_expect_success 'symbolic-ref reports failure in exit code' '
-	test_when_finished "rm -f .git/HEAD.lock" &&
-	>.git/HEAD.lock &&
-	test_must_fail git symbolic-ref HEAD refs/heads/whatever
+test_expect_success PIPE 'symbolic-ref reports failure in exit code' '
+	mkfifo in out &&
+	(git update-ref --stdin <in >out &) &&
+
+	exec 9>in &&
+	exec 8<out &&
+	test_when_finished "exec 9>&-" &&
+	test_when_finished "exec 8<&-" &&
+
+	echo "start" >&9 &&
+	echo "start: ok" >expected &&
+	read line <&8 &&
+	echo "$line" >actual &&
+	test_cmp expected actual &&
+
+	echo "update HEAD refs/heads/foo" >&9 &&
+
+	echo "prepare" >&9 &&
+	echo "prepare: ok" >expected &&
+	read line <&8 &&
+	echo "$line" >actual &&
+	test_cmp expected actual &&
+
+	test_must_fail git symbolic-ref HEAD refs/heads/bar
 '
 
 test_expect_success 'symbolic-ref writes reflog entry' '
-- 
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