diff --git a/t/t0600-reffiles-backend.sh b/t/t0600-reffiles-backend.sh
new file mode 100755
index 00000000000..2f910bd76ad
--- /dev/null
+++ b/t/t0600-reffiles-backend.sh
@@ -0,0 +1,263 @@
+#!/bin/sh
+
+test_description='Test reffiles backend'
+
+GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
+export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
+
+TEST_PASSES_SANITIZE_LEAK=true
+. ./test-lib.sh
+
+if ! test_have_prereq REFFILES
+	then
+		skip_all='skipping reffiles specific tests'
+		test_done
+fi
+
+test_expect_success 'setup' '
+	git commit --allow-empty -m Initial &&
+	C=$(git rev-parse HEAD) &&
+	git commit --allow-empty -m Second &&
+	D=$(git rev-parse HEAD) &&
+	git commit --allow-empty -m Third &&
+	E=$(git rev-parse HEAD)
+'
+
+test_expect_success 'empty directory should not fool rev-parse' '
+	prefix=refs/e-rev-parse &&
+	git update-ref $prefix/foo $C &&
+	git pack-refs --all &&
+	mkdir -p .git/$prefix/foo/bar/baz &&
+	echo "$C" >expected &&
+	git rev-parse $prefix/foo >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'empty directory should not fool for-each-ref' '
+	prefix=refs/e-for-each-ref &&
+	git update-ref $prefix/foo $C &&
+	git for-each-ref $prefix >expected &&
+	git pack-refs --all &&
+	mkdir -p .git/$prefix/foo/bar/baz &&
+	git for-each-ref $prefix >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'empty directory should not fool create' '
+	prefix=refs/e-create &&
+	mkdir -p .git/$prefix/foo/bar/baz &&
+	printf "create %s $C\n" $prefix/foo |
+	git update-ref --stdin
+'
+
+test_expect_success 'empty directory should not fool verify' '
+	prefix=refs/e-verify &&
+	git update-ref $prefix/foo $C &&
+	git pack-refs --all &&
+	mkdir -p .git/$prefix/foo/bar/baz &&
+	printf "verify %s $C\n" $prefix/foo |
+	git update-ref --stdin
+'
+
+test_expect_success 'empty directory should not fool 1-arg update' '
+	prefix=refs/e-update-1 &&
+	git update-ref $prefix/foo $C &&
+	git pack-refs --all &&
+	mkdir -p .git/$prefix/foo/bar/baz &&
+	printf "update %s $D\n" $prefix/foo |
+	git update-ref --stdin
+'
+
+test_expect_success 'empty directory should not fool 2-arg update' '
+	prefix=refs/e-update-2 &&
+	git update-ref $prefix/foo $C &&
+	git pack-refs --all &&
+	mkdir -p .git/$prefix/foo/bar/baz &&
+	printf "update %s $D $C\n" $prefix/foo |
+	git update-ref --stdin
+'
+
+test_expect_success 'empty directory should not fool 0-arg delete' '
+	prefix=refs/e-delete-0 &&
+	git update-ref $prefix/foo $C &&
+	git pack-refs --all &&
+	mkdir -p .git/$prefix/foo/bar/baz &&
+	printf "delete %s\n" $prefix/foo |
+	git update-ref --stdin
+'
+
+test_expect_success 'empty directory should not fool 1-arg delete' '
+	prefix=refs/e-delete-1 &&
+	git update-ref $prefix/foo $C &&
+	git pack-refs --all &&
+	mkdir -p .git/$prefix/foo/bar/baz &&
+	printf "delete %s $C\n" $prefix/foo |
+	git update-ref --stdin
+'
+
+test_expect_success 'non-empty directory blocks create' '
+	prefix=refs/ne-create &&
+	mkdir -p .git/$prefix/foo/bar &&
+	: >.git/$prefix/foo/bar/baz.lock &&
+	test_when_finished "rm -f .git/$prefix/foo/bar/baz.lock" &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $SQ$prefix/foo$SQ: there is a non-empty directory $SQ.git/$prefix/foo$SQ blocking reference $SQ$prefix/foo$SQ
+	EOF
+	printf "%s\n" "update $prefix/foo $C" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $SQ$prefix/foo$SQ: unable to resolve reference $SQ$prefix/foo$SQ
+	EOF
+	printf "%s\n" "update $prefix/foo $D $C" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err
+'
+
+test_expect_success 'broken reference blocks create' '
+	prefix=refs/broken-create &&
+	mkdir -p .git/$prefix &&
+	echo "gobbledigook" >.git/$prefix/foo &&
+	test_when_finished "rm -f .git/$prefix/foo" &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $SQ$prefix/foo$SQ: unable to resolve reference $SQ$prefix/foo$SQ: reference broken
+	EOF
+	printf "%s\n" "update $prefix/foo $C" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $SQ$prefix/foo$SQ: unable to resolve reference $SQ$prefix/foo$SQ: reference broken
+	EOF
+	printf "%s\n" "update $prefix/foo $D $C" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err
+'
+
+test_expect_success 'non-empty directory blocks indirect create' '
+	prefix=refs/ne-indirect-create &&
+	git symbolic-ref $prefix/symref $prefix/foo &&
+	mkdir -p .git/$prefix/foo/bar &&
+	: >.git/$prefix/foo/bar/baz.lock &&
+	test_when_finished "rm -f .git/$prefix/foo/bar/baz.lock" &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $SQ$prefix/symref$SQ: there is a non-empty directory $SQ.git/$prefix/foo$SQ blocking reference $SQ$prefix/foo$SQ
+	EOF
+	printf "%s\n" "update $prefix/symref $C" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $SQ$prefix/symref$SQ: unable to resolve reference $SQ$prefix/foo$SQ
+	EOF
+	printf "%s\n" "update $prefix/symref $D $C" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err
+'
+
+test_expect_success 'broken reference blocks indirect create' '
+	prefix=refs/broken-indirect-create &&
+	git symbolic-ref $prefix/symref $prefix/foo &&
+	echo "gobbledigook" >.git/$prefix/foo &&
+	test_when_finished "rm -f .git/$prefix/foo" &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $SQ$prefix/symref$SQ: unable to resolve reference $SQ$prefix/foo$SQ: reference broken
+	EOF
+	printf "%s\n" "update $prefix/symref $C" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $SQ$prefix/symref$SQ: unable to resolve reference $SQ$prefix/foo$SQ: reference broken
+	EOF
+	printf "%s\n" "update $prefix/symref $D $C" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err
+'
+
+test_expect_success 'no bogus intermediate values during delete' '
+	prefix=refs/slow-transaction &&
+	# Set up a reference with differing loose and packed versions:
+	git update-ref $prefix/foo $C &&
+	git pack-refs --all &&
+	git update-ref $prefix/foo $D &&
+	# Now try to update the reference, but hold the `packed-refs` lock
+	# for a while to see what happens while the process is blocked:
+	: >.git/packed-refs.lock &&
+	test_when_finished "rm -f .git/packed-refs.lock" &&
+	{
+		# Note: the following command is intentionally run in the
+		# background. We increase the timeout so that `update-ref`
+		# attempts to acquire the `packed-refs` lock for much longer
+		# than it takes for us to do the check then delete it:
+		git -c core.packedrefstimeout=30000 update-ref -d $prefix/foo &
+	} &&
+	pid2=$! &&
+	# Give update-ref plenty of time to get to the point where it tries
+	# to lock packed-refs:
+	sleep 1 &&
+	# Make sure that update-ref did not complete despite the lock:
+	kill -0 $pid2 &&
+	# Verify that the reference still has its old value:
+	sha1=$(git rev-parse --verify --quiet $prefix/foo || echo undefined) &&
+	case "$sha1" in
+	$D)
+		# This is what we hope for; it means that nothing
+		# user-visible has changed yet.
+		: ;;
+	undefined)
+		# This is not correct; it means the deletion has happened
+		# already even though update-ref should not have been
+		# able to acquire the lock yet.
+		echo "$prefix/foo deleted prematurely" &&
+		break
+		;;
+	$C)
+		# This value should never be seen. Probably the loose
+		# reference has been deleted but the packed reference
+		# is still there:
+		echo "$prefix/foo incorrectly observed to be C" &&
+		break
+		;;
+	*)
+		# WTF?
+		echo "unexpected value observed for $prefix/foo: $sha1" &&
+		break
+		;;
+	esac >out &&
+	rm -f .git/packed-refs.lock &&
+	wait $pid2 &&
+	test_must_be_empty out &&
+	test_must_fail git rev-parse --verify --quiet $prefix/foo
+'
+
+test_expect_success 'delete fails cleanly if packed-refs file is locked' '
+	prefix=refs/locked-packed-refs &&
+	# Set up a reference with differing loose and packed versions:
+	git update-ref $prefix/foo $C &&
+	git pack-refs --all &&
+	git update-ref $prefix/foo $D &&
+	git for-each-ref $prefix >unchanged &&
+	# Now try to delete it while the `packed-refs` lock is held:
+	: >.git/packed-refs.lock &&
+	test_when_finished "rm -f .git/packed-refs.lock" &&
+	test_must_fail git update-ref -d $prefix/foo >out 2>err &&
+	git for-each-ref $prefix >actual &&
+	test_grep "Unable to create $SQ.*packed-refs.lock$SQ: " err &&
+	test_cmp unchanged actual
+'
+
+test_expect_success 'delete fails cleanly if packed-refs.new write fails' '
+	# Setup and expectations are similar to the test above.
+	prefix=refs/failed-packed-refs &&
+	git update-ref $prefix/foo $C &&
+	git pack-refs --all &&
+	git update-ref $prefix/foo $D &&
+	git for-each-ref $prefix >unchanged &&
+	# This should not happen in practice, but it is an easy way to get a
+	# reliable error (we open with create_tempfile(), which uses O_EXCL).
+	: >.git/packed-refs.new &&
+	test_when_finished "rm -f .git/packed-refs.new" &&
+	test_must_fail git update-ref -d $prefix/foo &&
+	git for-each-ref $prefix >actual &&
+	test_cmp unchanged actual
+'
+
+test_done
diff --git a/t/t1404-update-ref-errors.sh b/t/t1404-update-ref-errors.sh
index 0369beea33b..00b70137053 100755
--- a/t/t1404-update-ref-errors.sh
+++ b/t/t1404-update-ref-errors.sh
@@ -191,78 +191,6 @@ test_expect_success 'one new ref is a simple prefix of another' '
 
 '
 
-test_expect_success REFFILES 'empty directory should not fool rev-parse' '
-	prefix=refs/e-rev-parse &&
-	git update-ref $prefix/foo $C &&
-	git pack-refs --all &&
-	mkdir -p .git/$prefix/foo/bar/baz &&
-	echo "$C" >expected &&
-	git rev-parse $prefix/foo >actual &&
-	test_cmp expected actual
-'
-
-test_expect_success REFFILES 'empty directory should not fool for-each-ref' '
-	prefix=refs/e-for-each-ref &&
-	git update-ref $prefix/foo $C &&
-	git for-each-ref $prefix >expected &&
-	git pack-refs --all &&
-	mkdir -p .git/$prefix/foo/bar/baz &&
-	git for-each-ref $prefix >actual &&
-	test_cmp expected actual
-'
-
-test_expect_success REFFILES 'empty directory should not fool create' '
-	prefix=refs/e-create &&
-	mkdir -p .git/$prefix/foo/bar/baz &&
-	printf "create %s $C\n" $prefix/foo |
-	git update-ref --stdin
-'
-
-test_expect_success REFFILES 'empty directory should not fool verify' '
-	prefix=refs/e-verify &&
-	git update-ref $prefix/foo $C &&
-	git pack-refs --all &&
-	mkdir -p .git/$prefix/foo/bar/baz &&
-	printf "verify %s $C\n" $prefix/foo |
-	git update-ref --stdin
-'
-
-test_expect_success REFFILES 'empty directory should not fool 1-arg update' '
-	prefix=refs/e-update-1 &&
-	git update-ref $prefix/foo $C &&
-	git pack-refs --all &&
-	mkdir -p .git/$prefix/foo/bar/baz &&
-	printf "update %s $D\n" $prefix/foo |
-	git update-ref --stdin
-'
-
-test_expect_success REFFILES 'empty directory should not fool 2-arg update' '
-	prefix=refs/e-update-2 &&
-	git update-ref $prefix/foo $C &&
-	git pack-refs --all &&
-	mkdir -p .git/$prefix/foo/bar/baz &&
-	printf "update %s $D $C\n" $prefix/foo |
-	git update-ref --stdin
-'
-
-test_expect_success REFFILES 'empty directory should not fool 0-arg delete' '
-	prefix=refs/e-delete-0 &&
-	git update-ref $prefix/foo $C &&
-	git pack-refs --all &&
-	mkdir -p .git/$prefix/foo/bar/baz &&
-	printf "delete %s\n" $prefix/foo |
-	git update-ref --stdin
-'
-
-test_expect_success REFFILES 'empty directory should not fool 1-arg delete' '
-	prefix=refs/e-delete-1 &&
-	git update-ref $prefix/foo $C &&
-	git pack-refs --all &&
-	mkdir -p .git/$prefix/foo/bar/baz &&
-	printf "delete %s $C\n" $prefix/foo |
-	git update-ref --stdin
-'
-
 test_expect_success REFFILES 'D/F conflict prevents add long + delete short' '
 	df_test refs/df-al-ds --add-del foo/bar foo
 '
@@ -468,169 +396,4 @@ test_expect_success 'incorrect old value blocks indirect no-deref delete' '
 	test_cmp expected output.err
 '
 
-test_expect_success REFFILES 'non-empty directory blocks create' '
-	prefix=refs/ne-create &&
-	mkdir -p .git/$prefix/foo/bar &&
-	: >.git/$prefix/foo/bar/baz.lock &&
-	test_when_finished "rm -f .git/$prefix/foo/bar/baz.lock" &&
-	cat >expected <<-EOF &&
-	fatal: cannot lock ref $SQ$prefix/foo$SQ: there is a non-empty directory $SQ.git/$prefix/foo$SQ blocking reference $SQ$prefix/foo$SQ
-	EOF
-	printf "%s\n" "update $prefix/foo $C" |
-	test_must_fail git update-ref --stdin 2>output.err &&
-	test_cmp expected output.err &&
-	cat >expected <<-EOF &&
-	fatal: cannot lock ref $SQ$prefix/foo$SQ: unable to resolve reference $SQ$prefix/foo$SQ
-	EOF
-	printf "%s\n" "update $prefix/foo $D $C" |
-	test_must_fail git update-ref --stdin 2>output.err &&
-	test_cmp expected output.err
-'
-
-test_expect_success REFFILES 'broken reference blocks create' '
-	prefix=refs/broken-create &&
-	mkdir -p .git/$prefix &&
-	echo "gobbledigook" >.git/$prefix/foo &&
-	test_when_finished "rm -f .git/$prefix/foo" &&
-	cat >expected <<-EOF &&
-	fatal: cannot lock ref $SQ$prefix/foo$SQ: unable to resolve reference $SQ$prefix/foo$SQ: reference broken
-	EOF
-	printf "%s\n" "update $prefix/foo $C" |
-	test_must_fail git update-ref --stdin 2>output.err &&
-	test_cmp expected output.err &&
-	cat >expected <<-EOF &&
-	fatal: cannot lock ref $SQ$prefix/foo$SQ: unable to resolve reference $SQ$prefix/foo$SQ: reference broken
-	EOF
-	printf "%s\n" "update $prefix/foo $D $C" |
-	test_must_fail git update-ref --stdin 2>output.err &&
-	test_cmp expected output.err
-'
-
-test_expect_success REFFILES 'non-empty directory blocks indirect create' '
-	prefix=refs/ne-indirect-create &&
-	git symbolic-ref $prefix/symref $prefix/foo &&
-	mkdir -p .git/$prefix/foo/bar &&
-	: >.git/$prefix/foo/bar/baz.lock &&
-	test_when_finished "rm -f .git/$prefix/foo/bar/baz.lock" &&
-	cat >expected <<-EOF &&
-	fatal: cannot lock ref $SQ$prefix/symref$SQ: there is a non-empty directory $SQ.git/$prefix/foo$SQ blocking reference $SQ$prefix/foo$SQ
-	EOF
-	printf "%s\n" "update $prefix/symref $C" |
-	test_must_fail git update-ref --stdin 2>output.err &&
-	test_cmp expected output.err &&
-	cat >expected <<-EOF &&
-	fatal: cannot lock ref $SQ$prefix/symref$SQ: unable to resolve reference $SQ$prefix/foo$SQ
-	EOF
-	printf "%s\n" "update $prefix/symref $D $C" |
-	test_must_fail git update-ref --stdin 2>output.err &&
-	test_cmp expected output.err
-'
-
-test_expect_success REFFILES 'broken reference blocks indirect create' '
-	prefix=refs/broken-indirect-create &&
-	git symbolic-ref $prefix/symref $prefix/foo &&
-	echo "gobbledigook" >.git/$prefix/foo &&
-	test_when_finished "rm -f .git/$prefix/foo" &&
-	cat >expected <<-EOF &&
-	fatal: cannot lock ref $SQ$prefix/symref$SQ: unable to resolve reference $SQ$prefix/foo$SQ: reference broken
-	EOF
-	printf "%s\n" "update $prefix/symref $C" |
-	test_must_fail git update-ref --stdin 2>output.err &&
-	test_cmp expected output.err &&
-	cat >expected <<-EOF &&
-	fatal: cannot lock ref $SQ$prefix/symref$SQ: unable to resolve reference $SQ$prefix/foo$SQ: reference broken
-	EOF
-	printf "%s\n" "update $prefix/symref $D $C" |
-	test_must_fail git update-ref --stdin 2>output.err &&
-	test_cmp expected output.err
-'
-
-test_expect_success REFFILES 'no bogus intermediate values during delete' '
-	prefix=refs/slow-transaction &&
-	# Set up a reference with differing loose and packed versions:
-	git update-ref $prefix/foo $C &&
-	git pack-refs --all &&
-	git update-ref $prefix/foo $D &&
-	# Now try to update the reference, but hold the `packed-refs` lock
-	# for a while to see what happens while the process is blocked:
-	: >.git/packed-refs.lock &&
-	test_when_finished "rm -f .git/packed-refs.lock" &&
-	{
-		# Note: the following command is intentionally run in the
-		# background. We increase the timeout so that `update-ref`
-		# attempts to acquire the `packed-refs` lock for much longer
-		# than it takes for us to do the check then delete it:
-		git -c core.packedrefstimeout=30000 update-ref -d $prefix/foo &
-	} &&
-	pid2=$! &&
-	# Give update-ref plenty of time to get to the point where it tries
-	# to lock packed-refs:
-	sleep 1 &&
-	# Make sure that update-ref did not complete despite the lock:
-	kill -0 $pid2 &&
-	# Verify that the reference still has its old value:
-	sha1=$(git rev-parse --verify --quiet $prefix/foo || echo undefined) &&
-	case "$sha1" in
-	$D)
-		# This is what we hope for; it means that nothing
-		# user-visible has changed yet.
-		: ;;
-	undefined)
-		# This is not correct; it means the deletion has happened
-		# already even though update-ref should not have been
-		# able to acquire the lock yet.
-		echo "$prefix/foo deleted prematurely" &&
-		break
-		;;
-	$C)
-		# This value should never be seen. Probably the loose
-		# reference has been deleted but the packed reference
-		# is still there:
-		echo "$prefix/foo incorrectly observed to be C" &&
-		break
-		;;
-	*)
-		# WTF?
-		echo "unexpected value observed for $prefix/foo: $sha1" &&
-		break
-		;;
-	esac >out &&
-	rm -f .git/packed-refs.lock &&
-	wait $pid2 &&
-	test_must_be_empty out &&
-	test_must_fail git rev-parse --verify --quiet $prefix/foo
-'
-
-test_expect_success REFFILES 'delete fails cleanly if packed-refs file is locked' '
-	prefix=refs/locked-packed-refs &&
-	# Set up a reference with differing loose and packed versions:
-	git update-ref $prefix/foo $C &&
-	git pack-refs --all &&
-	git update-ref $prefix/foo $D &&
-	git for-each-ref $prefix >unchanged &&
-	# Now try to delete it while the `packed-refs` lock is held:
-	: >.git/packed-refs.lock &&
-	test_when_finished "rm -f .git/packed-refs.lock" &&
-	test_must_fail git update-ref -d $prefix/foo >out 2>err &&
-	git for-each-ref $prefix >actual &&
-	test_grep "Unable to create $SQ.*packed-refs.lock$SQ: " err &&
-	test_cmp unchanged actual
-'
-
-test_expect_success REFFILES 'delete fails cleanly if packed-refs.new write fails' '
-	# Setup and expectations are similar to the test above.
-	prefix=refs/failed-packed-refs &&
-	git update-ref $prefix/foo $C &&
-	git pack-refs --all &&
-	git update-ref $prefix/foo $D &&
-	git for-each-ref $prefix >unchanged &&
-	# This should not happen in practice, but it is an easy way to get a
-	# reliable error (we open with create_tempfile(), which uses O_EXCL).
-	: >.git/packed-refs.new &&
-	test_when_finished "rm -f .git/packed-refs.new" &&
-	test_must_fail git update-ref -d $prefix/foo &&
-	git for-each-ref $prefix >actual &&
-	test_cmp unchanged actual
-'
-
 test_done
