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. Furthermore, two tests are converted to not delete HEAD
anymore, as this results in a broken repository. They've instead been
updated to create a non-mandatory symbolic reference and delete that
one instead.

Some tests remain which exercise behaviour with broken references, which
cannot currently be converted to use regular git tooling.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t1400-update-ref.sh

@@ -48,17 +48,17 @@ test_expect_success "fail to delete $m with stale ref" '
 	test $B = "$(git show-ref -s --verify $m)"
 '
 test_expect_success "delete $m" '
-	test_when_finished "rm -f .git/$m" &&
+	test_when_finished "git update-ref -d $m" &&
 	git update-ref -d $m $B &&
-	test_path_is_missing .git/$m
+	test_must_fail git show-ref --verify -q $m
 '
 
 test_expect_success "delete $m without oldvalue verification" '
-	test_when_finished "rm -f .git/$m" &&
+	test_when_finished "git update-ref -d $m" &&
 	git update-ref $m $A &&
 	test $A = $(git show-ref -s --verify $m) &&
 	git update-ref -d $m &&
-	test_path_is_missing .git/$m
+	test_must_fail git show-ref --verify -q $m
 '
 
 test_expect_success "fail to create $n" '
@@ -80,26 +80,26 @@ test_expect_success "fail to delete $m (by HEAD) with stale ref" '
 	test $B = $(git show-ref -s --verify $m)
 '
 test_expect_success "delete $m (by HEAD)" '
-	test_when_finished "rm -f .git/$m" &&
+	test_when_finished "git update-ref -d $m" &&
 	git update-ref -d HEAD $B &&
-	test_path_is_missing .git/$m
+	test_must_fail git show-ref --verify -q $m
 '
 
 test_expect_success "deleting current branch adds message to HEAD's log" '
-	test_when_finished "rm -f .git/$m" &&
+	test_when_finished "git update-ref -d $m" &&
 	git update-ref $m $A &&
 	git symbolic-ref HEAD $m &&
 	git update-ref -m delete-$m -d $m &&
-	test_path_is_missing .git/$m &&
+	test_must_fail git show-ref --verify -q $m &&
 	grep "delete-$m$" .git/logs/HEAD
 '
 
 test_expect_success "deleting by HEAD adds message to HEAD's log" '
-	test_when_finished "rm -f .git/$m" &&
+	test_when_finished "git update-ref -d $m" &&
 	git update-ref $m $A &&
 	git symbolic-ref HEAD $m &&
 	git update-ref -m delete-by-head -d HEAD &&
-	test_path_is_missing .git/$m &&
+	test_must_fail git show-ref --verify -q $m &&
 	grep "delete-by-head$" .git/logs/HEAD
 '
 
@@ -188,31 +188,37 @@ 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 "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
 '
 
-cp -f .git/HEAD .git/HEAD.orig
 test_expect_success 'delete symref without dereference' '
-	test_when_finished "cp -f .git/HEAD.orig .git/HEAD" &&
-	git update-ref --no-deref -d HEAD &&
-	test_path_is_missing .git/HEAD
+	test_when_finished "git update-ref -d $m" &&
+	echo foo >foo.c &&
+	git add foo.c &&
+	git commit -m foo &&
+	git symbolic-ref SYMREF $m &&
+	git update-ref --no-deref -d SYMREF &&
+	git show-ref --verify -q $m &&
+	test_must_fail git show-ref --verify -q SYMREF &&
+	test_must_fail git symbolic-ref SYMREF
 '
 
 test_expect_success 'delete symref without dereference when the referred ref is packed' '
-	test_when_finished "cp -f .git/HEAD.orig .git/HEAD" &&
+	test_when_finished "git update-ref -d $m" &&
 	echo foo >foo.c &&
 	git add foo.c &&
 	git commit -m foo &&
+	git symbolic-ref SYMREF $m &&
 	git pack-refs --all &&
-	git update-ref --no-deref -d HEAD &&
-	test_path_is_missing .git/HEAD
+	git update-ref --no-deref -d SYMREF &&
+	git show-ref --verify -q $m &&
+	test_must_fail git show-ref --verify -q SYMREF &&
+	test_must_fail git symbolic-ref SYMREF
 '
 
-git update-ref -d $m
-
 test_expect_success 'update-ref -d is not confused by self-reference' '
 	git symbolic-ref refs/heads/self refs/heads/self &&
 	test_when_finished "rm -f .git/refs/heads/self" &&
@@ -226,25 +232,25 @@ test_expect_success 'update-ref --no-deref -d can delete self-reference' '
 	test_when_finished "rm -f .git/refs/heads/self" &&
 	test_path_is_file .git/refs/heads/self &&
 	git update-ref --no-deref -d refs/heads/self &&
-	test_path_is_missing .git/refs/heads/self
+	test_must_fail git show-ref --verify -q refs/heads/self
 '
 
 test_expect_success 'update-ref --no-deref -d can delete reference to bad ref' '
 	>.git/refs/heads/bad &&
 	test_when_finished "rm -f .git/refs/heads/bad" &&
 	git symbolic-ref refs/heads/ref-to-bad refs/heads/bad &&
-	test_when_finished "rm -f .git/refs/heads/ref-to-bad" &&
+	test_when_finished "git update-ref -d refs/heads/ref-to-bad" &&
 	test_path_is_file .git/refs/heads/ref-to-bad &&
 	git update-ref --no-deref -d refs/heads/ref-to-bad &&
-	test_path_is_missing .git/refs/heads/ref-to-bad
+	test_must_fail git show-ref --verify -q refs/heads/ref-to-bad
 '
 
 test_expect_success '(not) create HEAD with old sha1' '
 	test_must_fail git update-ref HEAD $A $B
 '
 test_expect_success "(not) prior created .git/$m" '
-	test_when_finished "rm -f .git/$m" &&
-	test_path_is_missing .git/$m
+	test_when_finished "git update-ref -d $m" &&
+	test_must_fail git show-ref --verify -q $m
 '
 
 test_expect_success 'create HEAD' '
@@ -254,7 +260,7 @@ test_expect_success '(not) change HEAD with wrong SHA1' '
 	test_must_fail git update-ref HEAD $B $Z
 '
 test_expect_success "(not) changed .git/$m" '
-	test_when_finished "rm -f .git/$m" &&
+	test_when_finished "git update-ref -d $m" &&
 	! test $B = $(git show-ref -s --verify $m)
 '
 
@@ -284,8 +290,8 @@ test_expect_success 'empty directory removal' '
 	test_path_is_file .git/refs/heads/d1/d2/r1 &&
 	test_path_is_file .git/logs/refs/heads/d1/d2/r1 &&
 	git branch -d d1/d2/r1 &&
-	test_path_is_missing .git/refs/heads/d1/d2 &&
-	test_path_is_missing .git/logs/refs/heads/d1/d2 &&
+	test_must_fail git show-ref --verify -q refs/heads/d1/d2 &&
+	test_must_fail git show-ref --verify -q logs/refs/heads/d1/d2 &&
 	test_path_is_file .git/refs/heads/d1/r2 &&
 	test_path_is_file .git/logs/refs/heads/d1/r2
 '
@@ -298,8 +304,8 @@ test_expect_success 'symref empty directory removal' '
 	test_path_is_file .git/refs/heads/e1/e2/r1 &&
 	test_path_is_file .git/logs/refs/heads/e1/e2/r1 &&
 	git update-ref -d HEAD &&
-	test_path_is_missing .git/refs/heads/e1/e2 &&
-	test_path_is_missing .git/logs/refs/heads/e1/e2 &&
+	test_must_fail git show-ref --verify -q refs/heads/e1/e2 &&
+	test_must_fail git show-ref --verify -q logs/refs/heads/e1/e2 &&
 	test_path_is_file .git/refs/heads/e1/r2 &&
 	test_path_is_file .git/logs/refs/heads/e1/r2 &&
 	test_path_is_file .git/logs/HEAD
@@ -1388,7 +1394,8 @@ test_expect_success 'handle per-worktree refs in refs/bisect' '
 		git rev-parse refs/bisect/something >../worktree-head &&
 		git for-each-ref | grep refs/bisect/something
 	) &&
-	test_path_is_missing .git/refs/bisect &&
+	git show-ref >actual &&
+	! grep 'refs/bisect' actual &&
 	test_must_fail git rev-parse refs/bisect/something &&
 	git update-ref refs/bisect/something HEAD &&
 	git rev-parse refs/bisect/something >main-head &&
@@ -1500,7 +1507,7 @@ test_expect_success 'transaction can handle abort' '
 	git update-ref --stdin <stdin >actual &&
 	printf "%s: ok\n" start abort >expect &&
 	test_cmp expect actual &&
-	test_path_is_missing .git/$b
+	test_must_fail git show-ref --verify -q $b
 '
 
 test_expect_success 'transaction aborts by default' '
@@ -1511,7 +1518,7 @@ test_expect_success 'transaction aborts by default' '
 	git update-ref --stdin <stdin >actual &&
 	printf "%s: ok\n" start >expect &&
 	test_cmp expect actual &&
-	test_path_is_missing .git/$b
+	test_must_fail git show-ref --verify -q $b
 '
 
 test_expect_success 'transaction with prepare aborts by default' '
@@ -1523,7 +1530,7 @@ test_expect_success 'transaction with prepare aborts by default' '
 	git update-ref --stdin <stdin >actual &&
 	printf "%s: ok\n" start prepare >expect &&
 	test_cmp expect actual &&
-	test_path_is_missing .git/$b
+	test_must_fail git show-ref --verify -q $b
 '
 
 test_done