t: convert tests to not access symrefs via the filesystem

Some of our tests access symbolic references via the filesystem
directly. While this works with the current files reference backend, it
this will break once we have a second reference backend in our codebase.

Refactor these tests to instead use git-symbolic-ref(1) or our
`ref-store` test tool. The latter is required in some cases where safety
checks of git-symbolic-ref(1) would otherwise reject writing a symbolic
reference.

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

t/t1400-update-ref.sh

@@ -221,15 +221,15 @@ test_expect_success 'delete symref without dereference when the referred ref is
 test_expect_success 'update-ref -d is not confused by self-reference' '
 	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF refs/heads/self" &&
 	git symbolic-ref refs/heads/self refs/heads/self &&
-	test_path_is_file .git/refs/heads/self &&
+	git symbolic-ref --no-recurse refs/heads/self &&
 	test_must_fail git update-ref -d refs/heads/self &&
-	test_path_is_file .git/refs/heads/self
+	git symbolic-ref --no-recurse refs/heads/self
 '
 
 test_expect_success 'update-ref --no-deref -d can delete self-reference' '
 	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF refs/heads/self" &&
 	git symbolic-ref refs/heads/self refs/heads/self &&
-	test_path_is_file .git/refs/heads/self &&
+	git symbolic-ref --no-recurse refs/heads/self &&
 	git update-ref --no-deref -d refs/heads/self &&
 	test_must_fail git show-ref --verify -q refs/heads/self
 '
@@ -239,7 +239,7 @@ test_expect_success 'update-ref --no-deref -d can delete reference to bad ref' '
 	test_when_finished "rm -f .git/refs/heads/bad" &&
 	git symbolic-ref refs/heads/ref-to-bad refs/heads/bad &&
 	test_when_finished "git update-ref -d refs/heads/ref-to-bad" &&
-	test_path_is_file .git/refs/heads/ref-to-bad &&
+	git symbolic-ref --no-recurse refs/heads/ref-to-bad &&
 	git update-ref --no-deref -d refs/heads/ref-to-bad &&
 	test_must_fail git show-ref --verify -q refs/heads/ref-to-bad
 '

t/t1430-bad-ref-name.sh

@@ -164,9 +164,9 @@ test_expect_success 'rev-parse skips symref pointing to broken name' '
 test_expect_success 'for-each-ref emits warnings for broken names' '
 	test-tool ref-store main update-ref msg "refs/heads/broken...ref" $main_sha1 $ZERO_OID REF_SKIP_REFNAME_VERIFICATION &&
 	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...ref" &&
-	printf "ref: refs/heads/broken...ref\n" >.git/refs/heads/badname &&
+	test-tool ref-store main create-symref refs/heads/badname refs/heads/broken...ref &&
 	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/badname" &&
-	printf "ref: refs/heads/main\n" >.git/refs/heads/broken...symref &&
+	test-tool ref-store main create-symref refs/heads/broken...symref refs/heads/main &&
 	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...symref" &&
 	git for-each-ref >output 2>error &&
 	! grep -e "broken\.\.\.ref" output &&
@@ -257,7 +257,7 @@ test_expect_success 'update-ref -d can delete broken name through symref' '
 '
 
 test_expect_success 'update-ref --no-deref -d can delete symref with broken name' '
-	printf "ref: refs/heads/main\n" >.git/refs/heads/broken...symref &&
+	test-tool ref-store main create-symref refs/heads/broken...symref refs/heads/main &&
 	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...symref" &&
 	test_ref_exists refs/heads/broken...symref &&
 	git update-ref --no-deref -d refs/heads/broken...symref >output 2>error &&
@@ -267,7 +267,7 @@ test_expect_success 'update-ref --no-deref -d can delete symref with broken name
 '
 
 test_expect_success 'branch -d can delete symref with broken name' '
-	printf "ref: refs/heads/main\n" >.git/refs/heads/broken...symref &&
+	test-tool ref-store main create-symref refs/heads/broken...symref refs/heads/main &&
 	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...symref" &&
 	test_ref_exists refs/heads/broken...symref &&
 	git branch -d broken...symref >output 2>error &&
@@ -277,7 +277,7 @@ test_expect_success 'branch -d can delete symref with broken name' '
 '
 
 test_expect_success 'update-ref --no-deref -d can delete dangling symref with broken name' '
-	printf "ref: refs/heads/idonotexist\n" >.git/refs/heads/broken...symref &&
+	test-tool ref-store main create-symref refs/heads/broken...symref refs/heads/idonotexist &&
 	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...symref" &&
 	test_ref_exists refs/heads/broken...symref &&
 	git update-ref --no-deref -d refs/heads/broken...symref >output 2>error &&
@@ -287,7 +287,7 @@ test_expect_success 'update-ref --no-deref -d can delete dangling symref with br
 '
 
 test_expect_success 'branch -d can delete dangling symref with broken name' '
-	printf "ref: refs/heads/idonotexist\n" >.git/refs/heads/broken...symref &&
+	test-tool ref-store main create-symref refs/heads/broken...symref refs/heads/idonotexist &&
 	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...symref" &&
 	test_ref_exists refs/heads/broken...symref &&
 	git branch -d broken...symref >output 2>error &&

t/t1450-fsck.sh

@@ -133,7 +133,7 @@ test_expect_success 'HEAD link pointing at a funny object' '
 
 test_expect_success 'HEAD link pointing at a funny place' '
 	test_when_finished "git update-ref --no-deref HEAD $orig_head" &&
-	echo "ref: refs/funny/place" >.git/HEAD &&
+	test-tool ref-store main create-symref HEAD refs/funny/place &&
 	# avoid corrupt/broken HEAD from interfering with repo discovery
 	test_must_fail env GIT_DIR=.git git fsck 2>out &&
 	test_i18ngrep "HEAD points to something strange" out
@@ -169,7 +169,7 @@ test_expect_success 'other worktree HEAD link pointing at missing object' '
 test_expect_success 'other worktree HEAD link pointing at a funny place' '
 	test_when_finished "rm -rf .git/worktrees other" &&
 	git worktree add other &&
-	echo "ref: refs/funny/place" >.git/worktrees/other/HEAD &&
+	git -C other symbolic-ref HEAD refs/funny/place &&
 	test_must_fail git fsck 2>out &&
 	test_i18ngrep "worktrees/other/HEAD points to something strange" out
 '

t/t3200-branch.sh

@@ -215,10 +215,13 @@ test_expect_success 'git branch -M should leave orphaned HEAD alone' '
 		cd orphan &&
 		test_commit initial &&
 		git checkout --orphan lonely &&
-		grep lonely .git/HEAD &&
+		git symbolic-ref HEAD >expect &&
+		echo refs/heads/lonely >actual &&
+		test_cmp expect actual &&
 		test_ref_missing refs/head/lonely &&
 		git branch -M main mistress &&
-		grep lonely .git/HEAD
+		git symbolic-ref HEAD >expect &&
+		test_cmp expect actual
 	)
 '
 
@@ -809,7 +812,7 @@ test_expect_success 'deleting a symref' '
 
 test_expect_success 'deleting a dangling symref' '
 	git symbolic-ref refs/heads/dangling-symref nowhere &&
-	test_path_is_file .git/refs/heads/dangling-symref &&
+	git symbolic-ref --no-recurse refs/heads/dangling-symref &&
 	echo "Deleted branch dangling-symref (was nowhere)." >expect &&
 	git branch -d dangling-symref >actual &&
 	test_ref_missing refs/heads/dangling-symref &&

t/t4013-diff-various.sh

@@ -522,7 +522,7 @@ test_expect_success 'log -S requires an argument' '
 '
 
 test_expect_success 'diff --cached on unborn branch' '
-	echo ref: refs/heads/unborn >.git/HEAD &&
+	git symbolic-ref HEAD refs/heads/unborn &&
 	git diff --cached >result &&
 	process_diffs result >actual &&
 	process_diffs "$TEST_DIRECTORY/t4013/diff.diff_--cached" >expected &&

t/t4202-log.sh

@@ -2265,7 +2265,7 @@ test_expect_success REFFILES 'log diagnoses bogus HEAD hash' '
 
 test_expect_success REFFILES 'log diagnoses bogus HEAD symref' '
 	git init empty &&
-	echo "ref: refs/heads/invalid.lock" > empty/.git/HEAD &&
+	test-tool -C empty ref-store main create-symref HEAD refs/heads/invalid.lock &&
 	test_must_fail git -C empty log 2>stderr &&
 	test_i18ngrep broken stderr &&
 	test_must_fail git -C empty log --default totally-bogus 2>stderr &&

t/t5605-clone-local.sh

@@ -65,7 +65,7 @@ test_expect_success 'Even without -l, local will make a hardlink' '
 '
 
 test_expect_success 'local clone of repo with nonexistent ref in HEAD' '
-	echo "ref: refs/heads/nonexistent" > a.git/HEAD &&
+	git -C a.git symbolic-ref HEAD refs/heads/nonexistent &&
 	git clone a d &&
 	(cd d &&
 	git fetch &&

t/t5702-protocol-v2.sh

@@ -221,7 +221,9 @@ test_expect_success 'clone of empty repo propagates name of default branch' '
 	GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME= \
 	git -c init.defaultBranch=main -c protocol.version=2 \
 		clone "file://$(pwd)/file_empty_parent" file_empty_child &&
-	grep "refs/heads/mydefaultbranch" file_empty_child/.git/HEAD
+	echo refs/heads/mydefaultbranch >expect &&
+	git -C file_empty_child symbolic-ref HEAD >actual &&
+	test_cmp expect actual
 '
 
 test_expect_success '...but not if explicitly forbidden by config' '
@@ -234,7 +236,9 @@ test_expect_success '...but not if explicitly forbidden by config' '
 	GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME= \
 	git -c init.defaultBranch=main -c protocol.version=2 \
 		clone "file://$(pwd)/file_empty_parent" file_empty_child &&
-	! grep "refs/heads/mydefaultbranch" file_empty_child/.git/HEAD
+	echo refs/heads/main >expect &&
+	git -C file_empty_child symbolic-ref HEAD >actual &&
+	test_cmp expect actual
 '
 
 test_expect_success 'bare clone propagates empty default branch' '
@@ -247,7 +251,9 @@ test_expect_success 'bare clone propagates empty default branch' '
 	git -c init.defaultBranch=main -c protocol.version=2 \
 		clone --bare \
 		"file://$(pwd)/file_empty_parent" file_empty_child.git &&
-	grep "refs/heads/mydefaultbranch" file_empty_child.git/HEAD
+	echo "refs/heads/mydefaultbranch" >expect &&
+	git -C file_empty_child.git symbolic-ref HEAD >actual &&
+	test_cmp expect actual
 '
 
 test_expect_success 'clone propagates unborn HEAD from non-empty repo' '
@@ -265,7 +271,9 @@ test_expect_success 'clone propagates unborn HEAD from non-empty repo' '
 	git -c init.defaultBranch=main -c protocol.version=2 \
 		clone "file://$(pwd)/file_unborn_parent" \
 		file_unborn_child 2>stderr &&
-	grep "refs/heads/mydefaultbranch" file_unborn_child/.git/HEAD &&
+	echo "refs/heads/mydefaultbranch" >expect &&
+	git -C file_unborn_child symbolic-ref HEAD >actual &&
+	test_cmp expect actual &&
 	grep "warning: remote HEAD refers to nonexistent ref" stderr
 '
 
@@ -295,7 +303,9 @@ test_expect_success 'bare clone propagates unborn HEAD from non-empty repo' '
 	git -c init.defaultBranch=main -c protocol.version=2 \
 		clone --bare "file://$(pwd)/file_unborn_parent" \
 		file_unborn_child.git 2>stderr &&
-	grep "refs/heads/mydefaultbranch" file_unborn_child.git/HEAD &&
+	echo "refs/heads/mydefaultbranch" >expect &&
+	git -C file_unborn_child.git symbolic-ref HEAD >actual &&
+	test_cmp expect actual &&
 	! grep "warning:" stderr
 '
 
@@ -315,7 +325,9 @@ test_expect_success 'defaulted HEAD uses remote branch if available' '
 	git -c init.defaultBranch=branchwithstuff -c protocol.version=2 \
 		clone "file://$(pwd)/file_unborn_parent" \
 		file_unborn_child 2>stderr &&
-	grep "refs/heads/branchwithstuff" file_unborn_child/.git/HEAD &&
+	echo "refs/heads/branchwithstuff" >expect &&
+	git -C file_unborn_child symbolic-ref HEAD >actual &&
+	test_cmp expect actual &&
 	test_path_is_file file_unborn_child/stuff.t &&
 	! grep "warning:" stderr
 '

t/t9133-git-svn-nested-git-repo.sh

@@ -11,7 +11,7 @@ test_expect_success 'setup repo with a git repo inside it' '
 	(
 		cd s &&
 		git init &&
-		test -f .git/HEAD &&
+		git symbolic-ref HEAD &&
 		> .git/a &&
 		echo a > a &&
 		svn_cmd add .git a &&