Merge branch 'ms/refs-exists'

"git refs exists" that works like "git show-ref --exists" has been
added.

* ms/refs-exists:
  t: add test for git refs exists subcommand
  t1422: refactor tests to be shareable
  t1403: split 'show-ref --exists' tests into a separate file
  builtin/refs: add 'exists' subcommand

7 files changed, 154 insertions, 66 deletions

diff --git a/Documentation/git-refs.adoc b/Documentation/git-refs.adoc
index d462953fb5..bfa9b3ea2d 100644
--- a/Documentation/git-refs.adoc
+++ b/Documentation/git-refs.adoc
@@ -18,6 +18,7 @@ git refs list [--count=<count>] [--shell|--perl|--python|--tcl]
 		   [--contains[=<object>]] [--no-contains[=<object>]]
 		   [(--exclude=<pattern>)...] [--start-after=<marker>]
 		   [ --stdin | (<pattern>...)]
+git refs exists <ref>
 
 DESCRIPTION
 -----------
@@ -38,6 +39,12 @@ list::
 	formatting, and sorting. This subcommand is an alias for
 	linkgit:git-for-each-ref[1] and offers identical functionality.
 
+exists::
+	Check whether the given reference exists. Returns an exit code of 0 if
+	it does, 2 if it is missing, and 1 in case looking up the reference
+	failed with an error other than the reference being missing. This does
+	not verify whether the reference resolves to an actual object.
+
 OPTIONS
 -------
 
diff --git a/builtin/refs.c b/builtin/refs.c
index 76224feba4..91548783b7 100644
--- a/builtin/refs.c
+++ b/builtin/refs.c
@@ -7,6 +7,7 @@
 #include "strbuf.h"
 #include "worktree.h"
 #include "for-each-ref.h"
+#include "refs/refs-internal.h"
 
 #define REFS_MIGRATE_USAGE \
 	N_("git refs migrate --ref-format=<format> [--no-reflog] [--dry-run]")
@@ -14,6 +15,9 @@
 #define REFS_VERIFY_USAGE \
 	N_("git refs verify [--strict] [--verbose]")
 
+#define REFS_EXISTS_USAGE \
+	N_("git refs exists <ref>")
+
 static int cmd_refs_migrate(int argc, const char **argv, const char *prefix,
 			    struct repository *repo UNUSED)
 {
@@ -113,6 +117,48 @@ static int cmd_refs_list(int argc, const char **argv, const char *prefix,
 	return for_each_ref_core(argc, argv, prefix, repo, refs_list_usage);
 }
 
+static int cmd_refs_exists(int argc, const char **argv, const char *prefix,
+			   struct repository *repo UNUSED)
+{
+	struct strbuf unused_referent = STRBUF_INIT;
+	struct object_id unused_oid;
+	unsigned int unused_type;
+	int failure_errno = 0;
+	const char *ref;
+	int ret = 0;
+	const char * const exists_usage[] = {
+		REFS_EXISTS_USAGE,
+		NULL,
+	};
+	struct option options[] = {
+		OPT_END(),
+	};
+
+	argc = parse_options(argc, argv, prefix, options, exists_usage, 0);
+	if (argc != 1)
+		die(_("'git refs exists' requires a reference"));
+
+	ref = *argv++;
+	if (refs_read_raw_ref(get_main_ref_store(the_repository), ref,
+			      &unused_oid, &unused_referent, &unused_type,
+			      &failure_errno)) {
+		if (failure_errno == ENOENT || failure_errno == EISDIR) {
+			error(_("reference does not exist"));
+			ret = 2;
+		} else {
+			errno = failure_errno;
+			error_errno(_("failed to look up reference"));
+			ret = 1;
+		}
+
+		goto out;
+	}
+
+out:
+	strbuf_release(&unused_referent);
+	return ret;
+}
+
 int cmd_refs(int argc,
 	     const char **argv,
 	     const char *prefix,
@@ -122,6 +168,7 @@ int cmd_refs(int argc,
 		REFS_MIGRATE_USAGE,
 		REFS_VERIFY_USAGE,
 		"git refs list " COMMON_USAGE_FOR_EACH_REF,
+		REFS_EXISTS_USAGE,
 		NULL,
 	};
 	parse_opt_subcommand_fn *fn = NULL;
@@ -129,6 +176,7 @@ int cmd_refs(int argc,
 		OPT_SUBCOMMAND("migrate", &fn, cmd_refs_migrate),
 		OPT_SUBCOMMAND("verify", &fn, cmd_refs_verify),
 		OPT_SUBCOMMAND("list", &fn, cmd_refs_list),
+		OPT_SUBCOMMAND("exists", &fn, cmd_refs_exists),
 		OPT_END(),
 	};
 
diff --git a/t/meson.build b/t/meson.build
index 82af229be3..7974795fe4 100644
--- a/t/meson.build
+++ b/t/meson.build
@@ -206,11 +206,13 @@ integration_tests = [
   't1419-exclude-refs.sh',
   't1420-lost-found.sh',
   't1421-reflog-write.sh',
+  't1422-show-ref-exists.sh',
   't1430-bad-ref-name.sh',
   't1450-fsck.sh',
   't1451-fsck-buffer.sh',
   't1460-refs-migrate.sh',
   't1461-refs-list.sh',
+  't1462-refs-exists.sh',
   't1500-rev-parse.sh',
   't1501-work-tree.sh',
   't1502-rev-parse-parseopt.sh',
@@ -1221,4 +1223,4 @@ if perl.found() and time.found()
       timeout: 0,
     )
   endforeach
-endif
\ No newline at end of file
+endif
diff --git a/t/show-ref-exists-tests.sh b/t/show-ref-exists-tests.sh
new file mode 100644
index 0000000000..36e8e9df33
--- /dev/null
+++ b/t/show-ref-exists-tests.sh
@@ -0,0 +1,77 @@
+git_show_ref_exists=${git_show_ref_exists:-git show-ref --exists}
+
+test_expect_success setup '
+	test_commit --annotate A &&
+	git checkout -b side &&
+	test_commit --annotate B &&
+	git checkout main &&
+	test_commit C &&
+	git branch B A^0
+'
+
+test_expect_success '--exists with existing reference' '
+	${git_show_ref_exists} refs/heads/$GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
+'
+
+test_expect_success '--exists with missing reference' '
+	test_expect_code 2 ${git_show_ref_exists} refs/heads/does-not-exist
+'
+
+test_expect_success '--exists does not use DWIM' '
+	test_expect_code 2 ${git_show_ref_exists} $GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME 2>err &&
+	grep "reference does not exist" err
+'
+
+test_expect_success '--exists with HEAD' '
+	${git_show_ref_exists} HEAD
+'
+
+test_expect_success '--exists with bad reference name' '
+	test_when_finished "git update-ref -d refs/heads/bad...name" &&
+	new_oid=$(git rev-parse HEAD) &&
+	test-tool ref-store main update-ref msg refs/heads/bad...name $new_oid $ZERO_OID REF_SKIP_REFNAME_VERIFICATION &&
+	${git_show_ref_exists} refs/heads/bad...name
+'
+
+test_expect_success '--exists with arbitrary symref' '
+	test_when_finished "git symbolic-ref -d refs/symref" &&
+	git symbolic-ref refs/symref refs/heads/$GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME &&
+	${git_show_ref_exists} refs/symref
+'
+
+test_expect_success '--exists with dangling symref' '
+	test_when_finished "git symbolic-ref -d refs/heads/dangling" &&
+	git symbolic-ref refs/heads/dangling refs/heads/does-not-exist &&
+	${git_show_ref_exists} refs/heads/dangling
+'
+
+test_expect_success '--exists with nonexistent object ID' '
+	test-tool ref-store main update-ref msg refs/heads/missing-oid $(test_oid 001) $ZERO_OID REF_SKIP_OID_VERIFICATION &&
+	${git_show_ref_exists} refs/heads/missing-oid
+'
+
+test_expect_success '--exists with non-commit object' '
+	tree_oid=$(git rev-parse HEAD^{tree}) &&
+	test-tool ref-store main update-ref msg refs/heads/tree ${tree_oid} $ZERO_OID REF_SKIP_OID_VERIFICATION &&
+	${git_show_ref_exists} refs/heads/tree
+'
+
+test_expect_success '--exists with directory fails with generic error' '
+	cat >expect <<-EOF &&
+	error: reference does not exist
+	EOF
+	test_expect_code 2 ${git_show_ref_exists} refs/heads 2>err &&
+	test_cmp expect err
+'
+
+test_expect_success '--exists with non-existent special ref' '
+	test_expect_code 2 ${git_show_ref_exists} FETCH_HEAD
+'
+
+test_expect_success '--exists with existing special ref' '
+	test_when_finished "rm .git/FETCH_HEAD" &&
+	git rev-parse HEAD >.git/FETCH_HEAD &&
+	${git_show_ref_exists} FETCH_HEAD
+'
+
+test_done
diff --git a/t/t1403-show-ref.sh b/t/t1403-show-ref.sh
index 9da3650e91..36c903ca19 100755
--- a/t/t1403-show-ref.sh
+++ b/t/t1403-show-ref.sh
@@ -228,69 +228,4 @@ test_expect_success 'show-ref sub-modes are mutually exclusive' '
 	grep "cannot be used together" err
 '
 
-test_expect_success '--exists with existing reference' '
-	git show-ref --exists refs/heads/$GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
-'
-
-test_expect_success '--exists with missing reference' '
-	test_expect_code 2 git show-ref --exists refs/heads/does-not-exist
-'
-
-test_expect_success '--exists does not use DWIM' '
-	test_expect_code 2 git show-ref --exists $GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME 2>err &&
-	grep "reference does not exist" err
-'
-
-test_expect_success '--exists with HEAD' '
-	git show-ref --exists HEAD
-'
-
-test_expect_success '--exists with bad reference name' '
-	test_when_finished "git update-ref -d refs/heads/bad...name" &&
-	new_oid=$(git rev-parse HEAD) &&
-	test-tool ref-store main update-ref msg refs/heads/bad...name $new_oid $ZERO_OID REF_SKIP_REFNAME_VERIFICATION &&
-	git show-ref --exists refs/heads/bad...name
-'
-
-test_expect_success '--exists with arbitrary symref' '
-	test_when_finished "git symbolic-ref -d refs/symref" &&
-	git symbolic-ref refs/symref refs/heads/$GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME &&
-	git show-ref --exists refs/symref
-'
-
-test_expect_success '--exists with dangling symref' '
-	test_when_finished "git symbolic-ref -d refs/heads/dangling" &&
-	git symbolic-ref refs/heads/dangling refs/heads/does-not-exist &&
-	git show-ref --exists refs/heads/dangling
-'
-
-test_expect_success '--exists with nonexistent object ID' '
-	test-tool ref-store main update-ref msg refs/heads/missing-oid $(test_oid 001) $ZERO_OID REF_SKIP_OID_VERIFICATION &&
-	git show-ref --exists refs/heads/missing-oid
-'
-
-test_expect_success '--exists with non-commit object' '
-	tree_oid=$(git rev-parse HEAD^{tree}) &&
-	test-tool ref-store main update-ref msg refs/heads/tree ${tree_oid} $ZERO_OID REF_SKIP_OID_VERIFICATION &&
-	git show-ref --exists refs/heads/tree
-'
-
-test_expect_success '--exists with directory fails with generic error' '
-	cat >expect <<-EOF &&
-	error: reference does not exist
-	EOF
-	test_expect_code 2 git show-ref --exists refs/heads 2>err &&
-	test_cmp expect err
-'
-
-test_expect_success '--exists with non-existent special ref' '
-	test_expect_code 2 git show-ref --exists FETCH_HEAD
-'
-
-test_expect_success '--exists with existing special ref' '
-	test_when_finished "rm .git/FETCH_HEAD" &&
-	git rev-parse HEAD >.git/FETCH_HEAD &&
-	git show-ref --exists FETCH_HEAD
-'
-
 test_done
diff --git a/t/t1422-show-ref-exists.sh b/t/t1422-show-ref-exists.sh
new file mode 100755
index 0000000000..fdca3f16c8
--- /dev/null
+++ b/t/t1422-show-ref-exists.sh
@@ -0,0 +1,9 @@
+#!/bin/sh
+
+test_description='show-ref --exists'
+GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
+export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
+
+. ./test-lib.sh
+
+. "$TEST_DIRECTORY"/show-ref-exists-tests.sh
diff --git a/t/t1462-refs-exists.sh b/t/t1462-refs-exists.sh
new file mode 100755
index 0000000000..349453c4ca
--- /dev/null
+++ b/t/t1462-refs-exists.sh
@@ -0,0 +1,10 @@
+#!/bin/sh
+
+test_description='refs exists'
+GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
+export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
+
+. ./test-lib.sh
+
+git_show_ref_exists='git refs exists'
+. "$TEST_DIRECTORY"/show-ref-exists-tests.sh