Turn `git serve` into a test helper

The `git serve` built-in was introduced in ed10cb952d31 (serve:
introduce git-serve, 2018-03-15) as a backend to serve Git protocol v2,
probably originally intended to be spawned by `git upload-pack`.

However, in the version that the protocol v2 patches made it into core
Git, `git upload-pack` calls the `serve()` function directly instead of
spawning `git serve`; The only reason in life for `git serve` to survive
as a built-in command is to provide a way to test the protocol v2
functionality.

Meaning that it does not even have to be a built-in that is installed
with end-user facing Git installations, but it can be a test helper
instead.

Let's make it so.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

9 files changed, 36 insertions, 30 deletions

diff --git a/Makefile b/Makefile
index f5fc977ee8..9ce62fa295 100644
--- a/Makefile
+++ b/Makefile
@@ -758,6 +758,7 @@ TEST_BUILTINS_OBJS += test-repository.o
 TEST_BUILTINS_OBJS += test-revision-walking.o
 TEST_BUILTINS_OBJS += test-run-command.o
 TEST_BUILTINS_OBJS += test-scrap-cache-tree.o
+TEST_BUILTINS_OBJS += test-serve-v2.o
 TEST_BUILTINS_OBJS += test-sha1.o
 TEST_BUILTINS_OBJS += test-sha1-array.o
 TEST_BUILTINS_OBJS += test-sha256.o
@@ -1127,7 +1128,6 @@ BUILTIN_OBJS += builtin/rev-parse.o
 BUILTIN_OBJS += builtin/revert.o
 BUILTIN_OBJS += builtin/rm.o
 BUILTIN_OBJS += builtin/send-pack.o
-BUILTIN_OBJS += builtin/serve.o
 BUILTIN_OBJS += builtin/shortlog.o
 BUILTIN_OBJS += builtin/show-branch.o
 BUILTIN_OBJS += builtin/show-index.o
diff --git a/builtin.h b/builtin.h
index 6538932e99..c48636e244 100644
--- a/builtin.h
+++ b/builtin.h
@@ -219,7 +219,6 @@ extern int cmd_rev_parse(int argc, const char **argv, const char *prefix);
 extern int cmd_revert(int argc, const char **argv, const char *prefix);
 extern int cmd_rm(int argc, const char **argv, const char *prefix);
 extern int cmd_send_pack(int argc, const char **argv, const char *prefix);
-extern int cmd_serve(int argc, const char **argv, const char *prefix);
 extern int cmd_shortlog(int argc, const char **argv, const char *prefix);
 extern int cmd_show(int argc, const char **argv, const char *prefix);
 extern int cmd_show_branch(int argc, const char **argv, const char *prefix);
diff --git a/git.c b/git.c
index 2dd588674f..c58b067771 100644
--- a/git.c
+++ b/git.c
@@ -548,7 +548,6 @@ static struct cmd_struct commands[] = {
 	{ "revert", cmd_revert, RUN_SETUP | NEED_WORK_TREE },
 	{ "rm", cmd_rm, RUN_SETUP },
 	{ "send-pack", cmd_send_pack, RUN_SETUP },
-	{ "serve", cmd_serve, RUN_SETUP },
 	{ "shortlog", cmd_shortlog, RUN_SETUP_GENTLY | USE_PAGER },
 	{ "show", cmd_show, RUN_SETUP },
 	{ "show-branch", cmd_show_branch, RUN_SETUP },
diff --git a/builtin/serve.c b/t/helper/test-serve-v2.c
index d3fd240bb3..aee35e5aef 100644
--- a/builtin/serve.c
+++ b/t/helper/test-serve-v2.c
@@ -1,14 +1,14 @@
+#include "test-tool.h"
 #include "cache.h"
-#include "builtin.h"
 #include "parse-options.h"
 #include "serve.h"
 
 static char const * const serve_usage[] = {
-	N_("git serve [<options>]"),
+	N_("test-tool serve-v2 [<options>]"),
 	NULL
 };
 
-int cmd_serve(int argc, const char **argv, const char *prefix)
+int cmd__serve_v2(int argc, const char **argv)
 {
 	struct serve_options opts = SERVE_OPTIONS_INIT;
 
@@ -19,6 +19,7 @@ int cmd_serve(int argc, const char **argv, const char *prefix)
 			 N_("exit immediately after advertising capabilities")),
 		OPT_END()
 	};
+	const char *prefix = setup_git_directory();
 
 	/* ignore all unknown cmdline switches for now */
 	argc = parse_options(argc, argv, prefix, options, serve_usage,
diff --git a/t/helper/test-tool.c b/t/helper/test-tool.c
index 2b21943f93..4bf3666b43 100644
--- a/t/helper/test-tool.c
+++ b/t/helper/test-tool.c
@@ -48,6 +48,7 @@ static struct test_cmd cmds[] = {
 	{ "revision-walking", cmd__revision_walking },
 	{ "run-command", cmd__run_command },
 	{ "scrap-cache-tree", cmd__scrap_cache_tree },
+	{ "serve-v2", cmd__serve_v2 },
 	{ "sha1", cmd__sha1 },
 	{ "sha1-array", cmd__sha1_array },
 	{ "sha256", cmd__sha256 },
diff --git a/t/helper/test-tool.h b/t/helper/test-tool.h
index 25abed1cf2..bc72370916 100644
--- a/t/helper/test-tool.h
+++ b/t/helper/test-tool.h
@@ -39,6 +39,7 @@ int cmd__repository(int argc, const char **argv);
 int cmd__revision_walking(int argc, const char **argv);
 int cmd__run_command(int argc, const char **argv);
 int cmd__scrap_cache_tree(int argc, const char **argv);
+int cmd__serve_v2(int argc, const char **argv);
 int cmd__sha1(int argc, const char **argv);
 int cmd__sha1_array(int argc, const char **argv);
 int cmd__sha256(int argc, const char **argv);
diff --git a/t/t5701-git-serve.sh b/t/t5701-git-serve.sh
index fe45bf828d..ffb9613885 100755
--- a/t/t5701-git-serve.sh
+++ b/t/t5701-git-serve.sh
@@ -1,6 +1,6 @@
 #!/bin/sh
 
-test_description='test git-serve and server commands'
+test_description='test protocol v2 server commands'
 
 . ./test-lib.sh
 
@@ -14,7 +14,8 @@ test_expect_success 'test capability advertisement' '
 	0000
 	EOF
 
-	GIT_TEST_SIDEBAND_ALL=0 git serve --advertise-capabilities >out &&
+	GIT_TEST_SIDEBAND_ALL=0 test-tool serve-v2 \
+		--advertise-capabilities >out &&
 	test-tool pkt-line unpack <out >actual &&
 	test_cmp expect actual
 '
@@ -24,11 +25,11 @@ test_expect_success 'stateless-rpc flag does not list capabilities' '
 	test-tool pkt-line pack >in <<-EOF &&
 	0000
 	EOF
-	git serve --stateless-rpc >out <in &&
+	test-tool serve-v2 --stateless-rpc >out <in &&
 	test_must_be_empty out &&
 
 	# EOF
-	git serve --stateless-rpc >out &&
+	test-tool serve-v2 --stateless-rpc >out &&
 	test_must_be_empty out
 '
 
@@ -37,7 +38,7 @@ test_expect_success 'request invalid capability' '
 	foobar
 	0000
 	EOF
-	test_must_fail git serve --stateless-rpc 2>err <in &&
+	test_must_fail test-tool serve-v2 --stateless-rpc 2>err <in &&
 	test_i18ngrep "unknown capability" err
 '
 
@@ -46,7 +47,7 @@ test_expect_success 'request with no command' '
 	agent=git/test
 	0000
 	EOF
-	test_must_fail git serve --stateless-rpc 2>err <in &&
+	test_must_fail test-tool serve-v2 --stateless-rpc 2>err <in &&
 	test_i18ngrep "no command requested" err
 '
 
@@ -56,7 +57,7 @@ test_expect_success 'request invalid command' '
 	agent=git/test
 	0000
 	EOF
-	test_must_fail git serve --stateless-rpc 2>err <in &&
+	test_must_fail test-tool serve-v2 --stateless-rpc 2>err <in &&
 	test_i18ngrep "invalid command" err
 '
 
@@ -87,7 +88,7 @@ test_expect_success 'basics of ls-refs' '
 	0000
 	EOF
 
-	git serve --stateless-rpc <in >out &&
+	test-tool serve-v2 --stateless-rpc <in >out &&
 	test-tool pkt-line unpack <out >actual &&
 	test_cmp expect actual
 '
@@ -107,7 +108,7 @@ test_expect_success 'basic ref-prefixes' '
 	0000
 	EOF
 
-	git serve --stateless-rpc <in >out &&
+	test-tool serve-v2 --stateless-rpc <in >out &&
 	test-tool pkt-line unpack <out >actual &&
 	test_cmp expect actual
 '
@@ -127,7 +128,7 @@ test_expect_success 'refs/heads prefix' '
 	0000
 	EOF
 
-	git serve --stateless-rpc <in >out &&
+	test-tool serve-v2 --stateless-rpc <in >out &&
 	test-tool pkt-line unpack <out >actual &&
 	test_cmp expect actual
 '
@@ -148,7 +149,7 @@ test_expect_success 'peel parameter' '
 	0000
 	EOF
 
-	git serve --stateless-rpc <in >out &&
+	test-tool serve-v2 --stateless-rpc <in >out &&
 	test-tool pkt-line unpack <out >actual &&
 	test_cmp expect actual
 '
@@ -169,7 +170,7 @@ test_expect_success 'symrefs parameter' '
 	0000
 	EOF
 
-	git serve --stateless-rpc <in >out &&
+	test-tool serve-v2 --stateless-rpc <in >out &&
 	test-tool pkt-line unpack <out >actual &&
 	test_cmp expect actual
 '
@@ -189,7 +190,7 @@ test_expect_success 'sending server-options' '
 	0000
 	EOF
 
-	git serve --stateless-rpc <in >out &&
+	test-tool serve-v2 --stateless-rpc <in >out &&
 	test-tool pkt-line unpack <out >actual &&
 	test_cmp expect actual
 '
@@ -204,7 +205,10 @@ test_expect_success 'unexpected lines are not allowed in fetch request' '
 	0000
 	EOF
 
-	test_must_fail git -C server serve --stateless-rpc <in >/dev/null 2>err &&
+	(
+		cd server &&
+		test_must_fail test-tool serve-v2 --stateless-rpc
+	) <in >/dev/null 2>err &&
 	grep "unexpected line: .this-is-not-a-command." err
 '
 
diff --git a/t/t5702-protocol-v2.sh b/t/t5702-protocol-v2.sh
index db4ae09f2f..8691bfc52d 100755
--- a/t/t5702-protocol-v2.sh
+++ b/t/t5702-protocol-v2.sh
@@ -359,12 +359,13 @@ test_expect_success 'even with handcrafted request, filter does not work if not
 	0000
 	EOF
 
-	test_must_fail git -C server serve --stateless-rpc <in >/dev/null 2>err &&
+	test_must_fail test-tool -C server serve-v2 --stateless-rpc \
+		<in >/dev/null 2>err &&
 	grep "unexpected line: .filter blob:none." err &&
 
 	# Exercise to ensure that if advertised, filter works
 	git -C server config uploadpack.allowfilter 1 &&
-	git -C server serve --stateless-rpc <in >/dev/null
+	test-tool -C server serve-v2 --stateless-rpc <in >/dev/null
 '
 
 test_expect_success 'default refspec is used to filter ref when fetchcing' '
diff --git a/t/t5703-upload-pack-ref-in-want.sh b/t/t5703-upload-pack-ref-in-want.sh
index f87b2f6df3..dd1cbd0dd6 100755
--- a/t/t5703-upload-pack-ref-in-want.sh
+++ b/t/t5703-upload-pack-ref-in-want.sh
@@ -48,15 +48,15 @@ test_expect_success 'setup repository' '
 '
 
 test_expect_success 'config controls ref-in-want advertisement' '
-	git serve --advertise-capabilities >out &&
+	test-tool serve-v2 --advertise-capabilities >out &&
 	! grep -a ref-in-want out &&
 
 	git config uploadpack.allowRefInWant false &&
-	git serve --advertise-capabilities >out &&
+	test-tool serve-v2 --advertise-capabilities >out &&
 	! grep -a ref-in-want out &&
 
 	git config uploadpack.allowRefInWant true &&
-	git serve --advertise-capabilities >out &&
+	test-tool serve-v2 --advertise-capabilities >out &&
 	grep -a ref-in-want out
 '
 
@@ -70,7 +70,7 @@ test_expect_success 'invalid want-ref line' '
 	0000
 	EOF
 
-	test_must_fail git serve --stateless-rpc 2>out <in &&
+	test_must_fail test-tool serve-v2 --stateless-rpc 2>out <in &&
 	grep "unknown ref" out
 '
 
@@ -90,7 +90,7 @@ test_expect_success 'basic want-ref' '
 	0000
 	EOF
 
-	git serve --stateless-rpc >out <in &&
+	test-tool serve-v2 --stateless-rpc >out <in &&
 	check_output
 '
 
@@ -112,7 +112,7 @@ test_expect_success 'multiple want-ref lines' '
 	0000
 	EOF
 
-	git serve --stateless-rpc >out <in &&
+	test-tool serve-v2 --stateless-rpc >out <in &&
 	check_output
 '
 
@@ -133,7 +133,7 @@ test_expect_success 'mix want and want-ref' '
 	0000
 	EOF
 
-	git serve --stateless-rpc >out <in &&
+	test-tool serve-v2 --stateless-rpc >out <in &&
 	check_output
 '
 
@@ -153,7 +153,7 @@ test_expect_success 'want-ref with ref we already have commit for' '
 	0000
 	EOF
 
-	git serve --stateless-rpc >out <in &&
+	test-tool serve-v2 --stateless-rpc >out <in &&
 	check_output
 '