t/helper: add test-submodule-nested-repo-config

Add a test tool to exercise config_from_gitmodules(), in particular for
the case of nested submodules.

Add also a test to document that reading the submoudles config of nested
submodules does not work yet when the .gitmodules file is not in the
working tree but it still in the index.

This is because the git API does not always make it possible access the
object store  of an arbitrary repository (see get_oid() usage in
config_from_gitmodules()).

When this git limitation gets fixed the aforementioned use case will be
supported too.

Signed-off-by: Antonio Ospite <ao2@ao2.it>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -735,6 +735,7 @@ TEST_BUILTINS_OBJS += test-sigchain.o
 TEST_BUILTINS_OBJS += test-strcmp-offset.o
 TEST_BUILTINS_OBJS += test-string-list.o
 TEST_BUILTINS_OBJS += test-submodule-config.o
+TEST_BUILTINS_OBJS += test-submodule-nested-repo-config.o
 TEST_BUILTINS_OBJS += test-subprocess.o
 TEST_BUILTINS_OBJS += test-urlmatch-normalization.o
 TEST_BUILTINS_OBJS += test-wildmatch.o

t/helper/test-submodule-nested-repo-config.c

@@ -0,0 +1,30 @@
+#include "test-tool.h"
+#include "submodule-config.h"
+
+static void die_usage(int argc, const char **argv, const char *msg)
+{
+	fprintf(stderr, "%s\n", msg);
+	fprintf(stderr, "Usage: %s <submodulepath> <config name>\n", argv[0]);
+	exit(1);
+}
+
+int cmd__submodule_nested_repo_config(int argc, const char **argv)
+{
+	struct repository submodule;
+
+	if (argc < 3)
+		die_usage(argc, argv, "Wrong number of arguments.");
+
+	setup_git_directory();
+
+	if (repo_submodule_init(&submodule, the_repository, argv[1])) {
+		die_usage(argc, argv, "Submodule not found.");
+	}
+
+	/* Read the config of _child_ submodules. */
+	print_config_from_gitmodules(&submodule, argv[2]);
+
+	submodule_free(the_repository);
+
+	return 0;
+}

t/helper/test-tool.c

@@ -40,6 +40,7 @@ static struct test_cmd cmds[] = {
 	{ "strcmp-offset", cmd__strcmp_offset },
 	{ "string-list", cmd__string_list },
 	{ "submodule-config", cmd__submodule_config },
+	{ "submodule-nested-repo-config", cmd__submodule_nested_repo_config },
 	{ "subprocess", cmd__subprocess },
 	{ "urlmatch-normalization", cmd__urlmatch_normalization },
 	{ "wildmatch", cmd__wildmatch },

t/helper/test-tool.h

@@ -36,6 +36,7 @@ int cmd__sigchain(int argc, const char **argv);
 int cmd__strcmp_offset(int argc, const char **argv);
 int cmd__string_list(int argc, const char **argv);
 int cmd__submodule_config(int argc, const char **argv);
+int cmd__submodule_nested_repo_config(int argc, const char **argv);
 int cmd__subprocess(int argc, const char **argv);
 int cmd__urlmatch_normalization(int argc, const char **argv);
 int cmd__wildmatch(int argc, const char **argv);

t/t7411-submodule-config.sh

@@ -216,4 +216,38 @@ test_expect_success 'reading submodules config from the current branch when .git
 	)
 '
 
+test_expect_success 'reading nested submodules config' '
+	(cd super &&
+		git init submodule/nested_submodule &&
+		echo "a" >submodule/nested_submodule/a &&
+		git -C submodule/nested_submodule add a &&
+		git -C submodule/nested_submodule commit -m "add a" &&
+		git -C submodule submodule add ./nested_submodule &&
+		git -C submodule add nested_submodule &&
+		git -C submodule commit -m "added nested_submodule" &&
+		git add submodule &&
+		git commit -m "updated submodule" &&
+		echo "./nested_submodule" >expect &&
+		test-tool submodule-nested-repo-config \
+			submodule submodule.nested_submodule.url >actual &&
+		test_cmp expect actual
+	)
+'
+
+# When this test eventually passes, before turning it into
+# test_expect_success, remember to replace the test_i18ngrep below with
+# a "test_must_be_empty warning" to be sure that the warning is actually
+# removed from the code.
+test_expect_failure 'reading nested submodules config when .gitmodules is not in the working tree' '
+	test_when_finished "git -C super/submodule checkout .gitmodules" &&
+	(cd super &&
+		echo "./nested_submodule" >expect &&
+		rm submodule/.gitmodules &&
+		test-tool submodule-nested-repo-config \
+			submodule submodule.nested_submodule.url >actual 2>warning &&
+		test_i18ngrep "nested submodules without %s in the working tree are not supported yet" warning &&
+		test_cmp expect actual
+	)
+'
+
 test_done