test-tool: add the path-walk subcommand

This is currently primarily here for me to test out a couple of ideas or
to investigate how this path walk API thing works.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Makefile

@@ -822,6 +822,7 @@ TEST_BUILTINS_OBJS += test-parse-options.o
 TEST_BUILTINS_OBJS += test-parse-pathspec-file.o
 TEST_BUILTINS_OBJS += test-partial-clone.o
 TEST_BUILTINS_OBJS += test-path-utils.o
+TEST_BUILTINS_OBJS += test-path-walk.o
 TEST_BUILTINS_OBJS += test-pcre2-config.o
 TEST_BUILTINS_OBJS += test-pkt-line.o
 TEST_BUILTINS_OBJS += test-proc-receive.o

t/helper/test-path-walk.c

@@ -0,0 +1,67 @@
+#define USE_THE_REPOSITORY_VARIABLE
+
+#include "test-tool.h"
+#include "git-compat-util.h"
+#include "parse-options.h"
+#include "setup.h"
+#include "revision.h"
+#include "path-walk.h"
+#include "oid-array.h"
+#include "hex.h"
+
+static const char * const path_walk_usage[] = {
+	N_("test-tool path-walk <options>"),
+	NULL
+};
+
+static int verbose;
+
+static int callback_fn(const char *path,
+		       struct oid_array *list,
+		       enum object_type type,
+		       void *data)
+{
+	printf("visiting path '%s' (count: %"PRIuMAX") of type '%s'\n",
+		path, list->nr, type_name(type));
+	if (verbose)
+		for (size_t i = 0; i < list->nr; i++)
+			printf("\t%s\n", oid_to_hex(list->oid + i));
+
+	return 0;
+}
+
+int cmd__path_walk(int argc, const char **argv)
+{
+	struct rev_info revs;
+	struct path_walk_info info = PATH_WALK_INFO_INIT;
+	struct option options[] = {
+		OPT_BOOL(0, "tags", &info.tags, N_("walk tags")),
+		OPT_BOOL(0, "commits", &info.commits, N_("walk commits")),
+		OPT_BOOL(0, "trees", &info.trees, N_("walk trees")),
+		OPT_BOOL(0, "blobs", &info.blobs, N_("walk blobs")),
+		OPT__VERBOSE(&verbose, N_("verbose")),
+		OPT_END(),
+	};
+	int ret = 0;
+
+	if (argc == 2 && !strcmp(argv[1], "-h"))
+		usage_with_options(path_walk_usage, options);
+
+	argc = parse_options(argc, argv, NULL, options, path_walk_usage,
+			     PARSE_OPT_KEEP_ARGV0);
+
+	setup_git_directory();
+
+	repo_init_revisions(the_repository, &revs, "");
+	setup_revisions(argc, argv, &revs, NULL);
+
+	info.revs = &revs;
+	info.path_fn = callback_fn;
+
+	ret = walk_objects_by_path(&info);
+
+	reset_revision_walk();
+	release_revisions(&revs);
+
+	return ret;
+}

t/helper/test-tool.c

@@ -54,6 +54,7 @@ static struct test_cmd cmds[] = {
 	{ "parse-subcommand", cmd__parse_subcommand },
 	{ "partial-clone", cmd__partial_clone },
 	{ "path-utils", cmd__path_utils },
+	{ "path-walk", cmd__path_walk },
 	{ "pcre2-config", cmd__pcre2_config },
 	{ "pkt-line", cmd__pkt_line },
 	{ "proc-receive", cmd__proc_receive },

t/helper/test-tool.h

@@ -47,6 +47,7 @@ int cmd__parse_pathspec_file(int argc, const char** argv);
 int cmd__parse_subcommand(int argc, const char **argv);
 int cmd__partial_clone(int argc, const char **argv);
 int cmd__path_utils(int argc, const char **argv);
+int cmd__path_walk(int argc, const char **argv);
 int cmd__pcre2_config(int argc, const char **argv);
 int cmd__pkt_line(int argc, const char **argv);
 int cmd__proc_receive(int argc, const char **argv);