t6601: add helper for testing path-walk API

Add some tests based on the current behavior, doing interesting checks
for different sets of branches, ranges, and the --boundary option. This
sets a baseline for the behavior and we can extend it as new options are
introduced.

It is important to mention that the behavior of the API will change soon as
we start to handle UNINTERESTING objects differently, but these tests will
demonstrate the change in behavior.

Signed-off-by: Derrick Stolee <stolee@gmail.com>

Documentation/technical/api-path-walk.txt

@@ -42,4 +42,5 @@ commits.
 Examples
 --------
 
-See example usages in future changes.
+See example usages in:
+	`t/helper/test-path-walk.c`

Makefile

@@ -818,6 +818,7 @@ 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 +1,86 @@
+#define USE_THE_REPOSITORY_VARIABLE
+
+#include "test-tool.h"
+#include "environment.h"
+#include "hex.h"
+#include "object-name.h"
+#include "object.h"
+#include "pretty.h"
+#include "revision.h"
+#include "setup.h"
+#include "parse-options.h"
+#include "path-walk.h"
+#include "oid-array.h"
+
+static const char * const path_walk_usage[] = {
+	N_("test-tool path-walk <options> -- <revision-options>"),
+	NULL
+};
+
+struct path_walk_test_data {
+	uintmax_t tree_nr;
+	uintmax_t blob_nr;
+};
+
+static int emit_block(const char *path, struct oid_array *oids,
+		      enum object_type type, void *data)
+{
+	struct path_walk_test_data *tdata = data;
+	const char *typestr;
+
+	switch (type) {
+	case OBJ_TREE:
+		typestr = "TREE";
+		tdata->tree_nr += oids->nr;
+		break;
+
+	case OBJ_BLOB:
+		typestr = "BLOB";
+		tdata->blob_nr += oids->nr;
+		break;
+
+	default:
+		BUG("we do not understand this type");
+	}
+
+	for (size_t i = 0; i < oids->nr; i++)
+		printf("%s:%s:%s\n", typestr, path, oid_to_hex(&oids->oid[i]));
+
+	return 0;
+}
+
+int cmd__path_walk(int argc, const char **argv)
+{
+	int res;
+	struct rev_info revs = REV_INFO_INIT;
+	struct path_walk_info info = PATH_WALK_INFO_INIT;
+	struct path_walk_test_data data = { 0 };
+	struct option options[] = {
+		OPT_END(),
+	};
+
+	initialize_repository(the_repository);
+	setup_git_directory();
+	revs.repo = the_repository;
+
+	argc = parse_options(argc, argv, NULL,
+			     options, path_walk_usage,
+			     PARSE_OPT_KEEP_UNKNOWN_OPT | PARSE_OPT_KEEP_ARGV0);
+
+	if (argc > 1)
+		setup_revisions(argc, argv, &revs, NULL);
+	else
+		usage(path_walk_usage[0]);
+
+	info.revs = &revs;
+	info.path_fn = emit_block;
+	info.path_fn_data = &data;
+
+	res = walk_objects_by_path(&info);
+
+	printf("trees:%" PRIuMAX "\n"
+	       "blobs:%" PRIuMAX "\n",
+	       data.tree_nr, data.blob_nr);
+
+	return res;
+}

t/helper/test-tool.c

@@ -52,6 +52,7 @@ 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

@@ -45,6 +45,7 @@ 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);

t/t6601-path-walk.sh

@@ -0,0 +1,118 @@
+#!/bin/sh
+
+test_description='direct path-walk API tests'
+
+. ./test-lib.sh
+
+test_expect_success 'setup test repository' '
+	git checkout -b base &&
+
+	mkdir left &&
+	mkdir right &&
+	echo a >a &&
+	echo b >left/b &&
+	echo c >right/c &&
+	git add . &&
+	git commit -m "first" &&
+
+	echo d >right/d &&
+	git add right &&
+	git commit -m "second" &&
+
+	echo bb >left/b &&
+	git commit -a -m "third" &&
+
+	git checkout -b topic HEAD~1 &&
+	echo cc >right/c &&
+	git commit -a -m "topic"
+'
+
+test_expect_success 'all' '
+	test-tool path-walk -- --all >out &&
+
+	cat >expect <<-EOF &&
+	TREE::$(git rev-parse topic^{tree})
+	TREE::$(git rev-parse base^{tree})
+	TREE::$(git rev-parse base~1^{tree})
+	TREE::$(git rev-parse base~2^{tree})
+	TREE:left/:$(git rev-parse base:left)
+	TREE:left/:$(git rev-parse base~2:left)
+	TREE:right/:$(git rev-parse topic:right)
+	TREE:right/:$(git rev-parse base~1:right)
+	TREE:right/:$(git rev-parse base~2:right)
+	trees:9
+	BLOB:a:$(git rev-parse base~2:a)
+	BLOB:left/b:$(git rev-parse base~2:left/b)
+	BLOB:left/b:$(git rev-parse base:left/b)
+	BLOB:right/c:$(git rev-parse base~2:right/c)
+	BLOB:right/c:$(git rev-parse topic:right/c)
+	BLOB:right/d:$(git rev-parse base~1:right/d)
+	blobs:6
+	EOF
+
+	test_cmp_sorted expect out
+'
+
+test_expect_success 'topic only' '
+	test-tool path-walk -- topic >out &&
+
+	cat >expect <<-EOF &&
+	TREE::$(git rev-parse topic^{tree})
+	TREE::$(git rev-parse base~1^{tree})
+	TREE::$(git rev-parse base~2^{tree})
+	TREE:left/:$(git rev-parse base~2:left)
+	TREE:right/:$(git rev-parse topic:right)
+	TREE:right/:$(git rev-parse base~1:right)
+	TREE:right/:$(git rev-parse base~2:right)
+	trees:7
+	BLOB:a:$(git rev-parse base~2:a)
+	BLOB:left/b:$(git rev-parse base~2:left/b)
+	BLOB:right/c:$(git rev-parse base~2:right/c)
+	BLOB:right/c:$(git rev-parse topic:right/c)
+	BLOB:right/d:$(git rev-parse base~1:right/d)
+	blobs:5
+	EOF
+
+	test_cmp_sorted expect out
+'
+
+test_expect_success 'topic, not base' '
+	test-tool path-walk -- topic --not base >out &&
+
+	cat >expect <<-EOF &&
+	TREE::$(git rev-parse topic^{tree})
+	TREE:left/:$(git rev-parse topic:left)
+	TREE:right/:$(git rev-parse topic:right)
+	trees:3
+	BLOB:a:$(git rev-parse topic:a)
+	BLOB:left/b:$(git rev-parse topic:left/b)
+	BLOB:right/c:$(git rev-parse topic:right/c)
+	BLOB:right/d:$(git rev-parse topic:right/d)
+	blobs:4
+	EOF
+
+	test_cmp_sorted expect out
+'
+
+test_expect_success 'topic, not base, boundary' '
+	test-tool path-walk -- --boundary topic --not base >out &&
+
+	cat >expect <<-EOF &&
+	TREE::$(git rev-parse topic^{tree})
+	TREE::$(git rev-parse base~1^{tree})
+	TREE:left/:$(git rev-parse base~1:left)
+	TREE:right/:$(git rev-parse topic:right)
+	TREE:right/:$(git rev-parse base~1:right)
+	trees:5
+	BLOB:a:$(git rev-parse base~1:a)
+	BLOB:left/b:$(git rev-parse base~1:left/b)
+	BLOB:right/c:$(git rev-parse base~1:right/c)
+	BLOB:right/c:$(git rev-parse topic:right/c)
+	BLOB:right/d:$(git rev-parse base~1:right/d)
+	blobs:5
+	EOF
+
+	test_cmp_sorted expect out
+'
+
+test_done