Test obtain_device_info for ZyXEL WSM20 using the dual-flag method with a
custom MTD partition ("persist") and byte offset (4).
Partition 1 active (the flag byte at offset 4 reads "01", matching partition 1).

-- File fs/open~_tmp_sysinfo_board_name.txt --
zyxel,wsm20
-- End --

-- File fs/popen~_lib_functions_sh_find_mtd_part_persist_.txt --
/dev/mtdblock7
-- End --

-- File fs/popen~dd_if_dev_mtdblock7_bs_1_count_1_skip_4_2_dev_null_hexdump_-n_1_-e_1_1_02x_.txt --
01
-- End --

-- File fs/popen~_etc_os-release_2_dev_null_echo_OPENWRT_RELEASE_2_dev_null.txt --
OpenWrt 25.12.2 r32802-f505120278
-- End --

-- File fs/open~_proc_version.txt --
Linux version 6.12.74 (builder@buildhost) (mipsel-openwrt-linux-musl-gcc) #0
-- End --

-- File fs/popen~dd_if_dev_mtd6_bs_1_skip_32_count_64.txt --
Linux-6.6.50 ZyXEL
-- End --

-- Testcase --
let ar = require('advanced_reboot');
let api = ar["luci.advanced-reboot"];
let result = api.obtain_device_info.call();

printf("vendor: %s\n", result.device.vendor);
printf("model: %s\n", result.device.model);
printf("board: %s\n", result.device.board);
printf("active: %s\n", result.device.partition_active);
printf("partitions: %d\n", length(result.partitions));

let p1 = result.partitions[0];
printf("p1: number=%s label=%s os=%s\n", p1.number, p1.label, p1.os);

let p2 = result.partitions[1];
printf("p2: number=%s label=%s os=%s\n", p2.number, p2.label, p2.os);
-- End --

-- Expect stdout --
vendor: ZyXEL
model: WSM20
board: zyxel,wsm20
active: 1
partitions: 2
p1: number=1 label=OpenWrt 25.12.2 r32802-f505120278 os=6.12.74
p2: number=2 label=ZyXEL os=6.6.50
-- End --