unit-serialization.cpp

//     __ _____ _____ _____
//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
// |  |  |__   |  |  | | | |  version 3.12.0
// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
//
// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
// SPDX-License-Identifier: MIT

#include "doctest_compatibility.h"

#include <nlohmann/json.hpp>
using nlohmann::json;

#include <array>
#include <sstream>
#include <iomanip>

TEST_CASE("serialization")
{
    SECTION("operator<<")
    {
        SECTION("no given width")
        {
            std::stringstream ss;
            const json j = {"foo", 1, 2, 3, false, {{"one", 1}}};
            ss << j;
            CHECK(ss.str() == "[\"foo\",1,2,3,false,{\"one\":1}]");
        }

        SECTION("given width")
        {
            std::stringstream ss;
            const json j = {"foo", 1, 2, 3, false, {{"one", 1}}};
            ss << std::setw(4) << j;
            CHECK(ss.str() ==
                  "[\n    \"foo\",\n    1,\n    2,\n    3,\n    false,\n    {\n        \"one\": 1\n    }\n]");
        }

        SECTION("given fill")
        {
            std::stringstream ss;
            const json j = {"foo", 1, 2, 3, false, {{"one", 1}}};
            ss << std::setw(1) << std::setfill('\t') << j;
            CHECK(ss.str() ==
                  "[\n\t\"foo\",\n\t1,\n\t2,\n\t3,\n\tfalse,\n\t{\n\t\t\"one\": 1\n\t}\n]");
        }
    }

    SECTION("operator>>")
    {
        SECTION("no given width")
        {
            std::stringstream ss;
            const json j = {"foo", 1, 2, 3, false, {{"one", 1}}};
            j >> ss;
            CHECK(ss.str() == "[\"foo\",1,2,3,false,{\"one\":1}]");
        }

        SECTION("given width")
        {
            std::stringstream ss;
            const json j = {"foo", 1, 2, 3, false, {{"one", 1}}};
            ss.width(4);
            j >> ss;
            CHECK(ss.str() ==
                  "[\n    \"foo\",\n    1,\n    2,\n    3,\n    false,\n    {\n        \"one\": 1\n    }\n]");
        }

        SECTION("given fill")
        {
            std::stringstream ss;
            const json j = {"foo", 1, 2, 3, false, {{"one", 1}}};
            ss.width(1);
            ss.fill('\t');
            j >> ss;
            CHECK(ss.str() ==
                  "[\n\t\"foo\",\n\t1,\n\t2,\n\t3,\n\tfalse,\n\t{\n\t\t\"one\": 1\n\t}\n]");
        }
    }

    SECTION("dump")
    {
        SECTION("invalid character")
        {
            const json j = "ä\xA9ü";

            CHECK_THROWS_WITH_AS(j.dump(), "[json.exception.type_error.316] invalid UTF-8 byte at index 2: 0xA9", json::type_error&);
            CHECK_THROWS_WITH_AS(j.dump(1, ' ', false, json::error_handler_t::strict), "[json.exception.type_error.316] invalid UTF-8 byte at index 2: 0xA9", json::type_error&);
            CHECK(j.dump(-1, ' ', false, json::error_handler_t::ignore) == "\"äü\"");
            CHECK(j.dump(-1, ' ', false, json::error_handler_t::replace) == "\"ä\xEF\xBF\xBDü\"");
            CHECK(j.dump(-1, ' ', true, json::error_handler_t::replace) == "\"\\u00e4\\ufffd\\u00fc\"");
        }

        SECTION("ending with incomplete character")
        {
            const json j = "123\xC2";

            CHECK_THROWS_WITH_AS(j.dump(), "[json.exception.type_error.316] incomplete UTF-8 string; last byte: 0xC2", json::type_error&);
            CHECK_THROWS_AS(j.dump(1, ' ', false, json::error_handler_t::strict), json::type_error&);
            CHECK(j.dump(-1, ' ', false, json::error_handler_t::ignore) == "\"123\"");
            CHECK(j.dump(-1, ' ', false, json::error_handler_t::replace) == "\"123\xEF\xBF\xBD\"");
            CHECK(j.dump(-1, ' ', true, json::error_handler_t::replace) == "\"123\\ufffd\"");
        }

        SECTION("unexpected character")
        {
            const json j = "123\xF1\xB0\x34\x35\x36";

            CHECK_THROWS_WITH_AS(j.dump(), "[json.exception.type_error.316] invalid UTF-8 byte at index 5: 0x34", json::type_error&);
            CHECK_THROWS_AS(j.dump(1, ' ', false, json::error_handler_t::strict), json::type_error&);
            CHECK(j.dump(-1, ' ', false, json::error_handler_t::ignore) == "\"123456\"");
            CHECK(j.dump(-1, ' ', false, json::error_handler_t::replace) == "\"123\xEF\xBF\xBD\x34\x35\x36\"");
            CHECK(j.dump(-1, ' ', true, json::error_handler_t::replace) == "\"123\\ufffd456\"");
        }

        SECTION("U+FFFD Substitution of Maximal Subparts")
        {
            // Some tests (mostly) from
            // https://www.unicode.org/versions/Unicode11.0.0/ch03.pdf
            // Section 3.9 -- U+FFFD Substitution of Maximal Subparts

            auto test = [&](std::string const & input, std::string const & expected)
            {
                const json j = input;
                CHECK(j.dump(-1, ' ', true, json::error_handler_t::replace) == "\"" + expected + "\"");
            };

            test("\xC2", "\\ufffd");
            test("\xC2\x41\x42", "\\ufffd" "\x41" "\x42");
            test("\xC2\xF4", "\\ufffd" "\\ufffd");

            test("\xF0\x80\x80\x41", "\\ufffd" "\\ufffd" "\\ufffd" "\x41");
            test("\xF1\x80\x80\x41", "\\ufffd" "\x41");
            test("\xF2\x80\x80\x41", "\\ufffd" "\x41");
            test("\xF3\x80\x80\x41", "\\ufffd" "\x41");
            test("\xF4\x80\x80\x41", "\\ufffd" "\x41");
            test("\xF5\x80\x80\x41", "\\ufffd" "\\ufffd" "\\ufffd" "\x41");

            test("\xF0\x90\x80\x41", "\\ufffd" "\x41");
            test("\xF1\x90\x80\x41", "\\ufffd" "\x41");
            test("\xF2\x90\x80\x41", "\\ufffd" "\x41");
            test("\xF3\x90\x80\x41", "\\ufffd" "\x41");
            test("\xF4\x90\x80\x41", "\\ufffd" "\\ufffd" "\\ufffd" "\x41");
            test("\xF5\x90\x80\x41", "\\ufffd" "\\ufffd" "\\ufffd" "\x41");

            test("\xC0\xAF\xE0\x80\xBF\xF0\x81\x82\x41", "\\ufffd" "\\ufffd" "\\ufffd" "\\ufffd" "\\ufffd" "\\ufffd" "\\ufffd" "\\ufffd" "\x41");
            test("\xED\xA0\x80\xED\xBF\xBF\xED\xAF\x41", "\\ufffd" "\\ufffd" "\\ufffd" "\\ufffd" "\\ufffd" "\\ufffd" "\\ufffd" "\\ufffd" "\x41");
            test("\xF4\x91\x92\x93\xFF\x41\x80\xBF\x42", "\\ufffd" "\\ufffd" "\\ufffd" "\\ufffd" "\\ufffd" "\x41" "\\ufffd""\\ufffd" "\x42");
            test("\xE1\x80\xE2\xF0\x91\x92\xF1\xBF\x41", "\\ufffd" "\\ufffd" "\\ufffd" "\\ufffd" "\x41");
        }
    }

    SECTION("to_string")
    {
        auto test = [&](std::string const & input, std::string const & expected)
        {
            using std::to_string;
            const json j = input;
            CHECK(to_string(j) == "\"" + expected + "\"");
        };

        test(R"({"x":5,"y":6})", R"({\"x\":5,\"y\":6})");
        test("{\"x\":[10,null,null,null]}", R"({\"x\":[10,null,null,null]})");
        test("test", "test");
        test("[3,\"false\",false]", R"([3,\"false\",false])");
    }
}

TEST_CASE_TEMPLATE("serialization for extreme integer values", T, int32_t, uint32_t, int64_t, uint64_t) // NOLINT(readability-math-missing-parentheses, bugprone-throwing-static-initialization)
{
    SECTION("minimum")
    {
        constexpr auto minimum = (std::numeric_limits<T>::min)();
        const json j = minimum;
        CHECK(j.dump() == std::to_string(minimum));
    }

    SECTION("maximum")
    {
        constexpr auto maximum = (std::numeric_limits<T>::max)();
        const json j = maximum;
        CHECK(j.dump() == std::to_string(maximum));
    }
}

TEST_CASE("dump with binary values")
{
    auto binary = json::binary({1, 2, 3, 4});
    auto binary_empty = json::binary({});
    auto binary_with_subtype = json::binary({1, 2, 3, 4}, 128);
    auto binary_empty_with_subtype = json::binary({}, 128);

    const json object = {{"key", binary}};
    const json object_empty = {{"key", binary_empty}};
    const json object_with_subtype = {{"key", binary_with_subtype}};
    const json object_empty_with_subtype = {{"key", binary_empty_with_subtype}};

    const json array = {"value", 1, binary};
    const json array_empty = {"value", 1, binary_empty};
    const json array_with_subtype = {"value", 1, binary_with_subtype};
    const json array_empty_with_subtype = {"value", 1, binary_empty_with_subtype};

    SECTION("normal")
    {
        CHECK(binary.dump() == "{\"bytes\":[1,2,3,4],\"subtype\":null}");
        CHECK(binary_empty.dump() == "{\"bytes\":[],\"subtype\":null}");
        CHECK(binary_with_subtype.dump() == "{\"bytes\":[1,2,3,4],\"subtype\":128}");
        CHECK(binary_empty_with_subtype.dump() == "{\"bytes\":[],\"subtype\":128}");

        CHECK(object.dump() == "{\"key\":{\"bytes\":[1,2,3,4],\"subtype\":null}}");
        CHECK(object_empty.dump() == "{\"key\":{\"bytes\":[],\"subtype\":null}}");
        CHECK(object_with_subtype.dump() == "{\"key\":{\"bytes\":[1,2,3,4],\"subtype\":128}}");
        CHECK(object_empty_with_subtype.dump() == "{\"key\":{\"bytes\":[],\"subtype\":128}}");

        CHECK(array.dump() == "[\"value\",1,{\"bytes\":[1,2,3,4],\"subtype\":null}]");
        CHECK(array_empty.dump() == "[\"value\",1,{\"bytes\":[],\"subtype\":null}]");
        CHECK(array_with_subtype.dump() == "[\"value\",1,{\"bytes\":[1,2,3,4],\"subtype\":128}]");
        CHECK(array_empty_with_subtype.dump() == "[\"value\",1,{\"bytes\":[],\"subtype\":128}]");
    }

    SECTION("pretty-printed")
    {
        CHECK(binary.dump(4) == "{\n"
              "    \"bytes\": [1, 2, 3, 4],\n"
              "    \"subtype\": null\n"
              "}");
        CHECK(binary_empty.dump(4) == "{\n"
              "    \"bytes\": [],\n"
              "    \"subtype\": null\n"
              "}");
        CHECK(binary_with_subtype.dump(4) == "{\n"
              "    \"bytes\": [1, 2, 3, 4],\n"
              "    \"subtype\": 128\n"
              "}");
        CHECK(binary_empty_with_subtype.dump(4) == "{\n"
              "    \"bytes\": [],\n"
              "    \"subtype\": 128\n"
              "}");

        CHECK(object.dump(4) == "{\n"
              "    \"key\": {\n"
              "        \"bytes\": [1, 2, 3, 4],\n"
              "        \"subtype\": null\n"
              "    }\n"
              "}");
        CHECK(object_empty.dump(4) == "{\n"
              "    \"key\": {\n"
              "        \"bytes\": [],\n"
              "        \"subtype\": null\n"
              "    }\n"
              "}");
        CHECK(object_with_subtype.dump(4) == "{\n"
              "    \"key\": {\n"
              "        \"bytes\": [1, 2, 3, 4],\n"
              "        \"subtype\": 128\n"
              "    }\n"
              "}");
        CHECK(object_empty_with_subtype.dump(4) == "{\n"
              "    \"key\": {\n"
              "        \"bytes\": [],\n"
              "        \"subtype\": 128\n"
              "    }\n"
              "}");

        CHECK(array.dump(4) == "[\n"
              "    \"value\",\n"
              "    1,\n"
              "    {\n"
              "        \"bytes\": [1, 2, 3, 4],\n"
              "        \"subtype\": null\n"
              "    }\n"
              "]");
        CHECK(array_empty.dump(4) == "[\n"
              "    \"value\",\n"
              "    1,\n"
              "    {\n"
              "        \"bytes\": [],\n"
              "        \"subtype\": null\n"
              "    }\n"
              "]");
        CHECK(array_with_subtype.dump(4) == "[\n"
              "    \"value\",\n"
              "    1,\n"
              "    {\n"
              "        \"bytes\": [1, 2, 3, 4],\n"
              "        \"subtype\": 128\n"
              "    }\n"
              "]");
        CHECK(array_empty_with_subtype.dump(4) == "[\n"
              "    \"value\",\n"
              "    1,\n"
              "    {\n"
              "        \"bytes\": [],\n"
              "        \"subtype\": 128\n"
              "    }\n"
              "]");
    }
}

TEST_CASE("dump for basic_json with long double number_float_t")
{
    // Custom basic_json instantiation with long double as NumberFloatType.
    // On platforms where long double is wider than double (e.g. GCC/Clang on
    // Linux/macOS x86_64), dump() goes through the snprintf path in
    // serializer::dump_float(x, std::false_type). That branch must use the
    // "%.*Lg" format specifier; using "%.*g" with a long double argument is
    // undefined behavior and corrupts the output.
    using long_double_json = nlohmann::basic_json<std::map, std::vector, std::string,
          bool, std::int64_t, std::uint64_t, long double>;

    SECTION("round-trip dump/parse")
    {
        constexpr std::array<long double, 13> values =
        {
            {
                0.0L, -0.0L, 1.0L, -1.0L,
                0.5L, -0.5L, 1.5L, -2.25L,
                1.23e45L, 1.23e-45L,
                (std::numeric_limits<long double>::min)(),
                std::numeric_limits<long double>::lowest(),
                (std::numeric_limits<long double>::max)()
            }
        };

        for (long double v : values)
        {
            const long_double_json j = v;
            const auto s = j.dump();
            const auto j2 = long_double_json::parse(s);
            CHECK(j2.template get<long double>() == v);
        }
    }

    SECTION("exact dump string for simple values")
    {
        CHECK(long_double_json(0.5L).dump()   == "0.5");
        CHECK(long_double_json(-0.5L).dump()  == "-0.5");
        CHECK(long_double_json(1.5L).dump()   == "1.5");
        CHECK(long_double_json(-2.25L).dump() == "-2.25");
        CHECK(long_double_json(0.0L).dump()   == "0.0");
        CHECK(long_double_json(1.0L).dump()   == "1.0");
        CHECK(long_double_json(-1.0L).dump()  == "-1.0");
        CHECK(long_double_json(100.0L).dump() == "100.0");
    }

    SECTION("NaN and infinity dump as null")
    {
        CHECK(long_double_json(std::numeric_limits<long double>::quiet_NaN()).dump() == "null");

        // Probe the platform's runtime behavior — `volatile` forces a runtime
        // call rather than constexpr-folding to a known answer at compile time.
        // Skip the infinity assertions if std::isfinite() doesn't actually
        // recognize long double infinity on this platform (notably, Valgrind
        // 3.22's x87 80-bit emulation reports +/-inf as a large finite value).
        // TODO(rusloker): remove this guard once Valgrind's 80-bit long double
        // support ships (Valgrind bug https://bugs.kde.org/show_bug.cgi?id=197915,
        // ASSIGNED since 2009 — the Valgrind project tracks its bugs on
        // bugs.kde.org) and the minimum supported Valgrind version contains it.
        const volatile long double inf_probe = std::numeric_limits<long double>::infinity();
        if (!std::isfinite(inf_probe))
        {
            CHECK(long_double_json(std::numeric_limits<long double>::infinity()).dump() == "null");
            CHECK(long_double_json(-std::numeric_limits<long double>::infinity()).dump() == "null");
        }
    }

    SECTION("dump output matches double for exactly-representable values")
    {
        auto check_same = [](long double v_ld, double v_d)
        {
            const long_double_json j_ld = v_ld;
            const json j_d = v_d;
            CHECK(j_ld.dump() == j_d.dump());
        };

        check_same(0.0L,    0.0);
        check_same(0.5L,    0.5);
        check_same(-0.5L,  -0.5);
        check_same(1.5L,    1.5);
        check_same(-2.25L, -2.25);
        check_same(1.0L,    1.0);
        check_same(100.0L,  100.0);
    }
}