//     __ _____ _____ _____
//  __|  |   __|     |   | |  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"

// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
// line *before* including json.hpp, since the library #undefs it once the header
// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
// tests of deprecated functions are skipped if these functions are deleted
#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
#endif

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

#include <iostream>
#include <fstream>
#include <set>
#include "make_test_data_available.hpp"
#include "round_trip_corpus.hpp"
#include "test_utils.hpp"
#include "sax_countdown.hpp"
using utils::SaxCountdown;


TEST_CASE("UBJSON")
{
    SECTION("individual values")
    {
        SECTION("discarded")
        {
            // a discarded value cannot be serialized to UBJSON
            json const j = json::value_t::discarded;
            CHECK_THROWS_WITH_AS(json::to_ubjson(j), "[json.exception.type_error.321] cannot serialize discarded value to UBJSON", json::type_error&);
        }

        SECTION("discarded values nested in a container")
        {
            json const discarded = json::value_t::discarded;

            SECTION("in an array")
            {
                json const j = {1, discarded, 2};
#if JSON_DIAGNOSTICS
                CHECK_THROWS_WITH_AS(json::to_ubjson(j), "[json.exception.type_error.321] (/1) cannot serialize discarded value to UBJSON", json::type_error&);
#else
                CHECK_THROWS_WITH_AS(json::to_ubjson(j), "[json.exception.type_error.321] cannot serialize discarded value to UBJSON", json::type_error&);
#endif
            }

            SECTION("as an object value")
            {
                json j;
                j["a"] = 1;
                j["b"] = discarded;
#if JSON_DIAGNOSTICS
                CHECK_THROWS_WITH_AS(json::to_ubjson(j), "[json.exception.type_error.321] (/b) cannot serialize discarded value to UBJSON", json::type_error&);
#else
                CHECK_THROWS_WITH_AS(json::to_ubjson(j), "[json.exception.type_error.321] cannot serialize discarded value to UBJSON", json::type_error&);
#endif
            }

            SECTION("nested deeper (array in object in array)")
            {
                json inner_array = {1, discarded};
                json middle_object;
                middle_object["x"] = inner_array;
                json const j = {middle_object};
#if JSON_DIAGNOSTICS
                CHECK_THROWS_WITH_AS(json::to_ubjson(j), "[json.exception.type_error.321] (/0/x/1) cannot serialize discarded value to UBJSON", json::type_error&);
#else
                CHECK_THROWS_WITH_AS(json::to_ubjson(j), "[json.exception.type_error.321] cannot serialize discarded value to UBJSON", json::type_error&);
#endif
            }

            SECTION("optimized array of all-discarded elements")
            {
                json const j = {discarded, discarded};
#if JSON_DIAGNOSTICS
                CHECK_THROWS_WITH_AS(json::to_ubjson(j, true, true), "[json.exception.type_error.321] (/0) cannot serialize discarded value to UBJSON", json::type_error&);
#else
                CHECK_THROWS_WITH_AS(json::to_ubjson(j, true, true), "[json.exception.type_error.321] cannot serialize discarded value to UBJSON", json::type_error&);
#endif
            }
        }

        SECTION("null")
        {
            json const j = nullptr;
            std::vector<uint8_t> expected = {'Z'};
            const auto result = json::to_ubjson(j);
            CHECK(result == expected);

            // roundtrip
            CHECK(json::from_ubjson(result) == j);
            CHECK(json::from_ubjson(result, true, false) == j);
        }

        SECTION("boolean")
        {
            SECTION("true")
            {
                json const j = true;
                std::vector<uint8_t> const expected = {'T'};
                const auto result = json::to_ubjson(j);
                CHECK(result == expected);

                // roundtrip
                CHECK(json::from_ubjson(result) == j);
                CHECK(json::from_ubjson(result, true, false) == j);
            }

            SECTION("false")
            {
                json const j = false;
                std::vector<uint8_t> const expected = {'F'};
                const auto result = json::to_ubjson(j);
                CHECK(result == expected);

                // roundtrip
                CHECK(json::from_ubjson(result) == j);
                CHECK(json::from_ubjson(result, true, false) == j);
            }
        }

        SECTION("number")
        {
            SECTION("signed")
            {
                SECTION("-9223372036854775808..-2147483649 (int64)")
                {
                    std::vector<int64_t> const numbers
                    {
                        (std::numeric_limits<int64_t>::min)(),
                        -1000000000000000000LL,
                        -100000000000000000LL,
                        -10000000000000000LL,
                        -1000000000000000LL,
                        -100000000000000LL,
                        -10000000000000LL,
                        -1000000000000LL,
                        -100000000000LL,
                        -10000000000LL,
                        -2147483649LL,
                    };
                    for (auto i : numbers)
                    {
                        CAPTURE(i)

                        // create JSON value with integer number
                        json const j = i;

                        // check type
                        CHECK(j.is_number_integer());

                        // create expected byte vector
                        std::vector<uint8_t> const expected
                        {
                            static_cast<uint8_t>('L'),
                            static_cast<uint8_t>((i >> 56) & 0xff),
                            static_cast<uint8_t>((i >> 48) & 0xff),
                            static_cast<uint8_t>((i >> 40) & 0xff),
                            static_cast<uint8_t>((i >> 32) & 0xff),
                            static_cast<uint8_t>((i >> 24) & 0xff),
                            static_cast<uint8_t>((i >> 16) & 0xff),
                            static_cast<uint8_t>((i >> 8) & 0xff),
                            static_cast<uint8_t>(i & 0xff),
                        };

                        // compare result + size
                        const auto result = json::to_ubjson(j);
                        CHECK(result == expected);
                        CHECK(result.size() == 9);

                        // check individual bytes
                        CHECK(result[0] == 'L');
                        int64_t const restored = (static_cast<int64_t>(result[1]) << 070) +
                                                 (static_cast<int64_t>(result[2]) << 060) +
                                                 (static_cast<int64_t>(result[3]) << 050) +
                                                 (static_cast<int64_t>(result[4]) << 040) +
                                                 (static_cast<int64_t>(result[5]) << 030) +
                                                 (static_cast<int64_t>(result[6]) << 020) +
                                                 (static_cast<int64_t>(result[7]) << 010) +
                                                 static_cast<int64_t>(result[8]);
                        CHECK(restored == i);

                        // roundtrip
                        CHECK(json::from_ubjson(result) == j);
                        CHECK(json::from_ubjson(result, true, false) == j);
                    }
                }

                SECTION("-2147483648..-32769 (int32)")
                {
                    std::vector<int32_t> numbers;
                    numbers.push_back(-32769);
                    numbers.push_back(-100000);
                    numbers.push_back(-1000000);
                    numbers.push_back(-10000000);
                    numbers.push_back(-100000000);
                    numbers.push_back(-1000000000);
                    numbers.push_back(-2147483647 - 1); // https://stackoverflow.com/a/29356002/266378
                    for (auto i : numbers)
                    {
                        CAPTURE(i)

                        // create JSON value with integer number
                        json const j = i;

                        // check type
                        CHECK(j.is_number_integer());

                        // create expected byte vector
                        std::vector<uint8_t> const expected
                        {
                            static_cast<uint8_t>('l'),
                            static_cast<uint8_t>((i >> 24) & 0xff),
                            static_cast<uint8_t>((i >> 16) & 0xff),
                            static_cast<uint8_t>((i >> 8) & 0xff),
                            static_cast<uint8_t>(i & 0xff),
                        };

                        // compare result + size
                        const auto result = json::to_ubjson(j);
                        CHECK(result == expected);
                        CHECK(result.size() == 5);

                        // check individual bytes
                        CHECK(result[0] == 'l');
                        int32_t const restored = (static_cast<int32_t>(result[1]) << 030) +
                                                 (static_cast<int32_t>(result[2]) << 020) +
                                                 (static_cast<int32_t>(result[3]) << 010) +
                                                 static_cast<int32_t>(result[4]);
                        CHECK(restored == i);

                        // roundtrip
                        CHECK(json::from_ubjson(result) == j);
                        CHECK(json::from_ubjson(result, true, false) == j);
                    }
                }

                SECTION("-32768..-129 (int16)")
                {
                    for (int32_t i = -32768; i <= -129; i = utils::next_integer_sample(i, -129, 7))
                    {
                        CAPTURE(i)

                        // create JSON value with integer number
                        json const j = i;

                        // check type
                        CHECK(j.is_number_integer());

                        // create expected byte vector
                        std::vector<uint8_t> const expected
                        {
                            static_cast<uint8_t>('I'),
                            static_cast<uint8_t>((i >> 8) & 0xff),
                            static_cast<uint8_t>(i & 0xff),
                        };

                        // compare result + size
                        const auto result = json::to_ubjson(j);
                        CHECK(result == expected);
                        CHECK(result.size() == 3);

                        // check individual bytes
                        CHECK(result[0] == 'I');
                        auto const restored = static_cast<int16_t>(((result[1] << 8) + result[2]));
                        CHECK(restored == i);

                        // roundtrip
                        CHECK(json::from_ubjson(result) == j);
                        CHECK(json::from_ubjson(result, true, false) == j);
                    }
                }

                SECTION("-9263 (int16)")
                {
                    json const j = -9263;
                    std::vector<uint8_t> expected = {'I', 0xdb, 0xd1};

                    // compare result + size
                    const auto result = json::to_ubjson(j);
                    CHECK(result == expected);
                    CHECK(result.size() == 3);

                    // check individual bytes
                    CHECK(result[0] == 'I');
                    auto const restored = static_cast<int16_t>(((result[1] << 8) + result[2]));
                    CHECK(restored == -9263);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }

                SECTION("-128..-1 (int8)")
                {
                    for (auto i = -128; i <= -1; ++i)
                    {
                        CAPTURE(i)

                        // create JSON value with integer number
                        json const j = i;

                        // check type
                        CHECK(j.is_number_integer());

                        // create expected byte vector
                        std::vector<uint8_t> const expected
                        {
                            'i',
                            static_cast<uint8_t>(i),
                        };

                        // compare result + size
                        const auto result = json::to_ubjson(j);
                        CHECK(result == expected);
                        CHECK(result.size() == 2);

                        // check individual bytes
                        CHECK(result[0] == 'i');
                        CHECK(static_cast<int8_t>(result[1]) == i);

                        // roundtrip
                        CHECK(json::from_ubjson(result) == j);
                        CHECK(json::from_ubjson(result, true, false) == j);
                    }
                }

                SECTION("0..127 (int8)")
                {
                    for (size_t i = 0; i <= 127; ++i)
                    {
                        CAPTURE(i)

                        // create JSON value with integer number
                        json j = -1;
                        j.get_ref<json::number_integer_t&>() = static_cast<json::number_integer_t>(i);

                        // check type
                        CHECK(j.is_number_integer());

                        // create expected byte vector
                        std::vector<uint8_t> const expected
                        {
                            static_cast<uint8_t>('i'),
                            static_cast<uint8_t>(i),
                        };

                        // compare result + size
                        const auto result = json::to_ubjson(j);
                        CHECK(result == expected);
                        CHECK(result.size() == 2);

                        // check individual bytes
                        CHECK(result[0] == 'i');
                        CHECK(result[1] == i);

                        // roundtrip
                        CHECK(json::from_ubjson(result) == j);
                        CHECK(json::from_ubjson(result, true, false) == j);
                    }
                }

                SECTION("128..255 (uint8)")
                {
                    for (size_t i = 128; i <= 255; ++i)
                    {
                        CAPTURE(i)

                        // create JSON value with integer number
                        json j = -1;
                        j.get_ref<json::number_integer_t&>() = static_cast<json::number_integer_t>(i);

                        // check type
                        CHECK(j.is_number_integer());

                        // create expected byte vector
                        std::vector<uint8_t> const expected
                        {
                            static_cast<uint8_t>('U'),
                            static_cast<uint8_t>(i),
                        };

                        // compare result + size
                        const auto result = json::to_ubjson(j);
                        CHECK(result == expected);
                        CHECK(result.size() == 2);

                        // check individual bytes
                        CHECK(result[0] == 'U');
                        CHECK(result[1] == i);

                        // roundtrip
                        CHECK(json::from_ubjson(result) == j);
                        CHECK(json::from_ubjson(result, true, false) == j);
                    }
                }

                SECTION("256..32767 (int16)")
                {
                    for (size_t i = 256; i <= 32767; i = utils::next_integer_sample(i, static_cast<size_t>(32767), static_cast<size_t>(7)))
                    {
                        CAPTURE(i)

                        // create JSON value with integer number
                        json j = -1;
                        j.get_ref<json::number_integer_t&>() = static_cast<json::number_integer_t>(i);

                        // check type
                        CHECK(j.is_number_integer());

                        // create expected byte vector
                        std::vector<uint8_t> const expected
                        {
                            static_cast<uint8_t>('I'),
                            static_cast<uint8_t>((i >> 8) & 0xff),
                            static_cast<uint8_t>(i & 0xff),
                        };

                        // compare result + size
                        const auto result = json::to_ubjson(j);
                        CHECK(result == expected);
                        CHECK(result.size() == 3);

                        // check individual bytes
                        CHECK(result[0] == 'I');
                        auto const restored = static_cast<uint16_t>((static_cast<uint8_t>(result[1]) * 256) + static_cast<uint8_t>(result[2]));
                        CHECK(restored == i);

                        // roundtrip
                        CHECK(json::from_ubjson(result) == j);
                        CHECK(json::from_ubjson(result, true, false) == j);
                    }
                }

                SECTION("65536..2147483647 (int32)")
                {
                    for (uint32_t i :
                            {
                                65536u, 77777u, 1048576u
                            })
                    {
                        CAPTURE(i)

                        // create JSON value with integer number
                        json j = -1;
                        j.get_ref<json::number_integer_t&>() = static_cast<json::number_integer_t>(i);

                        // check type
                        CHECK(j.is_number_integer());

                        // create expected byte vector
                        std::vector<uint8_t> const expected
                        {
                            'l',
                            static_cast<uint8_t>((i >> 24) & 0xff),
                            static_cast<uint8_t>((i >> 16) & 0xff),
                            static_cast<uint8_t>((i >> 8) & 0xff),
                            static_cast<uint8_t>(i & 0xff),
                        };

                        // compare result + size
                        const auto result = json::to_ubjson(j);
                        CHECK(result == expected);
                        CHECK(result.size() == 5);

                        // check individual bytes
                        CHECK(result[0] == 'l');
                        uint32_t const restored = (static_cast<uint32_t>(result[1]) << 030) +
                                                  (static_cast<uint32_t>(result[2]) << 020) +
                                                  (static_cast<uint32_t>(result[3]) << 010) +
                                                  static_cast<uint32_t>(result[4]);
                        CHECK(restored == i);

                        // roundtrip
                        CHECK(json::from_ubjson(result) == j);
                        CHECK(json::from_ubjson(result, true, false) == j);
                    }
                }

                SECTION("2147483648..9223372036854775807 (int64)")
                {
                    std::vector<uint64_t> const v = {2147483648ul, 9223372036854775807ul};
                    for (uint64_t i : v)
                    {
                        CAPTURE(i)

                        // create JSON value with integer number
                        json j = -1;
                        j.get_ref<json::number_integer_t&>() = static_cast<json::number_integer_t>(i);

                        // check type
                        CHECK(j.is_number_integer());

                        // create expected byte vector
                        std::vector<uint8_t> const expected
                        {
                            'L',
                            static_cast<uint8_t>((i >> 070) & 0xff),
                            static_cast<uint8_t>((i >> 060) & 0xff),
                            static_cast<uint8_t>((i >> 050) & 0xff),
                            static_cast<uint8_t>((i >> 040) & 0xff),
                            static_cast<uint8_t>((i >> 030) & 0xff),
                            static_cast<uint8_t>((i >> 020) & 0xff),
                            static_cast<uint8_t>((i >> 010) & 0xff),
                            static_cast<uint8_t>(i & 0xff),
                        };

                        // compare result + size
                        const auto result = json::to_ubjson(j);
                        CHECK(result == expected);
                        CHECK(result.size() == 9);

                        // check individual bytes
                        CHECK(result[0] == 'L');
                        uint64_t const restored = (static_cast<uint64_t>(result[1]) << 070) +
                                                  (static_cast<uint64_t>(result[2]) << 060) +
                                                  (static_cast<uint64_t>(result[3]) << 050) +
                                                  (static_cast<uint64_t>(result[4]) << 040) +
                                                  (static_cast<uint64_t>(result[5]) << 030) +
                                                  (static_cast<uint64_t>(result[6]) << 020) +
                                                  (static_cast<uint64_t>(result[7]) << 010) +
                                                  static_cast<uint64_t>(result[8]);
                        CHECK(restored == i);

                        // roundtrip
                        CHECK(json::from_ubjson(result) == j);
                        CHECK(json::from_ubjson(result, true, false) == j);
                    }
                }
            }

            SECTION("unsigned")
            {
                SECTION("0..127 (int8)")
                {
                    for (size_t i = 0; i <= 127; ++i)
                    {
                        CAPTURE(i)

                        // create JSON value with unsigned integer number
                        json const j = i;

                        // check type
                        CHECK(j.is_number_unsigned());

                        // create expected byte vector
                        std::vector<uint8_t> const expected
                        {
                            'i',
                            static_cast<uint8_t>(i),
                        };

                        // compare result + size
                        const auto result = json::to_ubjson(j);
                        CHECK(result == expected);
                        CHECK(result.size() == 2);

                        // check individual bytes
                        CHECK(result[0] == 'i');
                        auto const restored = static_cast<uint8_t>(result[1]);
                        CHECK(restored == i);

                        // roundtrip
                        CHECK(json::from_ubjson(result) == j);
                        CHECK(json::from_ubjson(result, true, false) == j);
                    }
                }

                SECTION("128..255 (uint8)")
                {
                    for (size_t i = 128; i <= 255; ++i)
                    {
                        CAPTURE(i)

                        // create JSON value with unsigned integer number
                        json const j = i;

                        // check type
                        CHECK(j.is_number_unsigned());

                        // create expected byte vector
                        std::vector<uint8_t> const expected
                        {
                            'U',
                            static_cast<uint8_t>(i),
                        };

                        // compare result + size
                        const auto result = json::to_ubjson(j);
                        CHECK(result == expected);
                        CHECK(result.size() == 2);

                        // check individual bytes
                        CHECK(result[0] == 'U');
                        auto const restored = static_cast<uint8_t>(result[1]);
                        CHECK(restored == i);

                        // roundtrip
                        CHECK(json::from_ubjson(result) == j);
                        CHECK(json::from_ubjson(result, true, false) == j);
                    }
                }

                SECTION("256..32767 (int16)")
                {
                    for (size_t i = 256; i <= 32767; i = utils::next_integer_sample(i, static_cast<size_t>(32767), static_cast<size_t>(7)))
                    {
                        CAPTURE(i)

                        // create JSON value with unsigned integer number
                        json const j = i;

                        // check type
                        CHECK(j.is_number_unsigned());

                        // create expected byte vector
                        std::vector<uint8_t> const expected
                        {
                            'I',
                            static_cast<uint8_t>((i >> 8) & 0xff),
                            static_cast<uint8_t>(i & 0xff),
                        };

                        // compare result + size
                        const auto result = json::to_ubjson(j);
                        CHECK(result == expected);
                        CHECK(result.size() == 3);

                        // check individual bytes
                        CHECK(result[0] == 'I');
                        auto const restored = static_cast<uint16_t>((static_cast<uint8_t>(result[1]) * 256) + static_cast<uint8_t>(result[2]));
                        CHECK(restored == i);

                        // roundtrip
                        CHECK(json::from_ubjson(result) == j);
                        CHECK(json::from_ubjson(result, true, false) == j);
                    }
                }

                SECTION("65536..2147483647 (int32)")
                {
                    for (uint32_t i :
                            {
                                65536u, 77777u, 1048576u
                            })
                    {
                        CAPTURE(i)

                        // create JSON value with unsigned integer number
                        json const j = i;

                        // check type
                        CHECK(j.is_number_unsigned());

                        // create expected byte vector
                        std::vector<uint8_t> const expected
                        {
                            'l',
                            static_cast<uint8_t>((i >> 24) & 0xff),
                            static_cast<uint8_t>((i >> 16) & 0xff),
                            static_cast<uint8_t>((i >> 8) & 0xff),
                            static_cast<uint8_t>(i & 0xff),
                        };

                        // compare result + size
                        const auto result = json::to_ubjson(j);
                        CHECK(result == expected);
                        CHECK(result.size() == 5);

                        // check individual bytes
                        CHECK(result[0] == 'l');
                        uint32_t const restored = (static_cast<uint32_t>(result[1]) << 030) +
                                                  (static_cast<uint32_t>(result[2]) << 020) +
                                                  (static_cast<uint32_t>(result[3]) << 010) +
                                                  static_cast<uint32_t>(result[4]);
                        CHECK(restored == i);

                        // roundtrip
                        CHECK(json::from_ubjson(result) == j);
                        CHECK(json::from_ubjson(result, true, false) == j);
                    }
                }

                SECTION("2147483648..9223372036854775807 (int64)")
                {
                    std::vector<uint64_t> const v = {2147483648ul, 9223372036854775807ul};
                    for (uint64_t i : v)
                    {
                        CAPTURE(i)

                        // create JSON value with integer number
                        json const j = i;

                        // check type
                        CHECK(j.is_number_unsigned());

                        // create expected byte vector
                        std::vector<uint8_t> const expected
                        {
                            'L',
                            static_cast<uint8_t>((i >> 070) & 0xff),
                            static_cast<uint8_t>((i >> 060) & 0xff),
                            static_cast<uint8_t>((i >> 050) & 0xff),
                            static_cast<uint8_t>((i >> 040) & 0xff),
                            static_cast<uint8_t>((i >> 030) & 0xff),
                            static_cast<uint8_t>((i >> 020) & 0xff),
                            static_cast<uint8_t>((i >> 010) & 0xff),
                            static_cast<uint8_t>(i & 0xff),
                        };

                        // compare result + size
                        const auto result = json::to_ubjson(j);
                        CHECK(result == expected);
                        CHECK(result.size() == 9);

                        // check individual bytes
                        CHECK(result[0] == 'L');
                        uint64_t const restored = (static_cast<uint64_t>(result[1]) << 070) +
                                                  (static_cast<uint64_t>(result[2]) << 060) +
                                                  (static_cast<uint64_t>(result[3]) << 050) +
                                                  (static_cast<uint64_t>(result[4]) << 040) +
                                                  (static_cast<uint64_t>(result[5]) << 030) +
                                                  (static_cast<uint64_t>(result[6]) << 020) +
                                                  (static_cast<uint64_t>(result[7]) << 010) +
                                                  static_cast<uint64_t>(result[8]);
                        CHECK(restored == i);

                        // roundtrip
                        CHECK(json::from_ubjson(result) == j);
                        CHECK(json::from_ubjson(result, true, false) == j);
                    }
                }
            }

            SECTION("float64")
            {
                SECTION("3.1415925")
                {
                    double v = 3.1415925;
                    json const j = v;
                    std::vector<uint8_t> expected =
                    {
                        'D', 0x40, 0x09, 0x21, 0xfb, 0x3f, 0xa6, 0xde, 0xfc
                    };
                    const auto result = json::to_ubjson(j);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result) == v);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }
            }

            SECTION("high-precision number")
            {
                SECTION("unsigned integer number")
                {
                    std::vector<uint8_t> const vec = {'H', 'i', 0x14, '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0'};
                    const auto j = json::from_ubjson(vec);
                    CHECK(j.is_number_unsigned());
                    CHECK(j.dump() == "12345678901234567890");
                }

                SECTION("signed integer number")
                {
                    std::vector<uint8_t> const vec = {'H', 'i', 0x13, '-', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8'};
                    const auto j = json::from_ubjson(vec);
                    CHECK(j.is_number_integer());
                    CHECK(j.dump() == "-123456789012345678");
                }

                SECTION("floating-point number")
                {
                    std::vector<uint8_t> const vec = {'H', 'i', 0x16, '3', '.', '1', '4', '1', '5', '9',  '2', '6', '5', '3', '5', '8', '9',  '7', '9', '3', '2', '3', '8', '4',  '6'};
                    const auto j = json::from_ubjson(vec);
                    CHECK(j.is_number_float());
                    CHECK(j.dump() == "3.141592653589793");
                }

                SECTION("errors")
                {
                    // error while parsing length
                    std::vector<uint8_t> const vec0 = {'H', 'i'};
                    CHECK(json::from_ubjson(vec0, true, false).is_discarded());
                    // error while parsing string
                    std::vector<uint8_t> const vec1 = {'H', 'i', '1'};
                    CHECK(json::from_ubjson(vec1, true, false).is_discarded());

                    json _;
                    std::vector<uint8_t> const vec2 = {'H', 'i', 2, '1', 'A', '3'};
                    CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vec2), "[json.exception.parse_error.115] parse error at byte 5: syntax error while parsing UBJSON high-precision number: invalid number text: 1A", json::parse_error);
                    std::vector<uint8_t> const vec3 = {'H', 'i', 2, '1', '.'};
                    CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vec3), "[json.exception.parse_error.115] parse error at byte 5: syntax error while parsing UBJSON high-precision number: invalid number text: 1.", json::parse_error);
                    // Reject NULs where they are read, including trailing NULs and payloads cut off after one.
                    SECTION("NUL in high-precision number (issue #5753)")
                    {
                        for (const auto& vec : std::vector<std::vector<uint8_t>>
                    {
                        {'H', 'i', 3, '1', 0, 'x'},
                        {'H', 'i', 2, '1', 0},
                        {'H', 'i', 3, '1', 0}
                    })
                        {
                            CAPTURE(vec)
                            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vec), "[json.exception.parse_error.115] parse error at byte 5: syntax error while parsing UBJSON high-precision number: invalid number text; last byte: 0x00", json::parse_error);
                            CHECK(json::from_ubjson(vec, true, false).is_discarded());
                            CHECK(json::from_ubjson(vec, false, false).is_discarded());
                        }

                        std::vector<uint8_t> const nested = {'[', 'H', 'i', 3, '1', 0, 'x', ']'};
                        CHECK_THROWS_WITH_AS(_ = json::from_ubjson(nested), "[json.exception.parse_error.115] parse error at byte 6: syntax error while parsing UBJSON high-precision number: invalid number text; last byte: 0x00", json::parse_error);
                        CHECK(json::from_ubjson(nested, true, false).is_discarded());

                        std::vector<uint8_t> const valid = {'H', 'i', 1, '1'};
                        const auto j = json::from_ubjson(valid);
                        CHECK(j.is_number_unsigned());
                        CHECK(j == json(1));
                    }

                    std::vector<uint8_t> const vec_overflow = {'H', 'i', 5, '1', 'e', '4', '0', '0'};
                    CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vec_overflow), "[json.exception.out_of_range.406] number overflow parsing '1e400'", json::out_of_range&);
                    std::vector<uint8_t> const vec4 = {'H', 2, '1', '0'};
                    CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vec4), "[json.exception.parse_error.113] parse error at byte 2: syntax error while parsing UBJSON size: expected length type specification (U, i, I, l, L) after '#'; last byte: 0x02", json::parse_error);
                }

                SECTION("serialization")
                {
                    // number that does not fit int64
                    json const j = 11111111111111111111ULL;
                    CHECK(j.is_number_unsigned());

                    // number will be serialized to high-precision number
                    const auto vec = json::to_ubjson(j);
                    std::vector<uint8_t> expected = {'H', 'i', 0x14, '1',  '1',  '1',  '1',  '1', '1',  '1',  '1',  '1',  '1', '1',  '1',  '1',  '1',  '1', '1',  '1',  '1',  '1',  '1'};
                    CHECK(vec == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(vec) == j);
                }
            }
        }

        SECTION("string")
        {
            SECTION("N = 0..127")
            {
                for (size_t N = 0; N <= 127; ++N)
                {
                    CAPTURE(N)

                    // create JSON value with string containing of N * 'x'
                    const auto s = std::string(N, 'x');
                    json const j = s;

                    // create expected byte vector
                    std::vector<uint8_t> expected;
                    expected.push_back('S');
                    expected.push_back('i');
                    expected.push_back(static_cast<uint8_t>(N));
                    for (size_t i = 0; i < N; ++i)
                    {
                        expected.push_back('x');
                    }

                    // compare result + size
                    const auto result = json::to_ubjson(j);
                    CHECK(result == expected);
                    CHECK(result.size() == N + 3);
                    // check that no null byte is appended
                    if (N > 0)
                    {
                        CHECK(result.back() != '\x00');
                    }

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }
            }

            SECTION("N = 128..255")
            {
                for (size_t N = 128; N <= 255; ++N)
                {
                    CAPTURE(N)

                    // create JSON value with string containing of N * 'x'
                    const auto s = std::string(N, 'x');
                    json const j = s;

                    // create expected byte vector
                    std::vector<uint8_t> expected;
                    expected.push_back('S');
                    expected.push_back('U');
                    expected.push_back(static_cast<uint8_t>(N));
                    for (size_t i = 0; i < N; ++i)
                    {
                        expected.push_back('x');
                    }

                    // compare result + size
                    const auto result = json::to_ubjson(j);
                    CHECK(result == expected);
                    CHECK(result.size() == N + 3);
                    // check that no null byte is appended
                    CHECK(result.back() != '\x00');

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }
            }

            SECTION("N = 256..32767")
            {
                for (size_t N :
                        {
                            256u, 999u, 1025u, 3333u, 2048u, 32767u
                        })
                {
                    CAPTURE(N)

                    // create JSON value with string containing of N * 'x'
                    const auto s = std::string(N, 'x');
                    json const j = s;

                    // create expected byte vector (hack: create string first)
                    std::vector<uint8_t> expected(N, 'x');
                    // reverse order of commands, because we insert at begin()
                    expected.insert(expected.begin(), static_cast<uint8_t>(N & 0xff));
                    expected.insert(expected.begin(), static_cast<uint8_t>((N >> 8) & 0xff));
                    expected.insert(expected.begin(), 'I');
                    expected.insert(expected.begin(), 'S');

                    // compare result + size
                    const auto result = json::to_ubjson(j);
                    CHECK(result == expected);
                    CHECK(result.size() == N + 4);
                    // check that no null byte is appended
                    CHECK(result.back() != '\x00');

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }
            }

            SECTION("N = 65536..2147483647")
            {
                for (size_t N :
                        {
                            65536u, 77777u, 1048576u
                        })
                {
                    CAPTURE(N)

                    // create JSON value with string containing of N * 'x'
                    const auto s = std::string(N, 'x');
                    json const j = s;

                    // create expected byte vector (hack: create string first)
                    std::vector<uint8_t> expected(N, 'x');
                    // reverse order of commands, because we insert at begin()
                    expected.insert(expected.begin(), static_cast<uint8_t>(N & 0xff));
                    expected.insert(expected.begin(), static_cast<uint8_t>((N >> 8) & 0xff));
                    expected.insert(expected.begin(), static_cast<uint8_t>((N >> 16) & 0xff));
                    expected.insert(expected.begin(), static_cast<uint8_t>((N >> 24) & 0xff));
                    expected.insert(expected.begin(), 'l');
                    expected.insert(expected.begin(), 'S');

                    // compare result + size
                    const auto result = json::to_ubjson(j);
                    CHECK(result == expected);
                    CHECK(result.size() == N + 6);
                    // check that no null byte is appended
                    CHECK(result.back() != '\x00');

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }
            }
        }

        SECTION("binary")
        {
            SECTION("N = 0..127")
            {
                for (std::size_t N = 0; N <= 127; ++N)
                {
                    CAPTURE(N)

                    // create JSON value with byte array containing of N * 'x'
                    const auto s = std::vector<std::uint8_t>(N, 'x');
                    json const j = json::binary(s);

                    // create expected byte vector
                    std::vector<std::uint8_t> expected;
                    expected.push_back(static_cast<std::uint8_t>('['));
                    if (N != 0)
                    {
                        expected.push_back(static_cast<std::uint8_t>('$'));
                        expected.push_back(static_cast<std::uint8_t>('U'));
                    }
                    expected.push_back(static_cast<std::uint8_t>('#'));
                    expected.push_back(static_cast<std::uint8_t>('i'));
                    expected.push_back(static_cast<std::uint8_t>(N));
                    for (size_t i = 0; i < N; ++i)
                    {
                        expected.push_back(0x78);
                    }

                    // compare result + size
                    const auto result = json::to_ubjson(j, true, true);
                    CHECK(result == expected);
                    if (N == 0)
                    {
                        CHECK(result.size() == N + 4);
                    }
                    else
                    {
                        CHECK(result.size() == N + 6);
                    }

                    // check that no null byte is appended
                    if (N > 0)
                    {
                        CHECK(result.back() != '\x00');
                    }

                    // roundtrip only works to an array of numbers
                    json j_out = s;
                    CHECK(json::from_ubjson(result) == j_out);
                    CHECK(json::from_ubjson(result, true, false) == j_out);
                }
            }

            SECTION("N = 128..255")
            {
                for (std::size_t N = 128; N <= 255; ++N)
                {
                    CAPTURE(N)

                    // create JSON value with byte array containing of N * 'x'
                    const auto s = std::vector<std::uint8_t>(N, 'x');
                    json const j = json::binary(s);

                    // create expected byte vector
                    std::vector<uint8_t> expected;
                    expected.push_back(static_cast<std::uint8_t>('['));
                    expected.push_back(static_cast<std::uint8_t>('$'));
                    expected.push_back(static_cast<std::uint8_t>('U'));
                    expected.push_back(static_cast<std::uint8_t>('#'));
                    expected.push_back(static_cast<std::uint8_t>('U'));
                    expected.push_back(static_cast<std::uint8_t>(N));
                    for (size_t i = 0; i < N; ++i)
                    {
                        expected.push_back(0x78);
                    }

                    // compare result + size
                    const auto result = json::to_ubjson(j, true, true);
                    CHECK(result == expected);
                    CHECK(result.size() == N + 6);
                    // check that no null byte is appended
                    CHECK(result.back() != '\x00');

                    // roundtrip only works to an array of numbers
                    json j_out = s;
                    CHECK(json::from_ubjson(result) == j_out);
                    CHECK(json::from_ubjson(result, true, false) == j_out);
                }
            }

            SECTION("N = 256..32767")
            {
                for (std::size_t N :
                        {
                            256u, 999u, 1025u, 3333u, 2048u, 32767u
                        })
                {
                    CAPTURE(N)

                    // create JSON value with byte array containing of N * 'x'
                    const auto s = std::vector<std::uint8_t>(N, 'x');
                    json const j = json::binary(s);

                    // create expected byte vector
                    std::vector<std::uint8_t> expected(N + 7, 'x');
                    expected[0] = '[';
                    expected[1] = '$';
                    expected[2] = 'U';
                    expected[3] = '#';
                    expected[4] = 'I';
                    expected[5] = static_cast<std::uint8_t>((N >> 8) & 0xFF);
                    expected[6] = static_cast<std::uint8_t>(N & 0xFF);

                    // compare result + size
                    const auto result = json::to_ubjson(j, true, true);
                    CHECK(result == expected);
                    CHECK(result.size() == N + 7);
                    // check that no null byte is appended
                    CHECK(result.back() != '\x00');

                    // roundtrip only works to an array of numbers
                    json j_out = s;
                    CHECK(json::from_ubjson(result) == j_out);
                    CHECK(json::from_ubjson(result, true, false) == j_out);
                }
            }

            SECTION("N = 32768..2147483647")
            {
                for (std::size_t N :
                        {
                            32768u, 77777u, 1048576u
                        })
                {
                    CAPTURE(N)

                    // create JSON value with byte array containing of N * 'x'
                    const auto s = std::vector<std::uint8_t>(N, 'x');
                    json const j = json::binary(s);

                    // create expected byte vector
                    std::vector<std::uint8_t> expected(N + 9, 'x');
                    expected[0] = '[';
                    expected[1] = '$';
                    expected[2] = 'U';
                    expected[3] = '#';
                    expected[4] = 'l';
                    expected[5] = static_cast<std::uint8_t>((N >> 24) & 0xFF);
                    expected[6] = static_cast<std::uint8_t>((N >> 16) & 0xFF);
                    expected[7] = static_cast<std::uint8_t>((N >> 8) & 0xFF);
                    expected[8] = static_cast<std::uint8_t>(N & 0xFF);

                    // compare result + size
                    const auto result = json::to_ubjson(j, true, true);
                    CHECK(result == expected);
                    CHECK(result.size() == N + 9);
                    // check that no null byte is appended
                    CHECK(result.back() != '\x00');

                    // roundtrip only works to an array of numbers
                    json j_out = s;
                    CHECK(json::from_ubjson(result) == j_out);
                    CHECK(json::from_ubjson(result, true, false) == j_out);
                }
            }

            SECTION("Other Serializations")
            {
                const std::size_t N = 10;
                const auto s = std::vector<std::uint8_t>(N, 'x');
                json const j = json::binary(s);

                SECTION("No Count No Type")
                {
                    std::vector<uint8_t> expected;
                    expected.push_back(static_cast<std::uint8_t>('['));
                    for (std::size_t i = 0; i < N; ++i)
                    {
                        expected.push_back(static_cast<std::uint8_t>('U'));
                        expected.push_back(static_cast<std::uint8_t>(0x78));
                    }
                    expected.push_back(static_cast<std::uint8_t>(']'));

                    // compare result + size
                    const auto result = json::to_ubjson(j, false, false);
                    CHECK(result == expected);
                    CHECK(result.size() == N + 12);
                    // check that no null byte is appended
                    CHECK(result.back() != '\x00');

                    // roundtrip only works to an array of numbers
                    json j_out = s;
                    CHECK(json::from_ubjson(result) == j_out);
                    CHECK(json::from_ubjson(result, true, false) == j_out);
                }

                SECTION("Yes Count No Type")
                {
                    std::vector<std::uint8_t> expected;
                    expected.push_back(static_cast<std::uint8_t>('['));
                    expected.push_back(static_cast<std::uint8_t>('#'));
                    expected.push_back(static_cast<std::uint8_t>('i'));
                    expected.push_back(static_cast<std::uint8_t>(N));

                    for (size_t i = 0; i < N; ++i)
                    {
                        expected.push_back(static_cast<std::uint8_t>('U'));
                        expected.push_back(static_cast<std::uint8_t>(0x78));
                    }

                    // compare result + size
                    const auto result = json::to_ubjson(j, true, false);
                    CHECK(result == expected);
                    CHECK(result.size() == N + 14);
                    // check that no null byte is appended
                    CHECK(result.back() != '\x00');

                    // roundtrip only works to an array of numbers
                    json j_out = s;
                    CHECK(json::from_ubjson(result) == j_out);
                    CHECK(json::from_ubjson(result, true, false) == j_out);
                }
            }
        }

        SECTION("array")
        {
            SECTION("empty")
            {
                SECTION("size=false type=false")
                {
                    json const j = json::array();
                    std::vector<uint8_t> expected = {'[', ']'};
                    const auto result = json::to_ubjson(j);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }

                SECTION("size=true type=false")
                {
                    json const j = json::array();
                    std::vector<uint8_t> expected = {'[', '#', 'i', 0};
                    const auto result = json::to_ubjson(j, true);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }

                SECTION("size=true type=true")
                {
                    json const j = json::array();
                    std::vector<uint8_t> expected = {'[', '#', 'i', 0};
                    const auto result = json::to_ubjson(j, true, true);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }
            }

            SECTION("[null]")
            {
                SECTION("size=false type=false")
                {
                    json const j = {nullptr};
                    std::vector<uint8_t> expected = {'[', 'Z', ']'};
                    const auto result = json::to_ubjson(j);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }

                SECTION("size=true type=false")
                {
                    json const j = {nullptr};
                    std::vector<uint8_t> expected = {'[', '#', 'i', 1, 'Z'};
                    const auto result = json::to_ubjson(j, true);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }

                SECTION("size=true type=true")
                {
                    json const j = {nullptr};
                    std::vector<uint8_t> expected = {'[', '$', 'Z', '#', 'i', 1};
                    const auto result = json::to_ubjson(j, true, true);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }
            }

            SECTION("[1,2,3,4,5]")
            {
                SECTION("size=false type=false")
                {
                    json const j = json::parse("[1,2,3,4,5]");
                    std::vector<uint8_t> expected = {'[', 'i', 1, 'i', 2, 'i', 3, 'i', 4, 'i', 5, ']'};
                    const auto result = json::to_ubjson(j);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }

                SECTION("size=true type=false")
                {
                    json const j = json::parse("[1,2,3,4,5]");
                    std::vector<uint8_t> expected = {'[', '#', 'i', 5, 'i', 1, 'i', 2, 'i', 3, 'i', 4, 'i', 5};
                    const auto result = json::to_ubjson(j, true);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }

                SECTION("size=true type=true")
                {
                    json const j = json::parse("[1,2,3,4,5]");
                    std::vector<uint8_t> expected = {'[', '$', 'i', '#', 'i', 5, 1, 2, 3, 4, 5};
                    const auto result = json::to_ubjson(j, true, true);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }
            }

            SECTION("[[[[]]]]")
            {
                SECTION("size=false type=false")
                {
                    json const j = json::parse("[[[[]]]]");
                    std::vector<uint8_t> expected = {'[', '[', '[', '[', ']', ']', ']', ']'};
                    const auto result = json::to_ubjson(j);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }

                SECTION("size=true type=false")
                {
                    json const j = json::parse("[[[[]]]]");
                    std::vector<uint8_t> expected = {'[', '#', 'i', 1, '[', '#', 'i', 1, '[', '#', 'i', 1, '[', '#', 'i', 0};
                    const auto result = json::to_ubjson(j, true);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }

                SECTION("size=true type=true")
                {
                    json const j = json::parse("[[[[]]]]");
                    std::vector<uint8_t> expected = {'[', '$', '[', '#', 'i', 1, '$', '[', '#', 'i', 1, '$', '[', '#', 'i', 1, '#', 'i', 0};
                    const auto result = json::to_ubjson(j, true, true);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }
            }

            SECTION("array with uint16_t elements")
            {
                SECTION("size=false type=false")
                {
                    json j(257, nullptr);
                    std::vector<uint8_t> expected(j.size() + 2, 'Z'); // all null
                    expected[0] = '['; // opening array
                    expected[258] = ']'; // closing array
                    const auto result = json::to_ubjson(j);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }

                SECTION("size=true type=false")
                {
                    json j(257, nullptr);
                    std::vector<uint8_t> expected(j.size() + 5, 'Z'); // all null
                    expected[0] = '['; // opening array
                    expected[1] = '#'; // array size
                    expected[2] = 'I'; // int16
                    expected[3] = 0x01; // 0x0101, first byte
                    expected[4] = 0x01; // 0x0101, second byte
                    const auto result = json::to_ubjson(j, true);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }

                SECTION("size=true type=true")
                {
                    json j(257, nullptr);
                    std::vector<uint8_t> expected = {'[', '$', 'Z', '#', 'I', 0x01, 0x01};
                    const auto result = json::to_ubjson(j, true, true);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }
            }

            SECTION("array with uint32_t elements")
            {
                SECTION("size=false type=false")
                {
                    json j(65793, nullptr);
                    std::vector<uint8_t> expected(j.size() + 2, 'Z'); // all null
                    expected[0] = '['; // opening array
                    expected[65794] = ']'; // closing array
                    const auto result = json::to_ubjson(j);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }

                SECTION("size=true type=false")
                {
                    json j(65793, nullptr);
                    std::vector<uint8_t> expected(j.size() + 7, 'Z'); // all null
                    expected[0] = '['; // opening array
                    expected[1] = '#'; // array size
                    expected[2] = 'l'; // int32
                    expected[3] = 0x00; // 0x00010101, first byte
                    expected[4] = 0x01; // 0x00010101, second byte
                    expected[5] = 0x01; // 0x00010101, third byte
                    expected[6] = 0x01; // 0x00010101, fourth byte
                    const auto result = json::to_ubjson(j, true);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }

                SECTION("size=true type=true")
                {
                    json j(65793, nullptr);
                    std::vector<uint8_t> expected = {'[', '$', 'Z', '#', 'l', 0x00, 0x01, 0x01, 0x01};
                    const auto result = json::to_ubjson(j, true, true);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }
            }
        }

        SECTION("object")
        {
            SECTION("empty")
            {
                SECTION("size=false type=false")
                {
                    json const j = json::object();
                    std::vector<uint8_t> expected = {'{', '}'};
                    const auto result = json::to_ubjson(j);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }

                SECTION("size=true type=false")
                {
                    json const j = json::object();
                    std::vector<uint8_t> expected = {'{', '#', 'i', 0};
                    const auto result = json::to_ubjson(j, true);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }

                SECTION("size=true type=true")
                {
                    json const j = json::object();
                    std::vector<uint8_t> expected = {'{', '#', 'i', 0};
                    const auto result = json::to_ubjson(j, true, true);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }
            }

            SECTION("{\"\":null}")
            {
                SECTION("size=false type=false")
                {
                    json const j = {{"", nullptr}};
                    std::vector<uint8_t> expected = {'{', 'i', 0, 'Z', '}'};
                    const auto result = json::to_ubjson(j);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }

                SECTION("size=true type=false")
                {
                    json const j = {{"", nullptr}};
                    std::vector<uint8_t> expected = {'{', '#', 'i', 1, 'i', 0, 'Z'};
                    const auto result = json::to_ubjson(j, true);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }

                SECTION("size=true type=true")
                {
                    json const j = {{"", nullptr}};
                    std::vector<uint8_t> expected = {'{', '$', 'Z', '#', 'i', 1, 'i', 0};
                    const auto result = json::to_ubjson(j, true, true);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }
            }

            SECTION("{\"a\": {\"b\": {\"c\": {}}}}")
            {
                SECTION("size=false type=false")
                {
                    json const j = json::parse(R"({"a": {"b": {"c": {}}}})");
                    std::vector<uint8_t> expected =
                    {
                        '{', 'i', 1, 'a', '{', 'i', 1, 'b', '{', 'i', 1, 'c', '{', '}', '}', '}', '}'
                    };
                    const auto result = json::to_ubjson(j);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }

                SECTION("size=true type=false")
                {
                    json const j = json::parse(R"({"a": {"b": {"c": {}}}})");
                    std::vector<uint8_t> expected =
                    {
                        '{', '#', 'i', 1, 'i', 1, 'a', '{', '#', 'i', 1, 'i', 1, 'b', '{', '#', 'i', 1, 'i', 1, 'c', '{', '#', 'i', 0
                    };
                    const auto result = json::to_ubjson(j, true);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }

                SECTION("size=true type=true")
                {
                    json const j = json::parse(R"({"a": {"b": {"c": {}}}})");
                    std::vector<uint8_t> expected =
                    {
                        '{', '$', '{', '#', 'i', 1, 'i', 1, 'a', '$', '{', '#', 'i', 1, 'i', 1, 'b', '$', '{', '#', 'i', 1, 'i', 1, 'c', '#', 'i', 0
                    };
                    const auto result = json::to_ubjson(j, true, true);
                    CHECK(result == expected);

                    // roundtrip
                    CHECK(json::from_ubjson(result) == j);
                    CHECK(json::from_ubjson(result, true, false) == j);
                }
            }
        }
    }

    SECTION("errors")
    {
        SECTION("strict mode")
        {
            std::vector<uint8_t> const vec = {'Z', 'Z'};
            SECTION("non-strict mode")
            {
                const auto result = json::from_ubjson(vec, false);
                CHECK(result == json());
            }

            SECTION("strict mode")
            {
                json _;
                CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vec), "[json.exception.parse_error.110] parse error at byte 2: syntax error while parsing UBJSON value: expected end of input; last byte: 0x5A", json::parse_error&);
            }
        }

        SECTION("excessive size")
        {
            SECTION("array")
            {
                std::vector<uint8_t> const v_ubjson = {'[', '$', 'Z', '#', 'L', 0x78, 0x28, 0x00, 0x68, 0x28, 0x69, 0x69, 0x17};
                json _;
                CHECK_THROWS_AS(_ = json::from_ubjson(v_ubjson), json::out_of_range&);

                json j;
                nlohmann::detail::json_sax_dom_callback_parser<json, decltype(nlohmann::detail::input_adapter(v_ubjson))> scp(j, [](int /*unused*/, json::parse_event_t /*unused*/, const json& /*unused*/) noexcept
                {
                    return true;
                });
                CHECK_THROWS_AS(_ = json::sax_parse(v_ubjson, &scp, json::input_format_t::ubjson), json::out_of_range&);
            }

            SECTION("object")
            {
                std::vector<uint8_t> const v_ubjson = {'{', '$', 'Z', '#', 'L', 0x78, 0x28, 0x00, 0x68, 0x28, 0x69, 0x69, 0x17};
                json _;
                CHECK_THROWS_AS(_ = json::from_ubjson(v_ubjson), json::out_of_range&);

                json j;
                nlohmann::detail::json_sax_dom_callback_parser<json, decltype(nlohmann::detail::input_adapter(v_ubjson))> scp(j, [](int /*unused*/, json::parse_event_t /*unused*/, const json& /*unused*/) noexcept
                {
                    return true;
                });
                CHECK_THROWS_AS(_ = json::sax_parse(v_ubjson, &scp, json::input_format_t::ubjson), json::out_of_range&);
            }

            SECTION("array with a known size, read with a callback")
            {
                // a sized array announces its length to start_array()
                std::vector<uint8_t> const v_ubjson = {'[', '#', 'i', 2, 'i', 1, 'i', 2};
                json j;
                nlohmann::detail::json_sax_dom_callback_parser<json, decltype(nlohmann::detail::input_adapter(v_ubjson))> scp(j, [](int /*unused*/, json::parse_event_t /*unused*/, const json& /*unused*/) noexcept
                {
                    return true;
                });
                CHECK(json::sax_parse(v_ubjson, &scp, json::input_format_t::ubjson));
                CHECK(j == json({1, 2}));

                // the readers reject a size this large before they announce
                // it, so it can only reach start_array() directly (the largest
                // value stands for an unknown size and is never checked)
                json k;
                nlohmann::detail::json_sax_dom_callback_parser<json, decltype(nlohmann::detail::input_adapter(v_ubjson))> scp2(k, [](int /*unused*/, json::parse_event_t /*unused*/, const json& /*unused*/) noexcept
                {
                    return true;
                });
                CHECK_THROWS_AS(scp2.start_array((std::numeric_limits<std::size_t>::max)() - 1), json::out_of_range&);
            }
        }
    }

    SECTION("SAX aborts")
    {
        SECTION("start_array()")
        {
            std::vector<uint8_t> const v = {'[', 'T', 'F', ']'};
            SaxCountdown scp(0);
            CHECK(!json::sax_parse(v, &scp, json::input_format_t::ubjson));
        }

        SECTION("start_object()")
        {
            std::vector<uint8_t> const v = {'{', 'i', 3, 'f', 'o', 'o', 'F', '}'};
            SaxCountdown scp(0);
            CHECK(!json::sax_parse(v, &scp, json::input_format_t::ubjson));
        }

        SECTION("key() in object")
        {
            std::vector<uint8_t> const v = {'{', 'i', 3, 'f', 'o', 'o', 'F', '}'};
            SaxCountdown scp(1);
            CHECK(!json::sax_parse(v, &scp, json::input_format_t::ubjson));
        }

        SECTION("start_array(len)")
        {
            std::vector<uint8_t> const v = {'[', '#', 'i', '2', 'T', 'F'};
            SaxCountdown scp(0);
            CHECK(!json::sax_parse(v, &scp, json::input_format_t::ubjson));
        }

        SECTION("start_object(len)")
        {
            std::vector<uint8_t> const v = {'{', '#', 'i', '1', 3, 'f', 'o', 'o', 'F'};
            SaxCountdown scp(0);
            CHECK(!json::sax_parse(v, &scp, json::input_format_t::ubjson));
        }

        SECTION("key() in object with length")
        {
            std::vector<uint8_t> const v = {'{', 'i', 3, 'f', 'o', 'o', 'F', '}'};
            SaxCountdown scp(1);
            CHECK(!json::sax_parse(v, &scp, json::input_format_t::ubjson));
        }
    }

    SECTION("parsing values")
    {
        SECTION("strings")
        {
            // create a single-character string for all number types
            std::vector<uint8_t> s_i = {'S', 'i', 1, 'a'};
            std::vector<uint8_t> const s_U = {'S', 'U', 1, 'a'};
            std::vector<uint8_t> const s_I = {'S', 'I', 0, 1, 'a'};
            std::vector<uint8_t> const s_l = {'S', 'l', 0, 0, 0, 1, 'a'};
            std::vector<uint8_t> const s_L = {'S', 'L', 0, 0, 0, 0, 0, 0, 0, 1, 'a'};

            // check if string is parsed correctly to "a"
            CHECK(json::from_ubjson(s_i) == "a");
            CHECK(json::from_ubjson(s_U) == "a");
            CHECK(json::from_ubjson(s_I) == "a");
            CHECK(json::from_ubjson(s_l) == "a");
            CHECK(json::from_ubjson(s_L) == "a");

            // roundtrip: output should be optimized
            CHECK(json::to_ubjson(json::from_ubjson(s_i)) == s_i);
            CHECK(json::to_ubjson(json::from_ubjson(s_U)) == s_i);
            CHECK(json::to_ubjson(json::from_ubjson(s_I)) == s_i);
            CHECK(json::to_ubjson(json::from_ubjson(s_l)) == s_i);
            CHECK(json::to_ubjson(json::from_ubjson(s_L)) == s_i);
        }

        SECTION("no-op markers")
        {
            // A no-op ('N') is valid wherever a value may start; it is consumed
            // by get_ignore_noop() before the value is read. It is not valid
            // where a string length type specification is expected.

            SECTION("accepted where a value may start")
            {
                // at top level, also repeated
                CHECK(json::from_ubjson(std::vector<uint8_t>({'N', 'i', 1})) == json(1));
                CHECK(json::from_ubjson(std::vector<uint8_t>({'N', 'N', 'N', 'i', 1})) == json(1));

                // inside an array of unknown size, before and after an element
                CHECK(json::from_ubjson(std::vector<uint8_t>({'[', 'N', 'i', 1, ']'})) == json({1}));
                CHECK(json::from_ubjson(std::vector<uint8_t>({'[', 'i', 1, 'N', ']'})) == json({1}));

                // inside an object of unknown size: before a key, between key
                // and value, and before the closing '}'
                CHECK(json::from_ubjson(std::vector<uint8_t>({'{', 'N', 'U', 1, 'a', 'i', 1, '}'})) == json({{"a", 1}}));
                CHECK(json::from_ubjson(std::vector<uint8_t>({'{', 'U', 1, 'a', 'N', 'i', 1, '}'})) == json({{"a", 1}}));
                CHECK(json::from_ubjson(std::vector<uint8_t>({'{', 'U', 1, 'a', 'i', 1, 'N', '}'})) == json({{"a", 1}}));
            }

            SECTION("rejected where a length type specification is expected")
            {
                json _;

                // after the 'S' marker of a string value
                std::vector<uint8_t> const v_S = {'S', 'N', 'U', 1, 'a'};
                CHECK_THROWS_WITH_AS(_ = json::from_ubjson(v_S), "[json.exception.parse_error.113] parse error at byte 2: syntax error while parsing UBJSON string: expected length type specification (U, i, I, l, L); last byte: 0x4E", json::parse_error&);

                // as the key length of an object with a known size, where
                // no-ops are not permitted in the first place
                std::vector<uint8_t> const v_key = {'{', '#', 'i', 1, 'N', 'U', 1, 'a', 'i', 1};
                CHECK_THROWS_WITH_AS(_ = json::from_ubjson(v_key), "[json.exception.parse_error.113] parse error at byte 5: syntax error while parsing UBJSON string: expected length type specification (U, i, I, l, L); last byte: 0x4E", json::parse_error&);
            }
        }

        SECTION("number")
        {
            SECTION("float")
            {
                // float32
                std::vector<uint8_t> const v_d = {'d', 0x40, 0x49, 0x0f, 0xd0};
                CHECK(json::from_ubjson(v_d) == 3.14159f);

                // float64
                std::vector<uint8_t> const v_D = {'D', 0x40, 0x09, 0x21, 0xf9, 0xf0, 0x1b, 0x86, 0x6e};
                CHECK(json::from_ubjson(v_D) == 3.14159);

                // float32 is serialized as float64 as the library does not support float32
                CHECK(json::to_ubjson(json::from_ubjson(v_d)) == json::to_ubjson(3.14159f));
            }
        }

        SECTION("array")
        {
            SECTION("optimized version (length only)")
            {
                // create vector with two elements of the same type
                std::vector<uint8_t> const v_TU = {'[', '#', 'U', 2, 'T', 'T'};
                std::vector<uint8_t> const v_T = {'[', '#', 'i', 2, 'T', 'T'};
                std::vector<uint8_t> const v_F = {'[', '#', 'i', 2, 'F', 'F'};
                std::vector<uint8_t> const v_Z = {'[', '#', 'i', 2, 'Z', 'Z'};
                std::vector<uint8_t> const v_i = {'[', '#', 'i', 2, 'i', 0x7F, 'i', 0x7F};
                std::vector<uint8_t> const v_U = {'[', '#', 'i', 2, 'U', 0xFF, 'U', 0xFF};
                std::vector<uint8_t> const v_I = {'[', '#', 'i', 2, 'I', 0x7F, 0xFF, 'I', 0x7F, 0xFF};
                std::vector<uint8_t> const v_l = {'[', '#', 'i', 2, 'l', 0x7F, 0xFF, 0xFF, 0xFF, 'l', 0x7F, 0xFF, 0xFF, 0xFF};
                std::vector<uint8_t> const v_L = {'[', '#', 'i', 2, 'L', 0x7F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 'L', 0x7F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
                std::vector<uint8_t> const v_D = {'[', '#', 'i', 2, 'D', 0x40, 0x09, 0x21, 0xfb, 0x4d, 0x12, 0xd8, 0x4a, 'D', 0x40, 0x09, 0x21, 0xfb, 0x4d, 0x12, 0xd8, 0x4a};
                std::vector<uint8_t> const v_S = {'[', '#', 'i', 2, 'S', 'i', 1, 'a', 'S', 'i', 1, 'a'};
                std::vector<uint8_t> const v_C = {'[', '#', 'i', 2, 'C', 'a', 'C', 'a'};

                // check if vector is parsed correctly
                CHECK(json::from_ubjson(v_TU) == json({true, true}));
                CHECK(json::from_ubjson(v_T) == json({true, true}));
                CHECK(json::from_ubjson(v_F) == json({false, false}));
                CHECK(json::from_ubjson(v_Z) == json({nullptr, nullptr}));
                CHECK(json::from_ubjson(v_i) == json({127, 127}));
                CHECK(json::from_ubjson(v_U) == json({255, 255}));
                CHECK(json::from_ubjson(v_I) == json({32767, 32767}));
                CHECK(json::from_ubjson(v_l) == json({2147483647, 2147483647}));
                CHECK(json::from_ubjson(v_L) == json({9223372036854775807, 9223372036854775807}));
                CHECK(json::from_ubjson(v_D) == json({3.1415926, 3.1415926}));
                CHECK(json::from_ubjson(v_S) == json({"a", "a"}));
                CHECK(json::from_ubjson(v_C) == json({"a", "a"}));

                // roundtrip: output should be optimized
                CHECK(json::to_ubjson(json::from_ubjson(v_T), true) == v_T);
                CHECK(json::to_ubjson(json::from_ubjson(v_F), true) == v_F);
                CHECK(json::to_ubjson(json::from_ubjson(v_Z), true) == v_Z);
                CHECK(json::to_ubjson(json::from_ubjson(v_i), true) == v_i);
                CHECK(json::to_ubjson(json::from_ubjson(v_U), true) == v_U);
                CHECK(json::to_ubjson(json::from_ubjson(v_I), true) == v_I);
                CHECK(json::to_ubjson(json::from_ubjson(v_l), true) == v_l);
                CHECK(json::to_ubjson(json::from_ubjson(v_L), true) == v_L);
                CHECK(json::to_ubjson(json::from_ubjson(v_D), true) == v_D);
                CHECK(json::to_ubjson(json::from_ubjson(v_S), true) == v_S);
                CHECK(json::to_ubjson(json::from_ubjson(v_C), true) == v_S); // char is serialized to string
            }

            SECTION("optimized version (type and length)")
            {
                // create vector with two elements of the same type
                std::vector<uint8_t> const v_N = {'[', '$', 'N', '#', 'i', 2};
                std::vector<uint8_t> const v_T = {'[', '$', 'T', '#', 'i', 2};
                std::vector<uint8_t> const v_F = {'[', '$', 'F', '#', 'i', 2};
                std::vector<uint8_t> const v_Z = {'[', '$', 'Z', '#', 'i', 2};
                std::vector<uint8_t> const v_i = {'[', '$', 'i', '#', 'i', 2, 0x7F, 0x7F};
                std::vector<uint8_t> const v_U = {'[', '$', 'U', '#', 'i', 2, 0xFF, 0xFF};
                std::vector<uint8_t> const v_I = {'[', '$', 'I', '#', 'i', 2, 0x7F, 0xFF, 0x7F, 0xFF};
                std::vector<uint8_t> const v_l = {'[', '$', 'l', '#', 'i', 2, 0x7F, 0xFF, 0xFF, 0xFF, 0x7F, 0xFF, 0xFF, 0xFF};
                std::vector<uint8_t> const v_L = {'[', '$', 'L', '#', 'i', 2, 0x7F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x7F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
                std::vector<uint8_t> const v_D = {'[', '$', 'D', '#', 'i', 2, 0x40, 0x09, 0x21, 0xfb, 0x4d, 0x12, 0xd8, 0x4a, 0x40, 0x09, 0x21, 0xfb, 0x4d, 0x12, 0xd8, 0x4a};
                std::vector<uint8_t> const v_S = {'[', '$', 'S', '#', 'i', 2, 'i', 1, 'a', 'i', 1, 'a'};
                std::vector<uint8_t> const v_C = {'[', '$', 'C', '#', 'i', 2, 'a', 'a'};

                // check if vector is parsed correctly
                CHECK(json::from_ubjson(v_N) == json::array());
                CHECK(json::from_ubjson(v_T) == json({true, true}));
                CHECK(json::from_ubjson(v_F) == json({false, false}));
                CHECK(json::from_ubjson(v_Z) == json({nullptr, nullptr}));
                CHECK(json::from_ubjson(v_i) == json({127, 127}));
                CHECK(json::from_ubjson(v_U) == json({255, 255}));
                CHECK(json::from_ubjson(v_I) == json({32767, 32767}));
                CHECK(json::from_ubjson(v_l) == json({2147483647, 2147483647}));
                CHECK(json::from_ubjson(v_L) == json({9223372036854775807, 9223372036854775807}));
                CHECK(json::from_ubjson(v_D) == json({3.1415926, 3.1415926}));
                CHECK(json::from_ubjson(v_S) == json({"a", "a"}));
                CHECK(json::from_ubjson(v_C) == json({"a", "a"}));

                // roundtrip: output should be optimized
                std::vector<uint8_t> const v_empty = {'[', '#', 'i', 0};
                CHECK(json::to_ubjson(json::from_ubjson(v_N), true, true) == v_empty);
                CHECK(json::to_ubjson(json::from_ubjson(v_T), true, true) == v_T);
                CHECK(json::to_ubjson(json::from_ubjson(v_F), true, true) == v_F);
                CHECK(json::to_ubjson(json::from_ubjson(v_Z), true, true) == v_Z);
                CHECK(json::to_ubjson(json::from_ubjson(v_i), true, true) == v_i);
                CHECK(json::to_ubjson(json::from_ubjson(v_U), true, true) == v_U);
                CHECK(json::to_ubjson(json::from_ubjson(v_I), true, true) == v_I);
                CHECK(json::to_ubjson(json::from_ubjson(v_l), true, true) == v_l);
                CHECK(json::to_ubjson(json::from_ubjson(v_L), true, true) == v_L);
                CHECK(json::to_ubjson(json::from_ubjson(v_D), true, true) == v_D);
                CHECK(json::to_ubjson(json::from_ubjson(v_S), true, true) == v_S);
                CHECK(json::to_ubjson(json::from_ubjson(v_C), true, true) == v_S); // char is serialized to string
            }
        }
    }

    SECTION("parse errors")
    {
        SECTION("empty byte vector")
        {
            json _;
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(std::vector<uint8_t>()), "[json.exception.parse_error.110] parse error at byte 1: syntax error while parsing UBJSON value: unexpected end of input", json::parse_error&);
        }

        SECTION("char")
        {
            SECTION("eof after C byte")
            {
                std::vector<uint8_t> const v = {'C'};
                json _;
                CHECK_THROWS_WITH_AS(_ = json::from_ubjson(v), "[json.exception.parse_error.110] parse error at byte 2: syntax error while parsing UBJSON char: unexpected end of input", json::parse_error&);
            }

            SECTION("byte out of range")
            {
                std::vector<uint8_t> const v = {'C', 130};
                json _;
                CHECK_THROWS_WITH_AS(_ = json::from_ubjson(v), "[json.exception.parse_error.113] parse error at byte 2: syntax error while parsing UBJSON char: byte after 'C' must be in range 0x00..0x7F; last byte: 0x82", json::parse_error&);
            }
        }

        SECTION("strings")
        {
            SECTION("eof after S byte")
            {
                std::vector<uint8_t> const v = {'S'};
                json _;
                CHECK_THROWS_WITH_AS(_ = json::from_ubjson(v), "[json.exception.parse_error.110] parse error at byte 2: syntax error while parsing UBJSON value: unexpected end of input", json::parse_error&);
            }

            SECTION("invalid byte")
            {
                std::vector<uint8_t> const v = {'S', '1', 'a'};
                json _;
                CHECK_THROWS_WITH_AS(_ = json::from_ubjson(v), "[json.exception.parse_error.113] parse error at byte 2: syntax error while parsing UBJSON string: expected length type specification (U, i, I, l, L); last byte: 0x31", json::parse_error&);
            }

            SECTION("negative length")
            {
                json _;

                std::vector<uint8_t> const vi = {'S', 'i', 0xFF};
                CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vi), "[json.exception.parse_error.113] parse error at byte 3: syntax error while parsing UBJSON string: string length must not be negative", json::parse_error&);
                CHECK(json::from_ubjson(vi, true, false).is_discarded());

                std::vector<uint8_t> const vI = {'S', 'I', 0xFF, 0xFF};
                CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vI), "[json.exception.parse_error.113] parse error at byte 4: syntax error while parsing UBJSON string: string length must not be negative", json::parse_error&);
                CHECK(json::from_ubjson(vI, true, false).is_discarded());

                std::vector<uint8_t> const vl = {'S', 'l', 0xFF, 0xFF, 0xFF, 0xFF};
                CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vl), "[json.exception.parse_error.113] parse error at byte 6: syntax error while parsing UBJSON string: string length must not be negative", json::parse_error&);
                CHECK(json::from_ubjson(vl, true, false).is_discarded());

                std::vector<uint8_t> const vL = {'S', 'L', 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
                CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vL), "[json.exception.parse_error.113] parse error at byte 10: syntax error while parsing UBJSON string: string length must not be negative", json::parse_error&);
                CHECK(json::from_ubjson(vL, true, false).is_discarded());

                // a length of zero remains valid and yields an empty string
                std::vector<uint8_t> const v0 = {'S', 'i', 0};
                CHECK(json::from_ubjson(v0) == json(""));
            }
        }

        SECTION("array")
        {
            SECTION("optimized array: no size following type")
            {
                std::vector<uint8_t> const v = {'[', '$', 'i', 2};
                json _;
                CHECK_THROWS_WITH_AS(_ = json::from_ubjson(v), "[json.exception.parse_error.112] parse error at byte 4: syntax error while parsing UBJSON size: expected '#' after type information; last byte: 0x02", json::parse_error&);
            }
        }

        SECTION("strings")
        {
            std::vector<uint8_t> const vS = {'S'};
            json _;
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vS), "[json.exception.parse_error.110] parse error at byte 2: syntax error while parsing UBJSON value: unexpected end of input", json::parse_error&);
            CHECK(json::from_ubjson(vS, true, false).is_discarded());

            std::vector<uint8_t> const v = {'S', 'i', '2', 'a'};
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(v), "[json.exception.parse_error.110] parse error at byte 5: syntax error while parsing UBJSON string: unexpected end of input", json::parse_error&);
            CHECK(json::from_ubjson(v, true, false).is_discarded());

            std::vector<uint8_t> const vC = {'C'};
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vC), "[json.exception.parse_error.110] parse error at byte 2: syntax error while parsing UBJSON char: unexpected end of input", json::parse_error&);
            CHECK(json::from_ubjson(vC, true, false).is_discarded());
        }

        SECTION("sizes")
        {
            std::vector<uint8_t> const vU = {'[', '#', 'U'};
            json _;
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vU), "[json.exception.parse_error.110] parse error at byte 4: syntax error while parsing UBJSON number: unexpected end of input", json::parse_error&);
            CHECK(json::from_ubjson(vU, true, false).is_discarded());

            std::vector<uint8_t> const vi = {'[', '#', 'i'};
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vi), "[json.exception.parse_error.110] parse error at byte 4: syntax error while parsing UBJSON number: unexpected end of input", json::parse_error&);
            CHECK(json::from_ubjson(vi, true, false).is_discarded());

            std::vector<uint8_t> const vI = {'[', '#', 'I'};
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vI), "[json.exception.parse_error.110] parse error at byte 4: syntax error while parsing UBJSON number: unexpected end of input", json::parse_error&);
            CHECK(json::from_ubjson(vI, true, false).is_discarded());

            std::vector<uint8_t> const vl = {'[', '#', 'l'};
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vl), "[json.exception.parse_error.110] parse error at byte 4: syntax error while parsing UBJSON number: unexpected end of input", json::parse_error&);
            CHECK(json::from_ubjson(vl, true, false).is_discarded());

            std::vector<uint8_t> const vL = {'[', '#', 'L'};
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vL), "[json.exception.parse_error.110] parse error at byte 4: syntax error while parsing UBJSON number: unexpected end of input", json::parse_error&);
            CHECK(json::from_ubjson(vL, true, false).is_discarded());

            std::vector<uint8_t> const v0 = {'[', '#', 'T', ']'};
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(v0), "[json.exception.parse_error.113] parse error at byte 3: syntax error while parsing UBJSON size: expected length type specification (U, i, I, l, L) after '#'; last byte: 0x54", json::parse_error&);
            CHECK(json::from_ubjson(v0, true, false).is_discarded());
        }

        SECTION("types")
        {
            std::vector<uint8_t> const v0 = {'[', '$'};
            json _;
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(v0), "[json.exception.parse_error.110] parse error at byte 3: syntax error while parsing UBJSON type: unexpected end of input", json::parse_error&);
            CHECK(json::from_ubjson(v0, true, false).is_discarded());

            std::vector<uint8_t> const vi = {'[', '$', '#'};
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vi), "[json.exception.parse_error.112] parse error at byte 3: syntax error while parsing UBJSON type: marker 0x23 is not a permitted optimized array type", json::parse_error&);
            CHECK(json::from_ubjson(vi, true, false).is_discarded());

            std::vector<uint8_t> const vT = {'[', '$', 'T'};
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vT), "[json.exception.parse_error.110] parse error at byte 4: syntax error while parsing UBJSON value: unexpected end of input", json::parse_error&);
            CHECK(json::from_ubjson(vT, true, false).is_discarded());
        }

        SECTION("arrays")
        {
            std::vector<uint8_t> const vST = {'[', '$', 'i', '#', 'i', 2, 1};
            json _;
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vST), "[json.exception.parse_error.110] parse error at byte 8: syntax error while parsing UBJSON number: unexpected end of input", json::parse_error&);
            CHECK(json::from_ubjson(vST, true, false).is_discarded());

            std::vector<uint8_t> const vS = {'[', '#', 'i', 2, 'i', 1};
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vS), "[json.exception.parse_error.110] parse error at byte 7: syntax error while parsing UBJSON value: unexpected end of input", json::parse_error&);
            CHECK(json::from_ubjson(vS, true, false).is_discarded());

            std::vector<uint8_t> const v = {'[', 'i', 2, 'i', 1};
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(v), "[json.exception.parse_error.110] parse error at byte 6: syntax error while parsing UBJSON value: unexpected end of input", json::parse_error&);
            CHECK(json::from_ubjson(v, true, false).is_discarded());
        }

        SECTION("objects")
        {
            std::vector<uint8_t> const vST = {'{', '$', 'i', '#', 'i', 2, 'i', 1, 'a', 1};
            json _;
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vST), "[json.exception.parse_error.110] parse error at byte 11: syntax error while parsing UBJSON value: unexpected end of input", json::parse_error&);
            CHECK(json::from_ubjson(vST, true, false).is_discarded());

            std::vector<uint8_t> const vT = {'{', '$', 'i', 'i', 1, 'a', 1};
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vT), "[json.exception.parse_error.112] parse error at byte 4: syntax error while parsing UBJSON size: expected '#' after type information; last byte: 0x69", json::parse_error&);
            CHECK(json::from_ubjson(vT, true, false).is_discarded());

            std::vector<uint8_t> const vS = {'{', '#', 'i', 2, 'i', 1, 'a', 'i', 1};
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vS), "[json.exception.parse_error.110] parse error at byte 10: syntax error while parsing UBJSON value: unexpected end of input", json::parse_error&);
            CHECK(json::from_ubjson(vS, true, false).is_discarded());

            std::vector<uint8_t> const v = {'{', 'i', 1, 'a', 'i', 1};
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(v), "[json.exception.parse_error.110] parse error at byte 7: syntax error while parsing UBJSON value: unexpected end of input", json::parse_error&);
            CHECK(json::from_ubjson(v, true, false).is_discarded());

            std::vector<uint8_t> const v2 = {'{', 'i', 1, 'a', 'i', 1, 'i'};
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(v2), "[json.exception.parse_error.110] parse error at byte 8: syntax error while parsing UBJSON number: unexpected end of input", json::parse_error&);
            CHECK(json::from_ubjson(v2, true, false).is_discarded());

            std::vector<uint8_t> const v3 = {'{', 'i', 1, 'a'};
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(v3), "[json.exception.parse_error.110] parse error at byte 5: syntax error while parsing UBJSON value: unexpected end of input", json::parse_error&);
            CHECK(json::from_ubjson(v3, true, false).is_discarded());

            std::vector<uint8_t> const vST1 = {'{', '$', 'd', '#', 'i', 2, 'i', 1, 'a'};
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vST1), "[json.exception.parse_error.110] parse error at byte 10: syntax error while parsing UBJSON number: unexpected end of input", json::parse_error&);
            CHECK(json::from_ubjson(vST1, true, false).is_discarded());

            std::vector<uint8_t> const vST2 = {'{', '#', 'i', 2, 'i', 1, 'a'};
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(vST2), "[json.exception.parse_error.110] parse error at byte 8: syntax error while parsing UBJSON value: unexpected end of input", json::parse_error&);
            CHECK(json::from_ubjson(vST2, true, false).is_discarded());
        }
    }

    SECTION("writing optimized values")
    {
        SECTION("integer")
        {
            SECTION("array of i")
            {
                json const j = {1, -1};
                std::vector<uint8_t> expected = {'[', '$', 'i', '#', 'i', 2, 1, 0xff};
                CHECK(json::to_ubjson(j, true, true) == expected);
            }

            SECTION("array of U")
            {
                json const j = {200, 201};
                std::vector<uint8_t> expected = {'[', '$', 'U', '#', 'i', 2, 0xC8, 0xC9};
                CHECK(json::to_ubjson(j, true, true) == expected);
            }

            SECTION("array of I")
            {
                json const j = {30000, -30000};
                std::vector<uint8_t> expected = {'[', '$', 'I', '#', 'i', 2, 0x75, 0x30, 0x8a, 0xd0};
                CHECK(json::to_ubjson(j, true, true) == expected);
            }

            SECTION("array of l")
            {
                json const j = {70000, -70000};
                std::vector<uint8_t> expected = {'[', '$', 'l', '#', 'i', 2, 0x00, 0x01, 0x11, 0x70, 0xFF, 0xFE, 0xEE, 0x90};
                CHECK(json::to_ubjson(j, true, true) == expected);
            }

            SECTION("array of L")
            {
                json const j = {5000000000, -5000000000};
                std::vector<uint8_t> expected = {'[', '$', 'L', '#', 'i', 2, 0x00, 0x00, 0x00, 0x01, 0x2A, 0x05, 0xF2, 0x00, 0xFF, 0xFF, 0xFF, 0xFE, 0xD5, 0xFA, 0x0E, 0x00};
                CHECK(json::to_ubjson(j, true, true) == expected);
            }
        }

        SECTION("unsigned integer")
        {
            SECTION("array of i")
            {
                json const j = {1u, 2u};
                std::vector<uint8_t> expected = {'[', '$', 'i', '#', 'i', 2, 1, 2};
                std::vector<uint8_t> expected_size = {'[', '#', 'i', 2, 'i', 1, 'i', 2};
                CHECK(json::to_ubjson(j, true, true) == expected);
                CHECK(json::to_ubjson(j, true) == expected_size);
            }

            SECTION("array of U")
            {
                json const j = {200u, 201u};
                std::vector<uint8_t> expected = {'[', '$', 'U', '#', 'i', 2, 0xC8, 0xC9};
                std::vector<uint8_t> expected_size = {'[', '#', 'i', 2, 'U', 0xC8, 'U', 0xC9};
                CHECK(json::to_ubjson(j, true, true) == expected);
                CHECK(json::to_ubjson(j, true) == expected_size);
            }

            SECTION("array of I")
            {
                json const j = {30000u, 30001u};
                std::vector<uint8_t> expected = {'[', '$', 'I', '#', 'i', 2, 0x75, 0x30, 0x75, 0x31};
                std::vector<uint8_t> expected_size = {'[', '#', 'i', 2, 'I', 0x75, 0x30, 'I', 0x75, 0x31};
                CHECK(json::to_ubjson(j, true, true) == expected);
                CHECK(json::to_ubjson(j, true) == expected_size);
            }

            SECTION("array of l")
            {
                json const j = {70000u, 70001u};
                std::vector<uint8_t> expected = {'[', '$', 'l', '#', 'i', 2, 0x00, 0x01, 0x11, 0x70, 0x00, 0x01, 0x11, 0x71};
                std::vector<uint8_t> expected_size = {'[', '#', 'i', 2, 'l', 0x00, 0x01, 0x11, 0x70, 'l', 0x00, 0x01, 0x11, 0x71};
                CHECK(json::to_ubjson(j, true, true) == expected);
                CHECK(json::to_ubjson(j, true) == expected_size);
            }

            SECTION("array of L")
            {
                json const j = {5000000000u, 5000000001u};
                std::vector<uint8_t> expected = {'[', '$', 'L', '#', 'i', 2, 0x00, 0x00, 0x00, 0x01, 0x2A, 0x05, 0xF2, 0x00, 0x00, 0x00, 0x00, 0x01, 0x2A, 0x05, 0xF2, 0x01};
                std::vector<uint8_t> expected_size = {'[', '#', 'i', 2, 'L', 0x00, 0x00, 0x00, 0x01, 0x2A, 0x05, 0xF2, 0x00, 'L', 0x00, 0x00, 0x00, 0x01, 0x2A, 0x05, 0xF2, 0x01};
                CHECK(json::to_ubjson(j, true, true) == expected);
                CHECK(json::to_ubjson(j, true) == expected_size);
            }
        }

        SECTION("discarded")
        {
            // a discarded value cannot be serialized to UBJSON, even as part
            // of an optimized array of a single (here: valueless) type
            json const j = {json::value_t::discarded, json::value_t::discarded};
#if JSON_DIAGNOSTICS
            CHECK_THROWS_WITH_AS(json::to_ubjson(j, true, true), "[json.exception.type_error.321] (/0) cannot serialize discarded value to UBJSON", json::type_error&);
#else
            CHECK_THROWS_WITH_AS(json::to_ubjson(j, true, true), "[json.exception.type_error.321] cannot serialize discarded value to UBJSON", json::type_error&);
#endif
        }
    }
}

TEST_CASE("UBJSON nesting does not consume the call stack")
{
    // Containers used to be read by calling back into the value reader once
    // per element, so the native call stack grew with the nesting depth of the
    // input. '[' alone opens a container, so a payload of repeated '[' crashed
    // the process (#5104), as did the optimized forms, which reach the same
    // path through a type or size annotation. The containers are kept on a
    // heap stack now.
    //
    // Deeply nested values must not be compared, copied or dumped here: those
    // operations are still recursive and would reintroduce the crash.
    json _;

    SECTION("containers that end at a marker")
    {
        const std::vector<uint8_t> input(500000, '[');
        CHECK_THROWS_WITH_AS(_ = json::from_ubjson(input), "[json.exception.parse_error.110] parse error at byte 500001: syntax error while parsing UBJSON value: unexpected end of input", json::parse_error&);
        CHECK(json::from_ubjson(input, true, false).is_discarded());
    }

    SECTION("containers with a size")
    {
        std::vector<uint8_t> input;
        for (std::size_t i = 0; i < 100000; ++i)
        {
            input.push_back('[');
            input.push_back('#');
            input.push_back('i');
            input.push_back(1);
        }
        CHECK_THROWS_AS(_ = json::from_ubjson(input), json::parse_error&);
        CHECK(json::from_ubjson(input, true, false).is_discarded());
    }

    SECTION("containers with a type and a size")
    {
        // '[' is a permitted optimized type in UBJSON, so each element of such
        // a container is itself a container, read without a marker of its own
        std::vector<uint8_t> input;
        for (std::size_t i = 0; i < 100000; ++i)
        {
            const std::vector<uint8_t> level = {'[', '$', '[', '#', 'i', 1};
            input.insert(input.end(), level.begin(), level.end());
        }
        CHECK_THROWS_AS(_ = json::from_ubjson(input), json::parse_error&);
        CHECK(json::from_ubjson(input, true, false).is_discarded());
    }

    SECTION("a well-formed deep value is read through the SAX interface")
    {
        std::vector<uint8_t> input(100000, '[');
        input.insert(input.end(), 100000, ']');

        SaxCountdown accept_all(1000000);
        CHECK(json::sax_parse(input, &accept_all, json::input_format_t::ubjson));
    }

    SECTION("a well-formed deep value is read into a value")
    {
        const std::size_t depth = 10000;
        std::vector<uint8_t> input(depth, '[');
        input.insert(input.end(), depth, ']');

        json j = json::from_ubjson(input);

        std::size_t measured = 0;
        const json* p = &j;
        while (p->is_array() && !p->empty())
        {
            p = &p->front();
            ++measured;
        }
        // the innermost array is empty, so the descent stops one level short
        CHECK(measured == depth - 1);
    }

    SECTION("containers are still read the same way")
    {
        CHECK(json::from_ubjson(std::vector<uint8_t>({'[', ']'})) == json::array());
        CHECK(json::from_ubjson(std::vector<uint8_t>({'{', '}'})) == json::object());
        CHECK(json::from_ubjson(std::vector<uint8_t>({'[', '#', 'i', 0})) == json::array());
        CHECK(json::from_ubjson(std::vector<uint8_t>({'{', '#', 'i', 0})) == json::object());
        CHECK(json::from_ubjson(std::vector<uint8_t>({'[', '$', 'i', '#', 'i', 2, 1, 2})) == json({1, 2}));
        CHECK(json::from_ubjson(std::vector<uint8_t>({'[', '#', 'i', 2, 'i', 1, 'i', 2})) == json({1, 2}));
        CHECK(json::from_ubjson(std::vector<uint8_t>({'{', '$', 'i', '#', 'i', 1, 'i', 1, 'a', 1})) == json({{"a", 1}}));
        // a no-op is not a value, so a container of them holds none
        CHECK(json::from_ubjson(std::vector<uint8_t>({'[', '$', 'N', '#', 'i', 2})) == json::array());
        // sized and unsized forms nested inside one another
        CHECK(json::from_ubjson(std::vector<uint8_t>({'[', '[', '#', 'i', 2, 'i', 1, 'i', 2, ']'})) == json({{1, 2}}));
        CHECK(json::from_ubjson(std::vector<uint8_t>({'[', '#', 'i', 1, '[', 'i', 1, ']'})) == json({{1}}));
        // an optimized container of containers
        CHECK(json::from_ubjson(std::vector<uint8_t>({'[', '$', '[', '#', 'i', 2, 'i', 1, ']', 'i', 2, ']'})) == json({{1}, {2}}));
    }

    SECTION("BJData containers are still read the same way")
    {
        // the ND-array wrapper and the binary shortcut are complete values,
        // not containers the reader descends into
        CHECK(json::from_bjdata(std::vector<uint8_t>({'[', '$', 'U', '#', '[', '$', 'i', '#', 'i', 2, 2, 3, 1, 2, 3, 4, 5, 6})) ==
        json({{"_ArrayType_", "uint8"}, {"_ArraySize_", {2, 3}}, {"_ArrayData_", {1, 2, 3, 4, 5, 6}}}));
        CHECK(json::from_bjdata(std::vector<uint8_t>({'[', '$', 'i', '#', 'i', 2, 1, 2})) == json({1, 2}));
        CHECK(json::from_bjdata(std::vector<uint8_t>({'[', '[', 'i', 1, ']', ']'})) == json({{1}}));
    }
}

TEST_CASE("UBJSON input that cannot be read is discarded by every overload")
{
    std::vector<std::uint8_t> input = json::to_ubjson(json({{"a", {1, 2}}}));
    input.pop_back();

    json _;
    CHECK_THROWS_AS(_ = json::from_ubjson(input.begin(), input.end()), json::parse_error&);
    CHECK(json::from_ubjson(input, true, false).is_discarded());
    CHECK(json::from_ubjson(input.begin(), input.end(), true, false).is_discarded());
#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
    CHECK(json::from_ubjson(input.data(), input.size(), true, false).is_discarded());
    CHECK(json::from_ubjson({input.data(), input.size()}, true, false).is_discarded());
#endif
}

TEST_CASE("UBJSON SAX parsing stops at every event")
{
    // Containers are opened and closed by the loop that reads them; a SAX
    // handler that rejects any event - including the end of a nested
    // container - must stop the parse right there.
    const auto count_events = [](const std::vector<std::uint8_t>& input)
    {
        int events = 0;
        while (true)
        {
            SaxCountdown scp(events);
            if (json::sax_parse(input, &scp, json::input_format_t::ubjson))
            {
                return events;
            }
            ++events;
            REQUIRE(events < 1000);
        }
    };

    // 20 events: every container kind closes inside another one
    const json j = json::parse(R"({"a": [1, {"b": []}], "c": {"d": [[2]]}})");
    CHECK(count_events(json::to_ubjson(j)) == 20);
    CHECK(count_events(json::to_ubjson(j, true)) == 20);
    CHECK(count_events(json::to_ubjson(j, true, true)) == 20);
}

TEST_CASE("UBJSON optimized arrays of a valueless type are bounded")
{
    // An element of type 'Z', 'T' or 'F' is encoded by its marker alone, so an
    // optimized array of one of those has no payload and the declared count is
    // the only thing deciding how much is allocated. Ten bytes used to produce
    // billions of values (#2793); every other type costs at least one byte per
    // element and is bounded by the end of the input.
    json _;

    SECTION("an excessive count is rejected")
    {
        // 'l' is a big-endian int32: 0x7FFFFFFF elements, about 34 GB of value;
        // OSS-Fuzz reported this shape as a parse_ubjson_fuzzer timeout
        // (testcase 6347769435193344, no issue filed)
        for (const auto marker :
                {'Z', 'T', 'F'
                })
        {
            const std::vector<uint8_t> input = {'[', '$', static_cast<uint8_t>(marker), '#', 'l', 0x7F, 0xFF, 0xFF, 0xFF};
            CHECK_THROWS_WITH_AS(_ = json::from_ubjson(input), "[json.exception.out_of_range.408] syntax error while parsing UBJSON size: excessive array size", json::out_of_range&);
            CHECK(json::from_ubjson(input, true, false).is_discarded());
        }
    }

    SECTION("ordinary counts are unaffected")
    {
        CHECK(json::from_ubjson(std::vector<uint8_t>({'[', '$', 'Z', '#', 'i', 3})) == json({nullptr, nullptr, nullptr}));
        CHECK(json::from_ubjson(std::vector<uint8_t>({'[', '$', 'T', '#', 'i', 2})) == json({true, true}));
        CHECK(json::from_ubjson(std::vector<uint8_t>({'[', '$', 'F', '#', 'i', 2})) == json({false, false}));
        // 'N' is a no-op rather than a value, and still yields an empty array
        CHECK(json::from_ubjson(std::vector<uint8_t>({'[', '$', 'N', '#', 'i', 2})) == json::array());
    }

    SECTION("a type with a payload is unaffected")
    {
        // A count past the limit is not rejected for 'U', which costs a byte
        // per element and is bounded by the end of the input instead. The
        // count is kept just past the limit rather than made huge, because a
        // count that also exceeds the array's max_size() is reported as
        // out_of_range before the input runs out, and max_size() depends on
        // the width of std::size_t.
        const std::vector<uint8_t> input = {'[', '$', 'U', '#', 'l', 0x00, 0x10, 0x00, 0x01};
        CHECK_THROWS_WITH_AS(_ = json::from_ubjson(input), "[json.exception.parse_error.110] parse error at byte 10: syntax error while parsing UBJSON number: unexpected end of input", json::parse_error&);
        CHECK(json::from_ubjson(input, true, false).is_discarded());
    }

    SECTION("the writer stays within what the reader accepts")
    {
        // below the limit the optimized form is used and is tiny; above it the
        // writer falls back so that the result can still be read back
        json const at_limit(1048576, nullptr);
        const auto v_at_limit = json::to_ubjson(at_limit, true, true);
        CHECK(v_at_limit.size() == 9);
        CHECK(v_at_limit.at(1) == '$');
        CHECK(json::from_ubjson(v_at_limit) == at_limit);

        json const above_limit(1048577, nullptr);
        const auto v_above_limit = json::to_ubjson(above_limit, true, true);
        CHECK(v_above_limit.at(1) != '$');
        CHECK(json::from_ubjson(v_above_limit) == above_limit);
    }
}

TEST_CASE("issue #5405 - array reserve for definite-length UBJSON arrays")
{
#if !defined(JSON_NOEXCEPTION)
    // this SECTION relies on catching a thrown exception to distinguish
    // which of two acceptable, bounded rejections a hostile header took;
    // under JSON_NOEXCEPTION, JSON_THROW never produces a catchable C++
    // exception (it aborts instead), so this cannot be tested that way here
    SECTION("a huge claimed length with no element data must not over-allocate")
    {
        // optimized form [$type#count: type 'i' (int8), count as a four-byte
        // 'l' (int32) of 0x7FFFFFFF (2147483647), but no element data at all.
        // max_size() for a std::vector is far larger than this count, so it
        // does not reject the header outright; the (capped) reservation must
        // not attempt to allocate space for billions of elements before the
        // missing data is detected.
        json _;
        const std::vector<uint8_t> input = {'[', '$', 'i', '#', 'l', 0x7F, 0xFF, 0xFF, 0xFF};
        // On a platform where std::vector<json>::max_size() is smaller than
        // the claimed count (e.g. 32-bit, where max_size() is bounded by a
        // 32-bit SIZE_MAX divided by sizeof(json)), the SAX consumer's own
        // check rejects the header outright (out_of_range.408, with the
        // claimed count in the message) instead of accepting it and only
        // finding it short of data once the (capped) reservation looks for
        // element bytes that were never provided (parse_error.110). Either
        // is an acceptable, bounded rejection of the hostile header -- the
        // property under test is that no path attempts to allocate space
        // for billions of elements.
        bool threw = false;
        try
        {
            _ = json::from_ubjson(input);
        }
        catch (const json::parse_error& e)
        {
            threw = true;
            CHECK(e.id == 110);
            CHECK(std::string(e.what()) == "[json.exception.parse_error.110] parse error at byte 10: syntax error while parsing UBJSON number: unexpected end of input");
        }
        catch (const json::out_of_range& e)
        {
            threw = true;
            CHECK(e.id == 408);
            CHECK(std::string(e.what()).find("excessive array size") != std::string::npos);
        }
        CHECK(threw);

        // json_sax_dom_parser::start_array()'s max_size() check (unlike the
        // scanner's own parse_error path) throws unconditionally via
        // JSON_THROW rather than going through sax->parse_error(), so it is
        // not gated by allow_exceptions=false on a platform where this
        // header hits that check (e.g. 32-bit, see above) -- allow either
        // a discarded result or the same out_of_range it throws with
        // exceptions enabled.
        try
        {
            CHECK(json::from_ubjson(input, true, false).is_discarded());
        }
        catch (const json::out_of_range& e)
        {
            CHECK(e.id == 408);
        }
    }
#endif

    SECTION("arrays of various sizes decode to the same value as before the reserve optimization")
    {
        for (const auto size :
                {
                    std::size_t{0}, std::size_t{1}, std::size_t{5}, // small
                    std::size_t{16384},                             // exactly at the reserve cap
                    std::size_t{20000}                              // above the reserve cap
                })
        {
            CAPTURE(size)
            json j = json::array();
            for (std::size_t i = 0; i < size; ++i)
            {
                j.push_back(static_cast<int>(i % 1000));
            }

            // exercise both the plain and the optimized [$type#count encoding
            const auto packed_plain = json::to_ubjson(j);
            CHECK(json::from_ubjson(packed_plain) == j);

            const auto packed_optimized = json::to_ubjson(j, true, true);
            CHECK(json::from_ubjson(packed_optimized) == j);
        }
    }

    SECTION("a user-defined SAX consumer is unaffected by the internal DOM reserve optimization")
    {
        // the reserve() call is local to json_sax_dom_parser / json_sax_dom_callback_parser;
        // a custom SAX consumer that does not touch a DOM array sees identical events
        json j = json::array();
        for (int i = 0; i < 100; ++i)
        {
            j.push_back(i);
        }
        const auto packed = json::to_ubjson(j, true, true);

        SaxCountdown scp(1000000); // large enough to never trigger an abort
        CHECK(json::sax_parse(packed, &scp, json::input_format_t::ubjson));
    }
}


TEST_CASE("Universal Binary JSON Specification Examples 1")
{
    SECTION("Null Value")
    {
        json const j = {{"passcode", nullptr}};
        std::vector<uint8_t> const v = {'{', 'i', 8, 'p', 'a', 's', 's', 'c', 'o', 'd', 'e', 'Z', '}'};
        CHECK(json::to_ubjson(j) == v);
        CHECK(json::from_ubjson(v) == j);
    }

    SECTION("No-Op Value")
    {
        json const j = {"foo", "bar", "baz"};
        std::vector<uint8_t> const v = {'[', 'S', 'i', 3, 'f', 'o', 'o',
                                        'S', 'i', 3, 'b', 'a', 'r',
                                        'S', 'i', 3, 'b', 'a', 'z', ']'
                                       };
        std::vector<uint8_t> const v2 = {'[', 'S', 'i', 3, 'f', 'o', 'o', 'N',
                                         'S', 'i', 3, 'b', 'a', 'r', 'N', 'N', 'N',
                                         'S', 'i', 3, 'b', 'a', 'z', 'N', 'N', ']'
                                        };
        CHECK(json::to_ubjson(j) == v);
        CHECK(json::from_ubjson(v) == j);
        CHECK(json::from_ubjson(v2) == j);
    }

    SECTION("Boolean Types")
    {
        json const j = {{"authorized", true}, {"verified", false}};
        std::vector<uint8_t> const v = {'{', 'i', 10, 'a', 'u', 't', 'h', 'o', 'r', 'i', 'z', 'e', 'd', 'T',
                                        'i', 8, 'v', 'e', 'r', 'i', 'f', 'i', 'e', 'd', 'F', '}'
                                       };
        CHECK(json::to_ubjson(j) == v);
        CHECK(json::from_ubjson(v) == j);
    }

    SECTION("Numeric Types")
    {
        json const j =
        {
            {"int8", 16},
            {"uint8", 255},
            {"int16", 32767},
            {"int32", 2147483647},
            {"int64", 9223372036854775807},
            {"float64", 113243.7863123}
        };
        std::vector<uint8_t> const v = {'{',
                                        'i', 7, 'f', 'l', 'o', 'a', 't', '6', '4', 'D', 0x40, 0xfb, 0xa5, 0xbc, 0x94, 0xbc, 0x34, 0xcf,
                                        'i', 5, 'i', 'n', 't', '1', '6', 'I', 0x7f, 0xff,
                                        'i', 5, 'i', 'n', 't', '3', '2', 'l', 0x7f, 0xff, 0xff, 0xff,
                                        'i', 5, 'i', 'n', 't', '6', '4', 'L', 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
                                        'i', 4, 'i', 'n', 't', '8', 'i', 16,
                                        'i', 5, 'u', 'i', 'n', 't', '8', 'U', 0xff,
                                        '}'
                                       };
        CHECK(json::to_ubjson(j) == v);
        CHECK(json::from_ubjson(v) == j);
    }

    SECTION("Char Type")
    {
        json const j = {{"rolecode", "a"}, {"delim", ";"}};
        std::vector<uint8_t> const v = {'{', 'i', 5, 'd', 'e', 'l', 'i', 'm', 'C', ';', 'i', 8, 'r', 'o', 'l', 'e', 'c', 'o', 'd', 'e', 'C', 'a', '}'};
        //CHECK(json::to_ubjson(j) == v);
        CHECK(json::from_ubjson(v) == j);
    }

    SECTION("String Type")
    {
        SECTION("English")
        {
            json const j = "hello";
            std::vector<uint8_t> const v = {'S', 'i', 5, 'h', 'e', 'l', 'l', 'o'};
            CHECK(json::to_ubjson(j) == v);
            CHECK(json::from_ubjson(v) == j);
        }

        SECTION("Russian")
        {
            json const j = "привет";
            std::vector<uint8_t> const v = {'S', 'i', 12, 0xD0, 0xBF, 0xD1, 0x80, 0xD0, 0xB8, 0xD0, 0xB2, 0xD0, 0xB5, 0xD1, 0x82};
            CHECK(json::to_ubjson(j) == v);
            CHECK(json::from_ubjson(v) == j);
        }

        SECTION("Russian")
        {
            json const j = "مرحبا";
            std::vector<uint8_t> const v = {'S', 'i', 10, 0xD9, 0x85, 0xD8, 0xB1, 0xD8, 0xAD, 0xD8, 0xA8, 0xD8, 0xA7};
            CHECK(json::to_ubjson(j) == v);
            CHECK(json::from_ubjson(v) == j);
        }

        SECTION("ill-formed UTF-8 (see #5529, #5651)")
        {
            // none of the binary format specs requires a decoder to reject
            // ill-formed UTF-8 in a text string, so a value whose bytes are
            // not valid UTF-8 (0xC0 0xAE is an overlong encoding of '.')
            // round-trips byte for byte as a string value; to_ubjson() writes
            // the bytes unchanged, as before 3.13.0, unless
            // JSON_STRICT_BINARY_UTF8 is enabled (see
            // unit-binary_utf8_strict.cpp)
            const std::vector<uint8_t> v = {'S', 'i', 2, 0xc0, 0xae};
            json j;
            CHECK_NOTHROW(j = json::from_ubjson(v));
            REQUIRE(j.is_string());
            CHECK(j.get_ref<const json::string_t&>() == std::string("\xc0\xae"));
            CHECK_THROWS_AS(utils::ignore_return_value(j.dump()), json::type_error&);
            CHECK(json::from_ubjson(json::to_ubjson(j)) == j);

            // the same bytes as an object key round-trip as well
            const std::vector<uint8_t> v_key = {'{', 'i', 2, 0xc0, 0xae, 'i', 1, '}'};
            json j_key;
            CHECK_NOTHROW(j_key = json::from_ubjson(v_key));
            REQUIRE(j_key.is_object());
            CHECK(j_key.contains(std::string("\xc0\xae")));
            CHECK(json::from_ubjson(json::to_ubjson(j_key)) == j_key);

            CHECK(json::from_ubjson(json::to_ubjson(json("\xFF"))) == json("\xFF"));
            // a truncated multi-byte sequence
            CHECK(json::from_ubjson(json::to_ubjson(json("\xC3"))) == json("\xC3"));
            // an encoded surrogate half (U+D800)
            CHECK(json::from_ubjson(json::to_ubjson(json("\xED\xA0\x80"))) == json("\xED\xA0\x80"));
            // an overlong encoding of '.'
            CHECK(json::from_ubjson(json::to_ubjson(json("\xC0\xAF"))) == json("\xC0\xAF"));

            // an object key with ill-formed UTF-8 is kept the same way
            CHECK(json::from_ubjson(json::to_ubjson(json{{"\xFF", 1}})) == json{{"\xFF", 1}});
        }
    }

    SECTION("Array Type")
    {
        SECTION("size=false type=false")
        {
            // note the float has been replaced by a double
            json const j = {nullptr, true, false, 4782345193, 153.132, "ham"};
            std::vector<uint8_t> const v = {'[', 'Z', 'T', 'F', 'L', 0x00, 0x00, 0x00, 0x01, 0x1D, 0x0C, 0xCB, 0xE9, 'D', 0x40, 0x63, 0x24, 0x39, 0x58, 0x10, 0x62, 0x4e, 'S', 'i', 3, 'h', 'a', 'm', ']'};
            CHECK(json::to_ubjson(j) == v);
            CHECK(json::from_ubjson(v) == j);
        }

        SECTION("size=true type=false")
        {
            // note the float has been replaced by a double
            json const j = {nullptr, true, false, 4782345193, 153.132, "ham"};
            std::vector<uint8_t> const v = {'[', '#', 'i', 6, 'Z', 'T', 'F', 'L', 0x00, 0x00, 0x00, 0x01, 0x1D, 0x0C, 0xCB, 0xE9, 'D', 0x40, 0x63, 0x24, 0x39, 0x58, 0x10, 0x62, 0x4e, 'S', 'i', 3, 'h', 'a', 'm'};
            CHECK(json::to_ubjson(j, true) == v);
            CHECK(json::from_ubjson(v) == j);
        }

        SECTION("size=true type=true")
        {
            // note the float has been replaced by a double
            json const j = {nullptr, true, false, 4782345193, 153.132, "ham"};
            std::vector<uint8_t> const v = {'[', '#', 'i', 6, 'Z', 'T', 'F', 'L', 0x00, 0x00, 0x00, 0x01, 0x1D, 0x0C, 0xCB, 0xE9, 'D', 0x40, 0x63, 0x24, 0x39, 0x58, 0x10, 0x62, 0x4e, 'S', 'i', 3, 'h', 'a', 'm'};
            CHECK(json::to_ubjson(j, true, true) == v);
            CHECK(json::from_ubjson(v) == j);
        }
    }

    SECTION("Object Type")
    {
        SECTION("size=false type=false")
        {
            json const j =
            {
                {
                    "post", {
                        {"id", 1137},
                        {"author", "rkalla"},
                        {"timestamp", 1364482090592},
                        {"body", "I totally agree!"}
                    }
                }
            };
            std::vector<uint8_t> const v = {'{', 'i', 4, 'p', 'o', 's', 't', '{',
                                            'i', 6, 'a', 'u', 't', 'h', 'o', 'r', 'S', 'i', 6, 'r', 'k', 'a', 'l', 'l', 'a',
                                            'i', 4, 'b', 'o', 'd', 'y', 'S', 'i', 16, 'I', ' ', 't', 'o', 't', 'a', 'l', 'l', 'y', ' ', 'a', 'g', 'r', 'e', 'e', '!',
                                            'i', 2, 'i', 'd', 'I', 0x04, 0x71,
                                            'i', 9, 't', 'i', 'm', 'e', 's', 't', 'a', 'm', 'p', 'L', 0x00, 0x00, 0x01, 0x3D, 0xB1, 0x78, 0x66, 0x60,
                                            '}', '}'
                                           };
            CHECK(json::to_ubjson(j) == v);
            CHECK(json::from_ubjson(v) == j);
        }

        SECTION("size=true type=false")
        {
            json const j =
            {
                {
                    "post", {
                        {"id", 1137},
                        {"author", "rkalla"},
                        {"timestamp", 1364482090592},
                        {"body", "I totally agree!"}
                    }
                }
            };
            std::vector<uint8_t> const v = {'{', '#', 'i', 1, 'i', 4, 'p', 'o', 's', 't', '{', '#', 'i', 4,
                                            'i', 6, 'a', 'u', 't', 'h', 'o', 'r', 'S', 'i', 6, 'r', 'k', 'a', 'l', 'l', 'a',
                                            'i', 4, 'b', 'o', 'd', 'y', 'S', 'i', 16, 'I', ' ', 't', 'o', 't', 'a', 'l', 'l', 'y', ' ', 'a', 'g', 'r', 'e', 'e', '!',
                                            'i', 2, 'i', 'd', 'I', 0x04, 0x71,
                                            'i', 9, 't', 'i', 'm', 'e', 's', 't', 'a', 'm', 'p', 'L', 0x00, 0x00, 0x01, 0x3D, 0xB1, 0x78, 0x66, 0x60
                                           };
            CHECK(json::to_ubjson(j, true) == v);
            CHECK(json::from_ubjson(v) == j);
        }

        SECTION("size=true type=true")
        {
            json const j =
            {
                {
                    "post", {
                        {"id", 1137},
                        {"author", "rkalla"},
                        {"timestamp", 1364482090592},
                        {"body", "I totally agree!"}
                    }
                }
            };
            std::vector<uint8_t> const v = {'{', '$', '{', '#', 'i', 1, 'i', 4, 'p', 'o', 's', 't', '#', 'i', 4,
                                            'i', 6, 'a', 'u', 't', 'h', 'o', 'r', 'S', 'i', 6, 'r', 'k', 'a', 'l', 'l', 'a',
                                            'i', 4, 'b', 'o', 'd', 'y', 'S', 'i', 16, 'I', ' ', 't', 'o', 't', 'a', 'l', 'l', 'y', ' ', 'a', 'g', 'r', 'e', 'e', '!',
                                            'i', 2, 'i', 'd', 'I', 0x04, 0x71,
                                            'i', 9, 't', 'i', 'm', 'e', 's', 't', 'a', 'm', 'p', 'L', 0x00, 0x00, 0x01, 0x3D, 0xB1, 0x78, 0x66, 0x60
                                           };
            CHECK(json::to_ubjson(j, true, true) == v);
            CHECK(json::from_ubjson(v) == j);
        }
    }

    SECTION("Optimized Format")
    {
        SECTION("Array Example")
        {
            SECTION("No Optimization")
            {
                // note the floats have been replaced by doubles
                json const j = {29.97, 31.13, 67.0, 2.113, 23.888};
                std::vector<uint8_t> const v = {'[',
                                                'D', 0x40, 0x3d, 0xf8, 0x51, 0xeb, 0x85, 0x1e, 0xb8,
                                                'D', 0x40, 0x3f, 0x21, 0x47, 0xae, 0x14, 0x7a, 0xe1,
                                                'D', 0x40, 0x50, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00,
                                                'D', 0x40, 0x00, 0xe7, 0x6c, 0x8b, 0x43, 0x95, 0x81,
                                                'D', 0x40, 0x37, 0xe3, 0x53, 0xf7, 0xce, 0xd9, 0x17,
                                                ']'
                                               };
                CHECK(json::to_ubjson(j) == v);
                CHECK(json::from_ubjson(v) == j);
            }

            SECTION("Optimized with count")
            {
                // note the floats have been replaced by doubles
                json const j = {29.97, 31.13, 67.0, 2.113, 23.888};
                std::vector<uint8_t> const v = {'[', '#', 'i', 5,
                                                'D', 0x40, 0x3d, 0xf8, 0x51, 0xeb, 0x85, 0x1e, 0xb8,
                                                'D', 0x40, 0x3f, 0x21, 0x47, 0xae, 0x14, 0x7a, 0xe1,
                                                'D', 0x40, 0x50, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00,
                                                'D', 0x40, 0x00, 0xe7, 0x6c, 0x8b, 0x43, 0x95, 0x81,
                                                'D', 0x40, 0x37, 0xe3, 0x53, 0xf7, 0xce, 0xd9, 0x17
                                               };
                CHECK(json::to_ubjson(j, true) == v);
                CHECK(json::from_ubjson(v) == j);
            }

            SECTION("Optimized with type & count")
            {
                // note the floats have been replaced by doubles
                json const j = {29.97, 31.13, 67.0, 2.113, 23.888};
                std::vector<uint8_t> const v = {'[', '$', 'D', '#', 'i', 5,
                                                0x40, 0x3d, 0xf8, 0x51, 0xeb, 0x85, 0x1e, 0xb8,
                                                0x40, 0x3f, 0x21, 0x47, 0xae, 0x14, 0x7a, 0xe1,
                                                0x40, 0x50, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00,
                                                0x40, 0x00, 0xe7, 0x6c, 0x8b, 0x43, 0x95, 0x81,
                                                0x40, 0x37, 0xe3, 0x53, 0xf7, 0xce, 0xd9, 0x17
                                               };
                CHECK(json::to_ubjson(j, true, true) == v);
                CHECK(json::from_ubjson(v) == j);
            }
        }

        SECTION("Object Example")
        {
            SECTION("No Optimization")
            {
                // note the floats have been replaced by doubles
                json const j = { {"lat", 29.976}, {"long", 31.131}, {"alt", 67.0} };
                std::vector<uint8_t> const v = {'{',
                                                'i', 3, 'a', 'l', 't', 'D', 0x40, 0x50, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00,
                                                'i', 3, 'l', 'a', 't', 'D', 0x40, 0x3d, 0xf9, 0xdb, 0x22, 0xd0, 0xe5, 0x60,
                                                'i', 4, 'l', 'o', 'n', 'g', 'D', 0x40, 0x3f, 0x21, 0x89, 0x37, 0x4b, 0xc6, 0xa8,
                                                '}'
                                               };
                CHECK(json::to_ubjson(j) == v);
                CHECK(json::from_ubjson(v) == j);
            }

            SECTION("Optimized with count")
            {
                // note the floats have been replaced by doubles
                json const j = { {"lat", 29.976}, {"long", 31.131}, {"alt", 67.0} };
                std::vector<uint8_t> const v = {'{', '#', 'i', 3,
                                                'i', 3, 'a', 'l', 't', 'D', 0x40, 0x50, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00,
                                                'i', 3, 'l', 'a', 't', 'D', 0x40, 0x3d, 0xf9, 0xdb, 0x22, 0xd0, 0xe5, 0x60,
                                                'i', 4, 'l', 'o', 'n', 'g', 'D', 0x40, 0x3f, 0x21, 0x89, 0x37, 0x4b, 0xc6, 0xa8
                                               };
                CHECK(json::to_ubjson(j, true) == v);
                CHECK(json::from_ubjson(v) == j);
            }

            SECTION("Optimized with type & count")
            {
                // note the floats have been replaced by doubles
                json const j = { {"lat", 29.976}, {"long", 31.131}, {"alt", 67.0} };
                std::vector<uint8_t> const v = {'{', '$', 'D', '#', 'i', 3,
                                                'i', 3, 'a', 'l', 't', 0x40, 0x50, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00,
                                                'i', 3, 'l', 'a', 't', 0x40, 0x3d, 0xf9, 0xdb, 0x22, 0xd0, 0xe5, 0x60,
                                                'i', 4, 'l', 'o', 'n', 'g', 0x40, 0x3f, 0x21, 0x89, 0x37, 0x4b, 0xc6, 0xa8
                                               };
                CHECK(json::to_ubjson(j, true, true) == v);
                CHECK(json::from_ubjson(v) == j);
            }
        }

        SECTION("Special Cases (Null, No-Op and Boolean)")
        {
            SECTION("Array")
            {
                std::vector<uint8_t> const v = {'[', '$', 'N', '#', 'I', 0x02, 0x00};
                CHECK(json::from_ubjson(v) == json::array());
            }

            SECTION("Object")
            {
                std::vector<uint8_t> const v = {'{', '$', 'Z', '#', 'i', 3, 'i', 4, 'n', 'a', 'm', 'e', 'i', 8, 'p', 'a', 's', 's', 'w', 'o', 'r', 'd', 'i', 5, 'e', 'm', 'a', 'i', 'l'};
                CHECK(json::from_ubjson(v) == json({ {"name", nullptr}, {"password", nullptr}, {"email", nullptr} }));
            }
        }
    }
}

TEST_CASE("Parse UBJSON directly from a file using iterator and sentinel")
{
    std::string const filename = TEST_DATA_DIRECTORY "/json_testsuite/sample.json.ubjson";
    std::ifstream file(filename, std::ios::binary);
    const std::istreambuf_iterator<char> first(file);
    const json parsed = json::from_ubjson(first, utils::istreambuf_sentinel{});
    CHECK((parsed.is_object() || parsed.is_array()));
}

#if !defined(JSON_NOEXCEPTION)
TEST_CASE("all UBJSON first bytes")
{
    // these bytes will fail immediately with exception parse_error.112
    std::set<uint8_t> supported =
    {
        'T', 'F', 'Z', 'U', 'i', 'I', 'l', 'L', 'd', 'D', 'C', 'S', '[', '{', 'N', 'H'
    };

    for (auto i = 0; i < 256; ++i)
    {
        const auto byte = static_cast<uint8_t>(i);
        CAPTURE(byte)

        try
        {
            auto res = json::from_ubjson(std::vector<uint8_t>(1, byte));
        }
        catch (const json::parse_error& e)
        {
            // check that parse_error.112 is only thrown if the
            // first byte is not in the supported set
            INFO_WITH_TEMP(e.what());
            if (supported.find(byte) == supported.end())
            {
                CHECK(e.id == 112);
            }
            else
            {
                CHECK(e.id != 112);
            }
        }
    }
}
#endif

TEST_CASE("UBJSON use_type requires use_size")
{
    SECTION("non-empty array throws other_error.502")
    {
        const json j = {1, 2, 3};
        CHECK_THROWS_WITH_AS(json::to_ubjson(j, false, true),
                             "[json.exception.other_error.502] use_type requires use_size = true",
                             json::other_error&);
    }

    SECTION("non-empty object throws other_error.502")
    {
        const json j = {{"a", 1}, {"b", 2}};
        CHECK_THROWS_WITH_AS(json::to_ubjson(j, false, true),
                             "[json.exception.other_error.502] use_type requires use_size = true",
                             json::other_error&);
    }

    SECTION("scalars do not throw with use_type=true, use_count=false")
    {
        CHECK_NOTHROW(json::to_ubjson(42, false, true));
        CHECK_NOTHROW(json::to_ubjson(3.14, false, true));
        CHECK_NOTHROW(json::to_ubjson("hello", false, true));
        CHECK_NOTHROW(json::to_ubjson(true, false, true));
        CHECK_NOTHROW(json::to_ubjson(nullptr, false, true));
    }

    SECTION("empty containers do not throw with use_type=true, use_count=false")
    {
        CHECK_NOTHROW(json::to_ubjson(json::array(), false, true));
        CHECK_NOTHROW(json::to_ubjson(json::object(), false, true));
    }

    SECTION("valid combinations on non-empty containers")
    {
        const json j = {1, 2, 3};
        CHECK_NOTHROW(json::to_ubjson(j, false, false));
        CHECK_NOTHROW(json::to_ubjson(j, true, false));
        CHECK_NOTHROW(json::to_ubjson(j, true, true));
    }
}

TEST_CASE("UBJSON round-trip invariants")
{
    // This checks what the parse_ubjson_fuzzer driver checks (see
    // tests/src/fuzzer-parse_ubjson.cpp), so that a regression shows up in CI
    // rather than as an OSS-Fuzz report: every value from_ubjson() returns
    // (j1) can be serialized with any combination of options, the result can
    // be parsed back (j2), and serializing j2 again with the same options
    // reproduces the exact bytes. Beyond the driver, this also checks that j2
    // equals j1. Values are compared with dump() rather than operator==,
    // because a NaN never compares equal to itself.
    struct options
    {
        bool use_size;
        bool use_type;
    };
    const std::vector<options> all_options =
    {
        {false, false},
        {true, false},
        {true, true},
    };

    for (const auto& j0 : utils::round_trip_corpus::values())
    {
        // turn the corpus value into a value as from_ubjson() returns it; this
        // has no binary values, as UBJSON writes them as arrays of integers
        for (const auto& initial : all_options)
        {
            const json j1 = json::from_ubjson(json::to_ubjson(j0, initial.use_size, initial.use_type));

            for (const auto& o : all_options)
            {
                INFO("j1 = " << j1.dump() << ", use_size = " << o.use_size << ", use_type = " << o.use_type);

                const std::vector<std::uint8_t> vec = json::to_ubjson(j1, o.use_size, o.use_type);
                json j2;
                // anything the library writes must be parsable by the library
                REQUIRE_NOTHROW(j2 = json::from_ubjson(vec));
                CHECK(j2.dump() == j1.dump());
                CHECK(json::to_ubjson(j2, o.use_size, o.use_type) == vec);
            }
        }
    }
}

TEST_CASE("UBJSON roundtrips" * doctest::skip())
{
    SECTION("input from self-generated UBJSON files")
    {
        for (std::string filename :
                {
                    TEST_DATA_DIRECTORY "/json_nlohmann_tests/all_unicode.json",
                    TEST_DATA_DIRECTORY "/json.org/1.json",
                    TEST_DATA_DIRECTORY "/json.org/2.json",
                    TEST_DATA_DIRECTORY "/json.org/3.json",
                    TEST_DATA_DIRECTORY "/json.org/4.json",
                    TEST_DATA_DIRECTORY "/json.org/5.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip01.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip02.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip03.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip04.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip05.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip06.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip07.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip08.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip09.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip10.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip11.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip12.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip13.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip14.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip15.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip16.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip17.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip18.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip19.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip20.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip21.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip22.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip23.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip24.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip25.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip26.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip27.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip28.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip29.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip30.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip31.json",
                    TEST_DATA_DIRECTORY "/json_roundtrip/roundtrip32.json",
                    TEST_DATA_DIRECTORY "/json_testsuite/sample.json",
                    TEST_DATA_DIRECTORY "/json_tests/pass1.json",
                    TEST_DATA_DIRECTORY "/json_tests/pass2.json",
                    TEST_DATA_DIRECTORY "/json_tests/pass3.json"
                })
        {
            CAPTURE(filename)

            std::ifstream f_json(filename);
            json const j1 = json::parse(f_json);
            auto const packed = utils::read_binary_file(filename + ".ubjson");

            {
                INFO_WITH_TEMP(filename + ": std::vector<uint8_t>");
                json j2;
                CHECK_NOTHROW(j2 = json::from_ubjson(packed));
                CHECK(j1 == j2);
            }

            {
                INFO_WITH_TEMP(filename + ": std::ifstream");
                std::ifstream f_ubjson(filename + ".ubjson", std::ios::binary);
                json j2;
                CHECK_NOTHROW(j2 = json::from_ubjson(f_ubjson));
                CHECK(j1 == j2);
            }

#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
            {
                INFO_WITH_TEMP(filename + ": uint8_t* and size");
                json j2;
                CHECK_NOTHROW(j2 = json::from_ubjson({packed.data(), packed.size()}));
                CHECK(j1 == j2);
            }
#endif

            {
                INFO_WITH_TEMP(filename + ": output to output adapters");
                {
                    INFO_WITH_TEMP(filename + ": output adapters: std::vector<uint8_t>");
                    std::vector<uint8_t> vec;
                    json::to_ubjson(j1, vec);
                    CHECK(vec == packed);
                }
            }
        }
    }
}

TEST_CASE("UBJSON optimized array of unsigned integers beyond int64")
{
    // UBJSON has no unsigned 64-bit type, so such values are written as
    // high-precision numbers - also as the type of an optimized container
    const json j = {18446744073709551615ULL, 9223372036854775808ULL};
    const std::vector<std::uint8_t> expected =
    {
        '[', '$', 'H', '#', 'i', 2,
        'i', 20, '1', '8', '4', '4', '6', '7', '4', '4', '0', '7', '3', '7', '0', '9', '5', '5', '1', '6', '1', '5',
        'i', 19, '9', '2', '2', '3', '3', '7', '2', '0', '3', '6', '8', '5', '4', '7', '7', '5', '8', '0', '8'
    };
    CHECK(json::to_ubjson(j, true, true) == expected);
    CHECK(json::from_ubjson(expected) == j);
}

namespace
{
// the bytes that follow the marker of an integer: the value in the width of
// the marker (big endian for UBJSON, little endian for BJData), or, for a
// high-precision number, the length and the decimal digits
std::vector<std::uint8_t> integer_payload(const char marker, const json& value, const bool little_endian)
{
    std::size_t width = 0;
    switch (marker)
    {
        case 'i':
        case 'U':
            width = 1;
            break;
        case 'I':
        case 'u':
            width = 2;
            break;
        case 'l':
        case 'm':
            width = 4;
            break;
        case 'L':
        case 'M':
            width = 8;
            break;
        default:
        {
            const std::string digits = value.dump();
            std::vector<std::uint8_t> result = {'i', static_cast<std::uint8_t>(digits.size())};
            for (const char c : digits)
            {
                result.push_back(static_cast<std::uint8_t>(c));
            }
            return result;
        }
    }

    const std::uint64_t bits = value.is_number_unsigned()
                               ? value.get<std::uint64_t>()
                               : static_cast<std::uint64_t>(value.get<std::int64_t>());
    std::vector<std::uint8_t> result(width);
    for (std::size_t i = 0; i < width; ++i)
    {
        result[little_endian ? i : width - 1 - i] = static_cast<std::uint8_t>(bits >> (8 * i));
    }
    return result;
}

json i64(const std::int64_t v)
{
    return v;
}

json u64(const std::uint64_t v)
{
    return v;
}
} // namespace

TEST_CASE("UBJSON and BJData integer markers at every range edge")
{
    // An optimized container announces the marker of its values after `$` and
    // then writes every value without a marker, so the marker the writer
    // announces and the width it writes must match for every value. This
    // checks both for the values around each edge of the integer types, as
    // scalars and as the values of optimized arrays and objects.
    struct integer_case
    {
        json value;
        char ubjson; // expected UBJSON marker
        char bjdata; // expected BJData marker
    };

    const std::int64_t int64_min = (std::numeric_limits<std::int64_t>::min)();
    const std::int64_t int64_max = (std::numeric_limits<std::int64_t>::max)();
    const std::uint64_t uint64_max = (std::numeric_limits<std::uint64_t>::max)();

    const std::vector<integer_case> cases =
    {
        // int8
        {i64(-129), 'I', 'I'},
        {i64(-128), 'i', 'i'},
        {i64(-127), 'i', 'i'},
        {i64(-1), 'i', 'i'},
        {i64(0), 'i', 'i'},
        {u64(0), 'i', 'i'},
        {i64(126), 'i', 'i'},
        {i64(127), 'i', 'i'},
        {u64(127), 'i', 'i'},
        {i64(128), 'U', 'U'},
        {u64(128), 'U', 'U'},
        // uint8
        {i64(254), 'U', 'U'},
        {i64(255), 'U', 'U'},
        {u64(255), 'U', 'U'},
        {i64(256), 'I', 'I'},
        {u64(256), 'I', 'I'},
        // int16
        {i64(-32769), 'l', 'l'},
        {i64(-32768), 'I', 'I'},
        {i64(-32767), 'I', 'I'},
        {i64(32766), 'I', 'I'},
        {i64(32767), 'I', 'I'},
        {u64(32767), 'I', 'I'},
        {i64(32768), 'l', 'u'},
        {u64(32768), 'l', 'u'},
        // uint16 (BJData only)
        {i64(65534), 'l', 'u'},
        {i64(65535), 'l', 'u'},
        {u64(65535), 'l', 'u'},
        {i64(65536), 'l', 'l'},
        {u64(65536), 'l', 'l'},
        // int32
        {i64(-2147483649LL), 'L', 'L'},
        {i64(-2147483648LL), 'l', 'l'},
        {i64(-2147483647LL), 'l', 'l'},
        {i64(2147483646LL), 'l', 'l'},
        {i64(2147483647LL), 'l', 'l'},
        {u64(2147483647ULL), 'l', 'l'},
        {i64(2147483648LL), 'L', 'm'},
        {u64(2147483648ULL), 'L', 'm'},
        // uint32 (BJData only)
        {i64(4294967294LL), 'L', 'm'},
        {i64(4294967295LL), 'L', 'm'},
        {u64(4294967295ULL), 'L', 'm'},
        {i64(4294967296LL), 'L', 'L'},
        {u64(4294967296ULL), 'L', 'L'},
        // int64
        {i64(int64_min), 'L', 'L'},
        {i64(int64_min + 1), 'L', 'L'},
        {i64(int64_max - 1), 'L', 'L'},
        {i64(int64_max), 'L', 'L'},
        {u64(static_cast<std::uint64_t>(int64_max)), 'L', 'L'},
        // uint64 (BJData only; UBJSON writes a high-precision number)
        {u64(static_cast<std::uint64_t>(int64_max) + 1), 'H', 'M'},
        {u64(uint64_max - 1), 'H', 'M'},
        {u64(uint64_max), 'H', 'M'},
    };

    for (const auto& c : cases)
    {
        for (const bool bjdata :
                {
                    false, true
                })
        {
            const char marker = bjdata ? c.bjdata : c.ubjson;
            const std::vector<std::uint8_t> payload = integer_payload(marker, c.value, bjdata);
            const auto to_binary = [bjdata](const json & j, const bool use_size, const bool use_type)
            {
                return bjdata ? json::to_bjdata(j, use_size, use_type) : json::to_ubjson(j, use_size, use_type);
            };
            const auto from_binary = [bjdata](const std::vector<std::uint8_t>& v)
            {
                return bjdata ? json::from_bjdata(v) : json::from_ubjson(v);
            };
            INFO("value = " << c.value.dump() << (c.value.is_number_unsigned() ? " (unsigned)" : "") << ", format = " << (bjdata ? "BJData" : "UBJSON"));

            // scalar
            std::vector<std::uint8_t> expected = {static_cast<std::uint8_t>(marker)};
            expected.insert(expected.end(), payload.begin(), payload.end());
            for (const bool use_size :
                    {
                        false, true
                    })
            {
                CHECK(to_binary(c.value, use_size, false) == expected);
            }
            CHECK(from_binary(expected) == c.value);

            const json arr = {c.value, c.value, c.value};

            // array without count or type: every value has its marker
            expected = {'['};
            for (int i = 0; i < 3; ++i)
            {
                expected.push_back(static_cast<std::uint8_t>(marker));
                expected.insert(expected.end(), payload.begin(), payload.end());
            }
            expected.push_back(']');
            CHECK(to_binary(arr, false, false) == expected);
            CHECK(from_binary(expected) == arr);

            // array with count: every value has its marker
            expected = {'[', '#', 'i', 3};
            for (int i = 0; i < 3; ++i)
            {
                expected.push_back(static_cast<std::uint8_t>(marker));
                expected.insert(expected.end(), payload.begin(), payload.end());
            }
            CHECK(to_binary(arr, true, false) == expected);
            CHECK(from_binary(expected) == arr);

            // array with type and count: the marker once, then the payloads
            expected = {'[', '$', static_cast<std::uint8_t>(marker), '#', 'i', 3};
            for (int i = 0; i < 3; ++i)
            {
                expected.insert(expected.end(), payload.begin(), payload.end());
            }
            CHECK(to_binary(arr, true, true) == expected);
            CHECK(from_binary(expected) == arr);

            // object with type and count: the marker once, then key and payload
            const json obj = {{"a", c.value}, {"b", c.value}};
            expected = {'{', '$', static_cast<std::uint8_t>(marker), '#', 'i', 2};
            for (const char key :
                    {'a', 'b'
                    })
            {
                expected.push_back('i');
                expected.push_back(1);
                expected.push_back(static_cast<std::uint8_t>(key));
                expected.insert(expected.end(), payload.begin(), payload.end());
            }
            CHECK(to_binary(obj, true, true) == expected);
            CHECK(from_binary(expected) == obj);
        }
    }
}

TEST_CASE("UBJSON large strings (chunked reader)")
{
    // get_ubjson_string() reads through get_string(), which reads in bounded
    // chunks (binary_reader.hpp, chunk_size == 4096); make sure roundtripping
    // is correct for lengths around and beyond that chunk size, for both
    // vector (iterator) and pointer inputs.
    //
    // A binary value is not included here: plain UBJSON (unlike BJData, see
    // the "BJData large strings and binaries" test) has no reader-side binary
    // type, so even the optimized uint8_t-array encoding of a binary value is
    // read back element-by-element as a JSON array of numbers rather than
    // through get_binary() - it never reaches the chunked path this test is
    // about (see the "roundtrip only works to an array of numbers" case
    // above).
    for (const std::size_t len :
            {
                std::size_t{0}, std::size_t{1}, std::size_t{4095}, std::size_t{4096},
                std::size_t{4097}, std::size_t{8192}, std::size_t{100000}
            })
    {
        CAPTURE(len)

        const json j_string = std::string(len, 'x');
        const std::vector<std::uint8_t> v_string = json::to_ubjson(j_string);
        CHECK(json::from_ubjson(v_string) == j_string);
        // pointer input exercises the std::memcpy fast path
        CHECK(json::from_ubjson(reinterpret_cast<const char*>(v_string.data()),
                                reinterpret_cast<const char*>(v_string.data()) + v_string.size()) == j_string);

        // a truncated payload must still be reported as an error
        if (len > 16)
        {
            std::vector<std::uint8_t> truncated = v_string;
            truncated.resize(truncated.size() - 8);
            json _;
            CHECK_THROWS_AS(_ = json::from_ubjson(truncated), json::parse_error);
        }
    }
}

TEST_CASE("UBJSON optimized container type marker is validated for count 0")
{
    // the '$' type marker must be a legal marker even if no element follows
    SECTION("invalid marker")
    {
        for (const char marker :
                {'x', 'E', 'B', 'u', 'm', 'M', 'h'
                })
        {
            for (const char open :
                    {'[', '{'
                    })
            {
                for (const int count :
                        {
                            0, 1
                        })
                {
                    CAPTURE(marker)
                    CAPTURE(open)
                    CAPTURE(count)
                    const std::vector<std::uint8_t> v = {static_cast<std::uint8_t>(open), '$', static_cast<std::uint8_t>(marker), '#', 'i', static_cast<std::uint8_t>(count)};
                    json _;
                    CHECK_THROWS_AS(_ = json::from_ubjson(v), json::parse_error&);
                    CHECK(json::from_ubjson(v, true, false).is_discarded());
                }
            }
        }
    }

    SECTION("error message")
    {
        const std::vector<std::uint8_t> v = {'[', '$', 'x', '#', 'i', 0};
        json _;
        CHECK_THROWS_WITH_AS(_ = json::from_ubjson(v), "[json.exception.parse_error.112] parse error at byte 3: syntax error while parsing UBJSON type: marker 0x78 is not a permitted optimized array type", json::parse_error&);
    }

    SECTION("valid marker")
    {
        for (const char marker :
                {'Z', 'N', 'T', 'F', 'i', 'U', 'I', 'l', 'L', 'd', 'D', 'H', 'C', 'S', '[', '{'
                })
        {
            CAPTURE(marker)
            const std::vector<std::uint8_t> va = {'[', '$', static_cast<std::uint8_t>(marker), '#', 'i', 0};
            const std::vector<std::uint8_t> vo = {'{', '$', static_cast<std::uint8_t>(marker), '#', 'i', 0};
            CHECK(json::from_ubjson(va) == json::array());
            CHECK(json::from_ubjson(vo) == json::object());
        }
    }
}