json/tests/src/unit-conversions.cpp

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

// cmake/test.cmake selects the C++ standard versions with which to build a
// unit test based on the presence of JSON_HAS_CPP_<VERSION> macros.
// When using macros that are only defined for particular versions of the standard
// (e.g., JSON_HAS_FILESYSTEM for C++17 and up), please mention the corresponding
// version macro in a comment close by, like this:
// JSON_HAS_CPP_<VERSION> (do not remove; see note at top of file)

#include "doctest_compatibility.h"

// skip tests if JSON_DisableEnumSerialization=ON (#4384)
#if defined(JSON_DISABLE_ENUM_SERIALIZATION) && (JSON_DISABLE_ENUM_SERIALIZATION == 1)
    #define SKIP_TESTS_FOR_ENUM_SERIALIZATION
#endif

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

#include <deque>
#include <forward_list>
#include <list>
#include <set>
#include <unordered_map>
#include <unordered_set>
#include <valarray>

// NLOHMANN_JSON_SERIALIZE_ENUM uses a static std::pair
DOCTEST_CLANG_SUPPRESS_WARNING_PUSH
DOCTEST_CLANG_SUPPRESS_WARNING("-Wexit-time-destructors")

#if (defined(__cplusplus) && __cplusplus >= 201703L) || (defined(_HAS_CXX17) && _HAS_CXX17 == 1) // fix for issue #464
    #define JSON_HAS_CPP_17
    #define JSON_HAS_CPP_14
#elif (defined(__cplusplus) && __cplusplus >= 201402L) || (defined(_HAS_CXX14) && _HAS_CXX14 == 1)
    #define JSON_HAS_CPP_14
#endif

#ifdef JSON_HAS_CPP_17
    #if __has_include(<optional>)
        #include <optional>
    #elif __has_include(<experimental/optional>)
        #include <experimental/optional>
    #endif
#endif

#if defined(JSON_HAS_CPP_17)
    #include <string_view>
#endif

TEST_CASE("value conversion")
{
    SECTION("get an object (explicit)")
    {
        const json::object_t o_reference = {{"object", json::object()},
            {"array", {1, 2, 3, 4}},
            {"number", 42},
            {"boolean", false},
            {"null", nullptr},
            {"string", "Hello world"}
        };
        json j(o_reference);

        SECTION("json::object_t")
        {
            json::object_t const o = j.get<json::object_t>();
            CHECK(json(o) == j);
        }

        SECTION("std::map<json::string_t, json>")
        {
            const std::map<json::string_t, json> o =
                j.get<std::map<json::string_t, json>>();
            CHECK(json(o) == j);
        }

        SECTION("std::multimap<json::string_t, json>")
        {
            const std::multimap<json::string_t, json> o =
                j.get<std::multimap<json::string_t, json>>();
            CHECK(json(o) == j);
        }

        SECTION("std::unordered_map<json::string_t, json>")
        {
            const std::unordered_map<json::string_t, json> o =
                j.get<std::unordered_map<json::string_t, json>>();
            CHECK(json(o) == j);
        }

        SECTION("std::unordered_multimap<json::string_t, json>")
        {
            const std::unordered_multimap<json::string_t, json> o =
                j.get<std::unordered_multimap<json::string_t, json>>();
            CHECK(json(o) == j);
        }

        SECTION("exception in case of a non-object type")
        {
            CHECK_THROWS_WITH_AS(
                json(json::value_t::null).get<json::object_t>(),
                "[json.exception.type_error.302] type must be object, but is null", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::array).get<json::object_t>(),
                "[json.exception.type_error.302] type must be object, but is array", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::string).get<json::object_t>(),
                "[json.exception.type_error.302] type must be object, but is string", json::type_error&);
            CHECK_THROWS_WITH_AS(json(json::value_t::boolean).get<json::object_t>(),
                                 "[json.exception.type_error.302] type must be object, "
                                 "but is boolean", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::number_integer).get<json::object_t>(),
                "[json.exception.type_error.302] type must be object, but is number", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::number_unsigned).get<json::object_t>(),
                "[json.exception.type_error.302] type must be object, but is number", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::number_float).get<json::object_t>(),
                "[json.exception.type_error.302] type must be object, but is number", json::type_error&);
        }
    }

    SECTION("get an object (explicit, get_to)")
    {
        const json::object_t o_reference = {{"object", json::object()},
            {"array", {1, 2, 3, 4}},
            {"number", 42},
            {"boolean", false},
            {"null", nullptr},
            {"string", "Hello world"}
        };
        json j(o_reference);

        SECTION("json::object_t")
        {
            json::object_t o = {{"previous", "value"}};
            j.get_to(o);
            CHECK(json(o) == j);
        }

        SECTION("std::map<json::string_t, json>")
        {
            std::map<json::string_t, json> o{{"previous", "value"}};
            j.get_to(o);
            CHECK(json(o) == j);
        }

        SECTION("std::multimap<json::string_t, json>")
        {
            std::multimap<json::string_t, json> o{{"previous", "value"}};
            j.get_to(o);
            CHECK(json(o) == j);
        }

        SECTION("std::unordered_map<json::string_t, json>")
        {
            std::unordered_map<json::string_t, json> o{{"previous", "value"}};
            j.get_to(o);
            CHECK(json(o) == j);
        }

        SECTION("std::unordered_multimap<json::string_t, json>")
        {
            std::unordered_multimap<json::string_t, json> o{{"previous", "value"}};
            j.get_to(o);
            CHECK(json(o) == j);
        }
    }

#if JSON_USE_IMPLICIT_CONVERSIONS

    SECTION("get an object (implicit)")
    {
        const json::object_t o_reference = {{"object", json::object()},
            {"array", {1, 2, 3, 4}},
            {"number", 42},
            {"boolean", false},
            {"null", nullptr},
            {"string", "Hello world"}
        };
        json j(o_reference);

        SECTION("json::object_t")
        {
            const json::object_t o = j;
            CHECK(json(o) == j);
        }

        SECTION("std::map<json::string_t, json>")
        {
            const std::map<json::string_t, json> o = j;
            CHECK(json(o) == j);
        }

        SECTION("std::multimap<json::string_t, json>")
        {
            const std::multimap<json::string_t, json> o = j;
            CHECK(json(o) == j);
        }

        SECTION("std::unordered_map<json::string_t, json>")
        {
            const std::unordered_map<json::string_t, json> o = j;
            CHECK(json(o) == j);
        }

        SECTION("std::unordered_multimap<json::string_t, json>")
        {
            const std::unordered_multimap<json::string_t, json> o = j;
            CHECK(json(o) == j);
        }
    }
#endif

    SECTION("get an array (explicit)")
    {
        const json::array_t a_reference{json(1),     json(1u),       json(2.2),
                                        json(false), json("string"), json()};
        json j(a_reference);

        SECTION("json::array_t")
        {
            const json::array_t a = j.get<json::array_t>();
            CHECK(json(a) == j);
        }

        SECTION("std::list<json>")
        {
            const std::list<json> a = j.get<std::list<json>>();
            CHECK(json(a) == j);
        }

        SECTION("std::forward_list<json>")
        {
            const std::forward_list<json> a = j.get<std::forward_list<json>>();
            CHECK(json(a) == j);

            CHECK_THROWS_WITH_AS(
                json(json::value_t::null).get<std::forward_list<json>>(),
                "[json.exception.type_error.302] type must be array, but is null", json::type_error&);
        }

        SECTION("std::vector<json>")
        {
            const std::vector<json> a = j.get<std::vector<json>>();
            CHECK(json(a) == j);

            CHECK_THROWS_WITH_AS(
                json(json::value_t::null).get<std::vector<json>>(),
                "[json.exception.type_error.302] type must be array, but is null", json::type_error&);

#if !defined(JSON_NOEXCEPTION)
            SECTION("reserve is called on containers that supports it")
            {
                // make sure all values are properly copied
                const json j2({1, 2, 3, 4, 5, 6, 7, 8, 9, 10});
                auto v2 = j2.get<std::vector<int>>();
                CHECK(v2.size() == 10);
            }
#endif
        }

        SECTION("built-in arrays")
        {
            const char str[] = "a string"; // NOLINT(misc-const-correctness,cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
            const int nbs[] = {0, 1, 2}; // NOLINT(misc-const-correctness,cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)

            const json j2 = nbs;
            const json j3 = str;

            auto v = j2.get<std::vector<int>>();
            auto s = j3.get<std::string>();
            CHECK(std::equal(v.begin(), v.end(), std::begin(nbs)));
            CHECK(s == str);
        }

        SECTION("std::deque<json>")
        {
            const std::deque<json> a = j.get<std::deque<json>>();
            CHECK(json(a) == j);
        }

        SECTION("exception in case of a non-array type")
        {
            CHECK_THROWS_WITH_AS(
                json(json::value_t::object).get<std::vector<int>>(),
                "[json.exception.type_error.302] type must be array, but is object", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::null).get<json::array_t>(),
                "[json.exception.type_error.302] type must be array, but is null", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::object).get<json::array_t>(),
                "[json.exception.type_error.302] type must be array, but is object", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::string).get<json::array_t>(),
                "[json.exception.type_error.302] type must be array, but is string", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::boolean).get<json::array_t>(),
                "[json.exception.type_error.302] type must be array, but is boolean", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::number_integer).get<json::array_t>(),
                "[json.exception.type_error.302] type must be array, but is number", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::number_unsigned).get<json::array_t>(),
                "[json.exception.type_error.302] type must be array, but is number", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::number_float).get<json::array_t>(),
                "[json.exception.type_error.302] type must be array, but is number", json::type_error&);
        }
    }

    SECTION("get an array (explicit, get_to)")
    {
        const json::array_t a_reference{json(1),     json(1u),       json(2.2),
                                        json(false), json("string"), json()};
        json j(a_reference);

        SECTION("json::array_t")
        {
            json::array_t a{"previous", "value"};
            j.get_to(a);
            CHECK(json(a) == j);
        }

        SECTION("std::valarray<json>")
        {
            std::valarray<json> a{"previous", "value"};
            j.get_to(a);
            CHECK(json(a) == j);
        }

        SECTION("std::list<json>")
        {
            std::list<json> a{"previous", "value"};
            j.get_to(a);
            CHECK(json(a) == j);
        }

        SECTION("std::forward_list<json>")
        {
            std::forward_list<json> a{"previous", "value"};
            j.get_to(a);
            CHECK(json(a) == j);
        }

        SECTION("std::vector<json>")
        {
            std::vector<json> a{"previous", "value"};
            j.get_to(a);
            CHECK(json(a) == j);
        }

        SECTION("built-in arrays")
        {
            const int nbs[] = {0, 1, 2}; // NOLINT(misc-const-correctness,cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
            int nbs2[] = {0, 0, 0}; // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)

            const json j2 = nbs;
            j2.get_to(nbs2);
            CHECK(std::equal(std::begin(nbs), std::end(nbs), std::begin(nbs2)));
        }

        SECTION("built-in arrays: 2D")
        {
            const int nbs[][3] = {{0, 1, 2}, {3, 4, 5}}; // NOLINT(misc-const-correctness,cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
            int nbs2[][3] = {{0, 0, 0}, {0, 0, 0}}; // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)

            const json j2 = nbs;
            j2.get_to(nbs2);
            CHECK(std::equal(std::begin(nbs[0]), std::end(nbs[1]), std::begin(nbs2[0])));
        }

        SECTION("built-in arrays: 3D")
        {
            // NOLINTBEGIN(misc-const-correctness,cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
            const int nbs[][2][3] = {\
                {{0, 1, 2}, {3, 4, 5}}, \
                {{10, 11, 12}, {13, 14, 15}}\
            };
            int nbs2[][2][3] = {\
                {{0, 0, 0}, {0, 0, 0}}, \
                {{0, 0, 0}, {0, 0, 0}}\
            };
            // NOLINTEND(misc-const-correctness,cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)

            const json j2 = nbs;
            j2.get_to(nbs2);
            CHECK(std::equal(std::begin(nbs[0][0]), std::end(nbs[1][1]), std::begin(nbs2[0][0])));
        }

        SECTION("built-in arrays: 4D")
        {
            // NOLINTBEGIN(misc-const-correctness,cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
            const int nbs[][2][2][3] = {\
                {
                    \
                    {{0, 1, 2}, {3, 4, 5}}, \
                    {{10, 11, 12}, {13, 14, 15}}\
                }, \
                {
                    \
                    {{20, 21, 22}, {23, 24, 25}}, \
                    {{30, 31, 32}, {33, 34, 35}}\
                }\
            };
            int nbs2[][2][2][3] = {\
                {
                    \
                    {{0, 0, 0}, {0, 0, 0}}, \
                    {{0, 0, 0}, {0, 0, 0}}\
                }, \
                {
                    \
                    {{0, 0, 0}, {0, 0, 0}}, \
                    {{0, 0, 0}, {0, 0, 0}}\
                }\
            };
            // NOLINTEND(misc-const-correctness,cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)

            const json j2 = nbs;
            j2.get_to(nbs2);
            CHECK(std::equal(std::begin(nbs[0][0][0]), std::end(nbs[1][1][1]), std::begin(nbs2[0][0][0])));
        }

        SECTION("std::deque<json>")
        {
            std::deque<json> a{"previous", "value"};
            j.get_to(a);
            CHECK(json(a) == j);
        }
    }

#if JSON_USE_IMPLICIT_CONVERSIONS
    SECTION("get an array (implicit)")
    {
        const json::array_t a_reference{json(1),     json(1u),       json(2.2),
                                        json(false), json("string"), json()};
        json j(a_reference);

        SECTION("json::array_t")
        {
            const json::array_t a = j;
            CHECK(json(a) == j);
        }

        SECTION("std::list<json>")
        {
            const std::list<json> a = j;
            CHECK(json(a) == j);
        }

        SECTION("std::forward_list<json>")
        {
            const std::forward_list<json> a = j;
            CHECK(json(a) == j);
        }

        SECTION("std::vector<json>")
        {
            const std::vector<json> a = j;
            CHECK(json(a) == j);
        }

        SECTION("std::deque<json>")
        {
            const std::deque<json> a = j;
            CHECK(json(a) == j);
        }
    }
#endif

    SECTION("get a string (explicit)")
    {
        const json::string_t s_reference{"Hello world"};
        json j(s_reference);

        SECTION("string_t")
        {
            const json::string_t s = j.get<json::string_t>();
            CHECK(json(s) == j);
        }

        SECTION("std::string")
        {
            const std::string s = j.get<std::string>();
            CHECK(json(s) == j);
        }
#if defined(JSON_HAS_CPP_17)
        SECTION("std::string_view")
        {
            std::string_view const s = j.get<std::string_view>();
            CHECK(json(s) == j);
        }
#endif

        SECTION("exception in case of a non-string type")
        {
            CHECK_THROWS_WITH_AS(
                json(json::value_t::null).get<json::string_t>(),
                "[json.exception.type_error.302] type must be string, but is null", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::object).get<json::string_t>(),
                "[json.exception.type_error.302] type must be string, but is object", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::array).get<json::string_t>(),
                "[json.exception.type_error.302] type must be string, but is array", json::type_error&);
            CHECK_THROWS_WITH_AS(json(json::value_t::boolean).get<json::string_t>(),
                                 "[json.exception.type_error.302] type must be string, "
                                 "but is boolean", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::number_integer).get<json::string_t>(),
                "[json.exception.type_error.302] type must be string, but is number", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::number_unsigned).get<json::string_t>(),
                "[json.exception.type_error.302] type must be string, but is number", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::number_float).get<json::string_t>(),
                "[json.exception.type_error.302] type must be string, but is number", json::type_error&);
        }

#if defined(JSON_HAS_CPP_17)
        SECTION("exception in case of a non-string type using string_view")
        {
            CHECK_THROWS_WITH_AS(json(json::value_t::null).get<std::string_view>(),
                                 "[json.exception.type_error.302] type must be string, but is null", json::type_error&);
            CHECK_THROWS_WITH_AS(json(json::value_t::object).get<std::string_view>(),
                                 "[json.exception.type_error.302] type must be string, but is object", json::type_error&);
            CHECK_THROWS_WITH_AS(json(json::value_t::array).get<std::string_view>(),
                                 "[json.exception.type_error.302] type must be string, but is array", json::type_error&);
            CHECK_THROWS_WITH_AS(json(json::value_t::boolean).get<std::string_view>(),
                                 "[json.exception.type_error.302] type must be string, but is boolean", json::type_error&);
            CHECK_THROWS_WITH_AS(json(json::value_t::number_integer).get<std::string_view>(),
                                 "[json.exception.type_error.302] type must be string, but is number", json::type_error&);
            CHECK_THROWS_WITH_AS(json(json::value_t::number_unsigned).get<std::string_view>(),
                                 "[json.exception.type_error.302] type must be string, but is number", json::type_error&);
            CHECK_THROWS_WITH_AS(json(json::value_t::number_float).get<std::string_view>(),
                                 "[json.exception.type_error.302] type must be string, but is number", json::type_error&);
        }
#endif
    }

    SECTION("get a string (explicit, get_to)")
    {
        const json::string_t s_reference{"Hello world"};
        json j(s_reference);

        SECTION("string_t")
        {
            json::string_t s = "previous value";
            j.get_to(s);
            CHECK(json(s) == j);
        }

        SECTION("std::string")
        {
            std::string s = "previous value";
            j.get_to(s);
            CHECK(json(s) == j);
        }
#if defined(JSON_HAS_CPP_17)
        SECTION("std::string_view")
        {
            std::string const s = "previous value";
            std::string_view sv = s;
            j.get_to(sv);
            CHECK(json(sv) == j);
        }
#endif
    }

    SECTION("get null (explicit)")
    {
        std::nullptr_t n = nullptr;
        const json j(n);

        auto n2 = j.get<std::nullptr_t>();
        CHECK(n2 == n);

        CHECK_THROWS_WITH_AS(json(json::value_t::string).get<std::nullptr_t>(),
                             "[json.exception.type_error.302] type must be null, but is string", json::type_error&);
        CHECK_THROWS_WITH_AS(json(json::value_t::object).get<std::nullptr_t>(),
                             "[json.exception.type_error.302] type must be null, but is object", json::type_error&);
        CHECK_THROWS_WITH_AS(json(json::value_t::array).get<std::nullptr_t>(),
                             "[json.exception.type_error.302] type must be null, but is array", json::type_error&);
        CHECK_THROWS_WITH_AS(json(json::value_t::boolean).get<std::nullptr_t>(),
                             "[json.exception.type_error.302] type must be null, but is boolean", json::type_error&);
        CHECK_THROWS_WITH_AS(json(json::value_t::number_integer).get<std::nullptr_t>(),
                             "[json.exception.type_error.302] type must be null, but is number", json::type_error&);
        CHECK_THROWS_WITH_AS(json(json::value_t::number_unsigned).get<std::nullptr_t>(),
                             "[json.exception.type_error.302] type must be null, but is number", json::type_error&);
        CHECK_THROWS_WITH_AS(json(json::value_t::number_float).get<std::nullptr_t>(),
                             "[json.exception.type_error.302] type must be null, but is number", json::type_error&);
    }

#if JSON_USE_IMPLICIT_CONVERSIONS
    SECTION("get a string (implicit)")
    {
        const json::string_t s_reference{"Hello world"};
        json j(s_reference);

        SECTION("string_t")
        {
            const json::string_t s = j;
            CHECK(json(s) == j);
        }

#if defined(JSON_HAS_CPP_17)
        SECTION("std::string_view")
        {
            std::string_view const s = j.get<std::string_view>();
            CHECK(json(s) == j);
        }
#endif

        SECTION("std::string")
        {
            const std::string s = j;
            CHECK(json(s) == j);
        }
    }
#endif

    SECTION("get a boolean (explicit)")
    {
        const json::boolean_t b_reference{true};
        json j(b_reference);

        SECTION("boolean_t")
        {
            auto b = j.get<json::boolean_t>();
            CHECK(json(b) == j);
        }

        SECTION("uint8_t")
        {
            auto n = j.get<uint8_t>();
            CHECK(n == 1);
        }

        SECTION("bool")
        {
            const bool b = j.get<bool>();
            CHECK(json(b) == j);
        }

        SECTION("exception in case of a non-number type")
        {
            CHECK_THROWS_AS(json(json::value_t::string).get<uint8_t>(),
                            json::type_error&);

            CHECK_THROWS_WITH_AS(
                json(json::value_t::null).get<json::boolean_t>(),
                "[json.exception.type_error.302] type must be boolean, but is null", json::type_error&);
            CHECK_THROWS_WITH_AS(json(json::value_t::object).get<json::boolean_t>(),
                                 "[json.exception.type_error.302] type must be boolean, "
                                 "but is object", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::array).get<json::boolean_t>(),
                "[json.exception.type_error.302] type must be boolean, but is array", json::type_error&);
            CHECK_THROWS_WITH_AS(json(json::value_t::string).get<json::boolean_t>(),
                                 "[json.exception.type_error.302] type must be boolean, "
                                 "but is string", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::number_integer).get<json::boolean_t>(),
                "[json.exception.type_error.302] type must be boolean, but is "
                "number", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::number_unsigned).get<json::boolean_t>(),
                "[json.exception.type_error.302] type must be boolean, but is "
                "number", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::number_float).get<json::boolean_t>(),
                "[json.exception.type_error.302] type must be boolean, but is "
                "number", json::type_error&);
        }
    }

#if JSON_USE_IMPLICIT_CONVERSIONS
    SECTION("get a boolean (implicit)")
    {
        const json::boolean_t b_reference{true};
        json j(b_reference);

        SECTION("boolean_t")
        {
            const json::boolean_t b = j;
            CHECK(json(b) == j);
        }

        SECTION("bool")
        {
            const bool b = j;
            CHECK(json(b) == j);
        }
    }
#endif

    SECTION("get an integer number (explicit)")
    {
        const json::number_integer_t n_reference{42};
        json j(n_reference);
        const json::number_unsigned_t n_unsigned_reference{42u};
        json j_unsigned(n_unsigned_reference);

        SECTION("number_integer_t")
        {
            auto n = j.get<json::number_integer_t>();
            CHECK(json(n) == j);
        }

        SECTION("number_unsigned_t")
        {
            auto n = j_unsigned.get<json::number_unsigned_t>();
            CHECK(json(n) == j_unsigned);
        }

        SECTION("short")
        {
            auto n = j.get<short>();
            CHECK(json(n) == j);
        }

        SECTION("unsigned short")
        {
            auto n = j.get<unsigned short>();
            CHECK(json(n) == j);
        }

        SECTION("int")
        {
            const int n = j.get<int>();
            CHECK(json(n) == j);
        }

        SECTION("unsigned int")
        {
            auto n = j.get<unsigned int>();
            CHECK(json(n) == j);
        }

        SECTION("long")
        {
            const long n = j.get<long>();
            CHECK(json(n) == j);
        }

        SECTION("unsigned long")
        {
            auto n = j.get<unsigned long>();
            CHECK(json(n) == j);
        }

        SECTION("long long")
        {
            auto n = j.get<long long>();
            CHECK(json(n) == j);
        }

        SECTION("unsigned long long")
        {
            auto n = j.get<unsigned long long>();
            CHECK(json(n) == j);
        }

        SECTION("int8_t")
        {
            auto n = j.get<int8_t>();
            CHECK(json(n) == j);
        }

        SECTION("int16_t")
        {
            auto n = j.get<int16_t>();
            CHECK(json(n) == j);
        }

        SECTION("int32_t")
        {
            auto n = j.get<int32_t>();
            CHECK(json(n) == j);
        }

        SECTION("int64_t")
        {
            auto n = j.get<int64_t>();
            CHECK(json(n) == j);
        }

        SECTION("int8_fast_t")
        {
            auto n = j.get<int_fast8_t>();
            CHECK(json(n) == j);
        }

        SECTION("int16_fast_t")
        {
            auto n = j.get<int_fast16_t>();
            CHECK(json(n) == j);
        }

        SECTION("int32_fast_t")
        {
            auto n = j.get<int_fast32_t>();
            CHECK(json(n) == j);
        }

        SECTION("int64_fast_t")
        {
            auto n = j.get<int_fast64_t>();
            CHECK(json(n) == j);
        }

        SECTION("int8_least_t")
        {
            auto n = j.get<int_least8_t>();
            CHECK(json(n) == j);
        }

        SECTION("int16_least_t")
        {
            auto n = j.get<int_least16_t>();
            CHECK(json(n) == j);
        }

        SECTION("int32_least_t")
        {
            auto n = j.get<int_least32_t>();
            CHECK(json(n) == j);
        }

        SECTION("int64_least_t")
        {
            auto n = j.get<int_least64_t>();
            CHECK(json(n) == j);
        }

        SECTION("uint8_t")
        {
            auto n = j.get<uint8_t>();
            CHECK(json(n) == j);
        }

        SECTION("uint16_t")
        {
            auto n = j.get<uint16_t>();
            CHECK(json(n) == j);
        }

        SECTION("uint32_t")
        {
            auto n = j.get<uint32_t>();
            CHECK(json(n) == j);
        }

        SECTION("uint64_t")
        {
            auto n = j.get<uint64_t>();
            CHECK(json(n) == j);
        }

        SECTION("uint8_fast_t")
        {
            auto n = j.get<uint_fast8_t>();
            CHECK(json(n) == j);
        }

        SECTION("uint16_fast_t")
        {
            auto n = j.get<uint_fast16_t>();
            CHECK(json(n) == j);
        }

        SECTION("uint32_fast_t")
        {
            auto n = j.get<uint_fast32_t>();
            CHECK(json(n) == j);
        }

        SECTION("uint64_fast_t")
        {
            auto n = j.get<uint_fast64_t>();
            CHECK(json(n) == j);
        }

        SECTION("uint8_least_t")
        {
            auto n = j.get<uint_least8_t>();
            CHECK(json(n) == j);
        }

        SECTION("uint16_least_t")
        {
            auto n = j.get<uint_least16_t>();
            CHECK(json(n) == j);
        }

        SECTION("uint32_least_t")
        {
            auto n = j.get<uint_least32_t>();
            CHECK(json(n) == j);
        }

        SECTION("uint64_least_t")
        {
            auto n = j.get<uint_least64_t>();
            CHECK(json(n) == j);
        }

        SECTION("exception in case of a non-number type")
        {
            CHECK_THROWS_WITH_AS(
                json(json::value_t::null).get<json::number_integer_t>(),
                "[json.exception.type_error.302] type must be number, but is null", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::object).get<json::number_integer_t>(),
                "[json.exception.type_error.302] type must be number, but is object", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::array).get<json::number_integer_t>(),
                "[json.exception.type_error.302] type must be number, but is array", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::string).get<json::number_integer_t>(),
                "[json.exception.type_error.302] type must be number, but is string", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::boolean).get<json::number_integer_t>(),
                "[json.exception.type_error.302] type must be number, but is "
                "boolean", json::type_error&);

            CHECK_NOTHROW(
                json(json::value_t::number_float).get<json::number_integer_t>());
            CHECK_NOTHROW(
                json(json::value_t::number_float).get<json::number_unsigned_t>());
        }
    }

#if JSON_USE_IMPLICIT_CONVERSIONS
    SECTION("get an integer number (implicit)")
    {
        json::number_integer_t const n_reference{42};
        json j(n_reference);
        json::number_unsigned_t const n_unsigned_reference{42u};
        json j_unsigned(n_unsigned_reference);

        SECTION("number_integer_t")
        {
            auto n = j.get<json::number_integer_t>();
            CHECK(json(n) == j);
        }

        SECTION("number_unsigned_t")
        {
            auto n = j_unsigned.get<json::number_unsigned_t>();
            CHECK(json(n) == j_unsigned);
        }

        SECTION("short")
        {
            short const n = j;
            CHECK(json(n) == j);
        }

        SECTION("unsigned short")
        {
            unsigned short const n = j_unsigned;
            CHECK(json(n) == j_unsigned);
        }

        SECTION("int")
        {
            int const n = j;
            CHECK(json(n) == j);
        }

        SECTION("unsigned int")
        {
            unsigned int const n = j_unsigned;
            CHECK(json(n) == j_unsigned);
        }

        SECTION("long")
        {
            long const n = j;
            CHECK(json(n) == j);
        }

        SECTION("unsigned long")
        {
            unsigned long const n = j_unsigned;
            CHECK(json(n) == j_unsigned);
        }

        SECTION("long long")
        {
            long long const n = j;
            CHECK(json(n) == j);
        }

        SECTION("unsigned long long")
        {
            unsigned long long const n = j_unsigned;
            CHECK(json(n) == j_unsigned);
        }

        SECTION("int8_t")
        {
            int8_t const n = j;
            CHECK(json(n) == j);
        }

        SECTION("int16_t")
        {
            int16_t const n = j;
            CHECK(json(n) == j);
        }

        SECTION("int32_t")
        {
            int32_t const n = j;
            CHECK(json(n) == j);
        }

        SECTION("int64_t")
        {
            int64_t const n = j;
            CHECK(json(n) == j);
        }

        SECTION("int8_fast_t")
        {
            int_fast8_t const n = j;
            CHECK(json(n) == j);
        }

        SECTION("int16_fast_t")
        {
            int_fast16_t const n = j;
            CHECK(json(n) == j);
        }

        SECTION("int32_fast_t")
        {
            int_fast32_t const n = j;
            CHECK(json(n) == j);
        }

        SECTION("int64_fast_t")
        {
            int_fast64_t const n = j;
            CHECK(json(n) == j);
        }

        SECTION("int8_least_t")
        {
            int_least8_t const n = j;
            CHECK(json(n) == j);
        }

        SECTION("int16_least_t")
        {
            int_least16_t const n = j;
            CHECK(json(n) == j);
        }

        SECTION("int32_least_t")
        {
            int_least32_t const n = j;
            CHECK(json(n) == j);
        }

        SECTION("int64_least_t")
        {
            int_least64_t const n = j;
            CHECK(json(n) == j);
        }

        SECTION("uint8_t")
        {
            uint8_t const n = j_unsigned;
            CHECK(json(n) == j_unsigned);
        }

        SECTION("uint16_t")
        {
            uint16_t const n = j_unsigned;
            CHECK(json(n) == j_unsigned);
        }

        SECTION("uint32_t")
        {
            uint32_t const n = j_unsigned;
            CHECK(json(n) == j_unsigned);
        }

        SECTION("uint64_t")
        {
            uint64_t const n = j_unsigned;
            CHECK(json(n) == j_unsigned);
        }

        SECTION("uint8_fast_t")
        {
            uint_fast8_t const n = j_unsigned;
            CHECK(json(n) == j_unsigned);
        }

        SECTION("uint16_fast_t")
        {
            uint_fast16_t const n = j_unsigned;
            CHECK(json(n) == j_unsigned);
        }

        SECTION("uint32_fast_t")
        {
            uint_fast32_t const n = j_unsigned;
            CHECK(json(n) == j_unsigned);
        }

        SECTION("uint64_fast_t")
        {
            uint_fast64_t const n = j_unsigned;
            CHECK(json(n) == j_unsigned);
        }

        SECTION("uint8_least_t")
        {
            uint_least8_t const n = j_unsigned;
            CHECK(json(n) == j_unsigned);
        }

        SECTION("uint16_least_t")
        {
            uint_least16_t const n = j_unsigned;
            CHECK(json(n) == j_unsigned);
        }

        SECTION("uint32_least_t")
        {
            uint_least32_t const n = j_unsigned;
            CHECK(json(n) == j_unsigned);
        }

        SECTION("uint64_least_t")
        {
            uint_least64_t const n = j_unsigned;
            CHECK(json(n) == j_unsigned);
        }
    }
#endif

    SECTION("get a floating-point number (explicit)")
    {
        json::number_float_t const n_reference{42.23};
        json const j(n_reference);

        SECTION("number_float_t")
        {
            auto n = j.get<json::number_float_t>();
            CHECK(json(n).m_data.m_value.number_float == Approx(j.m_data.m_value.number_float));
        }

        SECTION("float")
        {
            auto n = j.get<float>();
            CHECK(json(n).m_data.m_value.number_float == Approx(j.m_data.m_value.number_float));
        }

        SECTION("double")
        {
            auto n = j.get<double>();
            CHECK(json(n).m_data.m_value.number_float == Approx(j.m_data.m_value.number_float));
        }

        SECTION("exception in case of a non-string type")
        {
            CHECK_THROWS_WITH_AS(
                json(json::value_t::null).get<json::number_float_t>(),
                "[json.exception.type_error.302] type must be number, but is null", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::object).get<json::number_float_t>(),
                "[json.exception.type_error.302] type must be number, but is object", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::array).get<json::number_float_t>(),
                "[json.exception.type_error.302] type must be number, but is array", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::string).get<json::number_float_t>(),
                "[json.exception.type_error.302] type must be number, but is string", json::type_error&);
            CHECK_THROWS_WITH_AS(
                json(json::value_t::boolean).get<json::number_float_t>(),
                "[json.exception.type_error.302] type must be number, but is "
                "boolean", json::type_error&);

            CHECK_NOTHROW(
                json(json::value_t::number_integer).get<json::number_float_t>());
            CHECK_NOTHROW(
                json(json::value_t::number_unsigned).get<json::number_float_t>());
        }
    }

#if JSON_USE_IMPLICIT_CONVERSIONS
    SECTION("get a floating-point number (implicit)")
    {
        json::number_float_t const n_reference{42.23};
        json const j(n_reference);

        SECTION("number_float_t")
        {
            json::number_float_t const n = j;
            CHECK(json(n).m_data.m_value.number_float == Approx(j.m_data.m_value.number_float));
        }

        SECTION("float")
        {
            float const n = j;
            CHECK(json(n).m_data.m_value.number_float == Approx(j.m_data.m_value.number_float));
        }

        SECTION("double")
        {
            double const n = j;
            CHECK(json(n).m_data.m_value.number_float == Approx(j.m_data.m_value.number_float));
        }
    }
#endif

    SECTION("get a binary value (explicit)")
    {
        json::binary_t const n_reference{{1, 2, 3}};
        json j(n_reference);

        SECTION("binary_t")
        {
            json::binary_t const b = j.get<json::binary_t>();
            CHECK(*json(b).m_data.m_value.binary == *j.m_data.m_value.binary);
        }

        SECTION("get_binary()")
        {
            SECTION("non-const")
            {
                auto& b = j.get_binary();
                CHECK(*json(b).m_data.m_value.binary == *j.m_data.m_value.binary);
            }

            SECTION("non-const")
            {
                const json j_const = j; // NOLINT(performance-unnecessary-copy-initialization)
                const auto& b = j_const.get_binary();
                CHECK(*json(b).m_data.m_value.binary == *j.m_data.m_value.binary);
            }
        }

        SECTION("exception in case of a non-string type")
        {
            json j_null(json::value_t::null);
            json j_object(json::value_t::object);
            json j_array(json::value_t::array);
            json j_string(json::value_t::string);
            json j_boolean(json::value_t::boolean);
            const json j_null_const(json::value_t::null);
            const json j_object_const(json::value_t::object);
            const json j_array_const(json::value_t::array);
            const json j_string_const(json::value_t::string);
            const json j_boolean_const(json::value_t::boolean);

            CHECK_THROWS_WITH_AS(j_null.get<json::binary_t>(),
                                 "[json.exception.type_error.302] type must be binary, but is null",
                                 json::type_error&);
            CHECK_THROWS_WITH_AS(j_object.get<json::binary_t>(),
                                 "[json.exception.type_error.302] type must be binary, but is object",
                                 json::type_error&);
            CHECK_THROWS_WITH_AS(j_array.get<json::binary_t>(),
                                 "[json.exception.type_error.302] type must be binary, but is array",
                                 json::type_error&);
            CHECK_THROWS_WITH_AS(j_string.get<json::binary_t>(),
                                 "[json.exception.type_error.302] type must be binary, but is string",
                                 json::type_error&);
            CHECK_THROWS_WITH_AS(j_boolean.get<json::binary_t>(),
                                 "[json.exception.type_error.302] type must be binary, but is boolean",
                                 json::type_error&);

            CHECK_THROWS_WITH_AS(j_null_const.get<json::binary_t>(),
                                 "[json.exception.type_error.302] type must be binary, but is null",
                                 json::type_error&);
            CHECK_THROWS_WITH_AS(j_object_const.get<json::binary_t>(),
                                 "[json.exception.type_error.302] type must be binary, but is object",
                                 json::type_error&);
            CHECK_THROWS_WITH_AS(j_array_const.get<json::binary_t>(),
                                 "[json.exception.type_error.302] type must be binary, but is array",
                                 json::type_error&);
            CHECK_THROWS_WITH_AS(j_string_const.get<json::binary_t>(),
                                 "[json.exception.type_error.302] type must be binary, but is string",
                                 json::type_error&);
            CHECK_THROWS_WITH_AS(j_boolean_const.get<json::binary_t>(),
                                 "[json.exception.type_error.302] type must be binary, but is boolean",
                                 json::type_error&);

            CHECK_THROWS_WITH_AS(j_null.get_binary(),
                                 "[json.exception.type_error.302] type must be binary, but is null",
                                 json::type_error&);
            CHECK_THROWS_WITH_AS(j_object.get_binary(),
                                 "[json.exception.type_error.302] type must be binary, but is object",
                                 json::type_error&);
            CHECK_THROWS_WITH_AS(j_array.get_binary(),
                                 "[json.exception.type_error.302] type must be binary, but is array",
                                 json::type_error&);
            CHECK_THROWS_WITH_AS(j_string.get_binary(),
                                 "[json.exception.type_error.302] type must be binary, but is string",
                                 json::type_error&);
            CHECK_THROWS_WITH_AS(j_boolean.get_binary(),
                                 "[json.exception.type_error.302] type must be binary, but is boolean",
                                 json::type_error&);

            CHECK_THROWS_WITH_AS(j_null_const.get_binary(),
                                 "[json.exception.type_error.302] type must be binary, but is null",
                                 json::type_error&);
            CHECK_THROWS_WITH_AS(j_object_const.get_binary(),
                                 "[json.exception.type_error.302] type must be binary, but is object",
                                 json::type_error&);
            CHECK_THROWS_WITH_AS(j_array_const.get_binary(),
                                 "[json.exception.type_error.302] type must be binary, but is array",
                                 json::type_error&);
            CHECK_THROWS_WITH_AS(j_string_const.get_binary(),
                                 "[json.exception.type_error.302] type must be binary, but is string",
                                 json::type_error&);
            CHECK_THROWS_WITH_AS(j_boolean_const.get_binary(),
                                 "[json.exception.type_error.302] type must be binary, but is boolean",
                                 json::type_error&);
        }
    }

#if JSON_USE_IMPLICIT_CONVERSIONS
    SECTION("get a binary value (implicit)")
    {
        json::binary_t const n_reference{{1, 2, 3}};
        json const j(n_reference);

        SECTION("binary_t")
        {
            json::binary_t const b = j;
            CHECK(*json(b).m_data.m_value.binary == *j.m_data.m_value.binary);
        }
    }
#endif

#ifndef SKIP_TESTS_FOR_ENUM_SERIALIZATION
    SECTION("get an enum")
    {
        enum c_enum { value_1, value_2 }; // NOLINT(cppcoreguidelines-use-enum-class)
        enum class cpp_enum { value_1, value_2 };

        CHECK(json(value_1).get<c_enum>() == value_1);
        CHECK(json(cpp_enum::value_1).get<cpp_enum>() == cpp_enum::value_1);
    }

    SECTION("get an enum with underlying type bool (#5671)")
    {
        enum class bool_enum : bool { off, on };

        CHECK(json(bool_enum::off).get<bool_enum>() == bool_enum::off);
        CHECK(json(bool_enum::on).get<bool_enum>() == bool_enum::on);
    }
#endif

    SECTION("more involved conversions")
    {
        SECTION("object-like STL containers")
        {
            json const j1 = {{"one", 1}, {"two", 2}, {"three", 3}};
            json const j2 = {{"one", 1u}, {"two", 2u}, {"three", 3u}};
            json const j3 = {{"one", 1.1}, {"two", 2.2}, {"three", 3.3}};
            json const j4 = {{"one", true}, {"two", false}, {"three", true}};
            json const j5 = {{"one", "eins"}, {"two", "zwei"}, {"three", "drei"}};

            SECTION("std::map")
            {
                CHECK(j1.get<std::map<std::string, int>>() == (std::map<std::string, int> {{"one", 1}, {"two", 2}, {"three", 3}}));
                CHECK(j2.get<std::map<std::string, unsigned int>>() == (std::map<std::string, unsigned int> {{"one", 1u}, {"two", 2u}, {"three", 3u}}));
                CHECK(j3.get<std::map<std::string, double>>() == (std::map<std::string, double> {{"one", 1.1}, {"two", 2.2}, {"three", 3.3}}));
                CHECK(j4.get<std::map<std::string, bool>>() == (std::map<std::string, bool> {{"one", true}, {"two", false}, {"three", true}}));
                CHECK(j5.get<std::map<std::string, std::string>>() == (std::map<std::string, std::string> {{"one", "eins"}, {"two", "zwei"}, {"three", "drei"}}));
            }

            SECTION("std::unordered_map")
            {
                CHECK(j1.get<std::unordered_map<std::string, int>>() == (std::unordered_map<std::string, int> {{"one", 1}, {"two", 2}, {"three", 3}}));
                CHECK(j2.get<std::unordered_map<std::string, unsigned int>>() == (std::unordered_map<std::string, unsigned int> {{"one", 1u}, {"two", 2u}, {"three", 3u}}));
                CHECK(j3.get<std::unordered_map<std::string, double>>() == (std::unordered_map<std::string, double> {{"one", 1.1}, {"two", 2.2}, {"three", 3.3}}));
                CHECK(j4.get<std::unordered_map<std::string, bool>>() == (std::unordered_map<std::string, bool> {{"one", true}, {"two", false}, {"three", true}}));
                const auto m5 = j5.get<std::unordered_map<std::string, std::string>>();
                CHECK(m5 == (std::unordered_map<std::string, std::string> {{"one", "eins"}, {"two", "zwei"}, {"three", "drei"}}));
                CHECK(m5.at("one") == "eins");
            }

            SECTION("reserve is called on containers that support it (#5406)")
            {
                // build a larger object so that a missing/incorrect reserve()
                // call would be more likely to corrupt or drop elements
                json j_large;
                for (int i = 0; i < 100; ++i)
                {
                    j_large[std::to_string(i)] = i;
                }

                SECTION("std::unordered_map (supports reserve)")
                {
                    const auto m = j_large.get<std::unordered_map<std::string, int>>();
                    CHECK(m.size() == 100);
                    for (int i = 0; i < 100; ++i)
                    {
                        CHECK(m.at(std::to_string(i)) == i);
                    }
                }

                SECTION("std::map (no reserve, fallback path)")
                {
                    const auto m = j_large.get<std::map<std::string, int>>();
                    CHECK(m.size() == 100);
                    for (int i = 0; i < 100; ++i)
                    {
                        CHECK(m.at(std::to_string(i)) == i);
                    }
                }
            }

            SECTION("std::multimap")
            {
                CHECK(j1.get<std::multimap<std::string, int>>() == (std::multimap<std::string, int> {{"one", 1}, {"two", 2}, {"three", 3}}));
                CHECK(j2.get<std::multimap<std::string, unsigned int>>() == (std::multimap<std::string, unsigned int> {{"one", 1u}, {"two", 2u}, {"three", 3u}}));
                CHECK(j3.get<std::multimap<std::string, double>>() == (std::multimap<std::string, double> {{"one", 1.1}, {"two", 2.2}, {"three", 3.3}}));
                CHECK(j4.get<std::multimap<std::string, bool>>() == (std::multimap<std::string, bool> {{"one", true}, {"two", false}, {"three", true}}));
                const auto m5 = j5.get<std::multimap<std::string, std::string>>();
                CHECK(m5 == (std::multimap<std::string, std::string> {{"one", "eins"}, {"two", "zwei"}, {"three", "drei"}}));
                CHECK(m5.find("one")->second == "eins");
            }

            SECTION("std::unordered_multimap")
            {
                CHECK(j1.get<std::unordered_multimap<std::string, int>>() == (std::unordered_multimap<std::string, int> {{"one", 1}, {"two", 2}, {"three", 3}}));
                CHECK(j2.get<std::unordered_multimap<std::string, unsigned int>>() == (std::unordered_multimap<std::string, unsigned int> {{"one", 1u}, {"two", 2u}, {"three", 3u}}));
                CHECK(j3.get<std::unordered_multimap<std::string, double>>() == (std::unordered_multimap<std::string, double> {{"one", 1.1}, {"two", 2.2}, {"three", 3.3}}));
                CHECK(j4.get<std::unordered_multimap<std::string, bool>>() == (std::unordered_multimap<std::string, bool> {{"one", true}, {"two", false}, {"three", true}}));
                const auto m5 = j5.get<std::unordered_multimap<std::string, std::string>>();
                CHECK(m5 == (std::unordered_multimap<std::string, std::string> {{"one", "eins"}, {"two", "zwei"}, {"three", "drei"}}));
                CHECK(m5.find("one")->second == "eins");
            }

            SECTION("exception in case of a non-object type")
            {
                CHECK_THROWS_WITH_AS(
                    (json().get<std::map<std::string, int>>()),
                    "[json.exception.type_error.302] type must be object, but is null", json::type_error&);
            }
        }

        SECTION("array-like STL containers")
        {
            json const j1 = {1, 2, 3, 4};
            json const j2 = {1u, 2u, 3u, 4u};
            json const j3 = {1.2, 2.3, 3.4, 4.5};
            json const j4 = {true, false, true};
            json const j5 = {"one", "two", "three"};

            SECTION("std::list")
            {
                CHECK(j1.get<std::list<int>>() == (std::list<int> {1, 2, 3, 4}));
                CHECK(j2.get<std::list<unsigned int>>() == (std::list<unsigned int> {1u, 2u, 3u, 4u}));
                CHECK(j3.get<std::list<double>>() == (std::list<double> {1.2, 2.3, 3.4, 4.5}));
                CHECK(j4.get<std::list<bool>>() == (std::list<bool> {true, false, true}));
                CHECK(j5.get<std::list<std::string>>() == (std::list<std::string> {"one", "two", "three"}));
            }

            SECTION("std::forward_list")
            {
                CHECK(j1.get<std::forward_list<int>>() == (std::forward_list<int> {1, 2, 3, 4}));
                CHECK(j2.get<std::forward_list<unsigned int>>() == (std::forward_list<unsigned int> {1u, 2u, 3u, 4u}));
                CHECK(j3.get<std::forward_list<double>>() == (std::forward_list<double> {1.2, 2.3, 3.4, 4.5}));
                CHECK(j4.get<std::forward_list<bool>>() == (std::forward_list<bool> {true, false, true}));
                CHECK(j5.get<std::forward_list<std::string>>() == (std::forward_list<std::string> {"one", "two", "three"}));
            }

            SECTION("std::array")
            {
                CHECK(j1.get<std::array<int, 4>>() == (std::array<int, 4> {{1, 2, 3, 4}}));
                // only the first 3 elements of j2 are converted, since the target array is smaller
                CHECK(j2.get<std::array<unsigned int, 3>>() == (std::array<unsigned int, 3> {{1u, 2u, 3u}}));
                CHECK(j3.get<std::array<double, 4>>() == (std::array<double, 4> {{1.2, 2.3, 3.4, 4.5}}));
                CHECK(j4.get<std::array<bool, 3>>() == (std::array<bool, 3> {{true, false, true}}));
                CHECK(j5.get<std::array<std::string, 3>>() == (std::array<std::string, 3> {{"one", "two", "three"}}));

                SECTION("std::array is larger than JSON")
                {
                    std::array<int, 6> arr6 = {{1, 2, 3, 4, 5, 6}};
                    CHECK_THROWS_WITH_AS(j1.get_to(arr6), "[json.exception.out_of_range.401] "
                                         "array index 4 is out of range", json::out_of_range&);
                }

                SECTION("std::array is smaller than JSON")
                {
                    std::array<int, 2> arr2 = {{8, 9}};
                    j1.get_to(arr2);
                    CHECK(arr2[0] == 1);
                    CHECK(arr2[1] == 2);
                }
            }

            SECTION("std::valarray")
            {
                // valarray has no operator== that returns bool, so compare via a vector copy
                const auto v1 = j1.get<std::valarray<int>>();
                CHECK((std::vector<int>(std::begin(v1), std::end(v1)) == std::vector<int> {1, 2, 3, 4}));
                const auto v2 = j2.get<std::valarray<unsigned int>>();
                CHECK((std::vector<unsigned int>(std::begin(v2), std::end(v2)) == std::vector<unsigned int> {1u, 2u, 3u, 4u}));
                const auto v3 = j3.get<std::valarray<double>>();
                CHECK((std::vector<double>(std::begin(v3), std::end(v3)) == std::vector<double> {1.2, 2.3, 3.4, 4.5}));
                const auto v4 = j4.get<std::valarray<bool>>();
                CHECK((std::vector<bool>(std::begin(v4), std::end(v4)) == std::vector<bool> {true, false, true}));
                const auto v5 = j5.get<std::valarray<std::string>>();
                CHECK((std::vector<std::string>(std::begin(v5), std::end(v5)) == std::vector<std::string> {"one", "two", "three"}));
            }

            SECTION("std::vector")
            {
                CHECK(j1.get<std::vector<int>>() == (std::vector<int> {1, 2, 3, 4}));
                CHECK(j2.get<std::vector<unsigned int>>() == (std::vector<unsigned int> {1u, 2u, 3u, 4u}));
                CHECK(j3.get<std::vector<double>>() == (std::vector<double> {1.2, 2.3, 3.4, 4.5}));
                CHECK(j4.get<std::vector<bool>>() == (std::vector<bool> {true, false, true}));
                CHECK(j5.get<std::vector<std::string>>() == (std::vector<std::string> {"one", "two", "three"}));
            }

            SECTION("std::deque")
            {
                CHECK(j1.get<std::deque<int>>() == (std::deque<int> {1, 2, 3, 4}));
                CHECK(j2.get<std::deque<unsigned int>>() == (std::deque<unsigned int> {1u, 2u, 3u, 4u}));
                CHECK(j3.get<std::deque<double>>() == (std::deque<double> {1.2, 2.3, 3.4, 4.5}));
                CHECK(j4.get<std::deque<bool>>() == (std::deque<bool> {true, false, true}));
                CHECK(j5.get<std::deque<std::string>>() == (std::deque<std::string> {"one", "two", "three"}));
            }

            SECTION("std::set")
            {
                CHECK(j1.get<std::set<int>>() == (std::set<int> {1, 2, 3, 4}));
                CHECK(j2.get<std::set<unsigned int>>() == (std::set<unsigned int> {1u, 2u, 3u, 4u}));
                CHECK(j3.get<std::set<double>>() == (std::set<double> {1.2, 2.3, 3.4, 4.5}));
                CHECK(j4.get<std::set<bool>>() == (std::set<bool> {true, false, true}));
                CHECK(j5.get<std::set<std::string>>() == (std::set<std::string> {"one", "two", "three"}));
            }

            SECTION("std::unordered_set")
            {
                CHECK(j1.get<std::unordered_set<int>>() == (std::unordered_set<int> {1, 2, 3, 4}));
                CHECK(j2.get<std::unordered_set<unsigned int>>() == (std::unordered_set<unsigned int> {1u, 2u, 3u, 4u}));
                CHECK(j3.get<std::unordered_set<double>>() == (std::unordered_set<double> {1.2, 2.3, 3.4, 4.5}));
                CHECK(j4.get<std::unordered_set<bool>>() == (std::unordered_set<bool> {true, false, true}));
                CHECK(j5.get<std::unordered_set<std::string>>() == (std::unordered_set<std::string> {"one", "two", "three"}));
            }

            SECTION("std::map (array of pairs)")
            {
                const std::map<int, int> m{{0, 1}, {1, 2}, {2, 3}};
                json const j6 = m;

                auto m2 = j6.get<std::map<int, int>>();
                CHECK(m == m2);

                json const j7 = {0, 1, 2, 3};
                json const j8 = 2;
                CHECK_THROWS_WITH_AS((j7.get<std::map<int, int>>()),
                                     "[json.exception.type_error.302] type must be array, "
                                     "but is number", json::type_error&);
                CHECK_THROWS_WITH_AS((j8.get<std::map<int, int>>()),
                                     "[json.exception.type_error.302] type must be array, "
                                     "but is number", json::type_error&);

                SECTION("superfluous entries")
                {
                    json const j9 = {{0, 1, 2}, {1, 2, 3}, {2, 3, 4}};
                    m2 = j9.get<std::map<int, int>>();
                    CHECK(m == m2);
                }
            }

            SECTION("std::unordered_map (array of pairs)")
            {
                const std::unordered_map<int, int> m{{0, 1}, {1, 2}, {2, 3}};
                json const j6 = m;

                auto m2 = j6.get<std::unordered_map<int, int>>();
                CHECK(m == m2);

                json const j7 = {0, 1, 2, 3};
                json const j8 = 2;
                CHECK_THROWS_WITH_AS((j7.get<std::unordered_map<int, int>>()),
                                     "[json.exception.type_error.302] type must be array, "
                                     "but is number", json::type_error&);
                CHECK_THROWS_WITH_AS((j8.get<std::unordered_map<int, int>>()),
                                     "[json.exception.type_error.302] type must be array, "
                                     "but is number", json::type_error&);

                SECTION("superfluous entries")
                {
                    json const j9{{0, 1, 2}, {1, 2, 3}, {2, 3, 4}};
                    m2 = j9.get<std::unordered_map<int, int>>();
                    CHECK(m == m2);
                }
            }

            SECTION("exception in case of a non-object type")
            {
                // does type really must be an array? or it rather must not be null?
                // that's what I thought when other test like this one broke
                CHECK_THROWS_WITH_AS(
                    (json().get<std::list<int>>()),
                    "[json.exception.type_error.302] type must be array, but is null", json::type_error&);
                CHECK_THROWS_WITH_AS(
                    (json().get<std::vector<int>>()),
                    "[json.exception.type_error.302] type must be array, but is null", json::type_error&);
                CHECK_THROWS_WITH_AS(
                    (json().get<std::vector<json>>()),
                    "[json.exception.type_error.302] type must be array, but is null", json::type_error&);
                CHECK_THROWS_WITH_AS(
                    (json().get<std::list<json>>()),
                    "[json.exception.type_error.302] type must be array, but is null", json::type_error&);
                CHECK_THROWS_WITH_AS(
                    (json().get<std::valarray<int>>()),
                    "[json.exception.type_error.302] type must be array, but is null", json::type_error&);
                CHECK_THROWS_WITH_AS(
                    (json().get<std::map<int, int>>()),
                    "[json.exception.type_error.302] type must be array, but is null", json::type_error&);
            }
        }
    }
}

enum class cards {kreuz, pik, herz, karo};

// NOLINTNEXTLINE(misc-use-internal-linkage,misc-const-correctness) - false positive
NLOHMANN_JSON_SERIALIZE_ENUM(cards,
{
    {cards::kreuz, "kreuz"},
    {cards::pik, "pik"},
    {cards::pik, "puk"},  // second entry for cards::puk; will not be used
    {cards::herz, "herz"},
    {cards::karo, "karo"}
})

enum TaskState // NOLINT(cert-int09-c,readability-enum-initial-value,cppcoreguidelines-use-enum-class)
{
    TS_STOPPED,
    TS_RUNNING,
    TS_COMPLETED,
    TS_INVALID = -1,
};

// NOLINTNEXTLINE(misc-const-correctness,misc-use-internal-linkage) - false positive
NLOHMANN_JSON_SERIALIZE_ENUM(TaskState,
{
    {TS_INVALID, nullptr},
    {TS_STOPPED, "stopped"},
    {TS_RUNNING, "running"},
    {TS_COMPLETED, "completed"},
})

TEST_CASE("JSON to enum mapping")
{
    SECTION("enum class")
    {
        // enum -> json
        CHECK(json(cards::kreuz) == "kreuz");
        CHECK(json(cards::pik) == "pik");
        CHECK(json(cards::herz) == "herz");
        CHECK(json(cards::karo) == "karo");

        // json -> enum
        CHECK(cards::kreuz == json("kreuz"));
        CHECK(cards::pik == json("pik"));
        CHECK(cards::herz == json("herz"));
        CHECK(cards::karo == json("karo"));

        // invalid json -> first enum
        CHECK(cards::kreuz == json("what?").get<cards>());
    }

    SECTION("traditional enum")
    {
        // enum -> json
        CHECK(json(TS_STOPPED) == "stopped");
        CHECK(json(TS_RUNNING) == "running");
        CHECK(json(TS_COMPLETED) == "completed");
        CHECK(json(TS_INVALID) == json());

        // json -> enum
        CHECK(TS_STOPPED == json("stopped"));
        CHECK(TS_RUNNING == json("running"));
        CHECK(TS_COMPLETED == json("completed"));
        CHECK(TS_INVALID == json());

        // invalid json -> first enum
        CHECK(TS_INVALID == json("what?").get<TaskState>());
    }
}

enum class strict_cards {kreuz, pik, herz, karo, andere}; // andere not included in mapping

// NOLINTNEXTLINE(misc-use-internal-linkage,misc-const-correctness) - false positive
NLOHMANN_JSON_SERIALIZE_ENUM_STRICT(strict_cards,
{
    {strict_cards::kreuz, "kreuz"},
    {strict_cards::pik, "pik"},
    {strict_cards::pik, "puk"},  // second entry for cards::pik; will not be used
    {strict_cards::herz, "herz"},
    {strict_cards::karo, "karo"}
})

enum StrictTaskState // NOLINT(cert-int09-c,readability-enum-initial-value,cppcoreguidelines-use-enum-class)
{
    STRICT_TS_STOPPED,
    STRICT_TS_RUNNING,
    STRICT_TS_COMPLETED,
    STRICT_TS_OTHER, // STRICT_TS_OTHER not in mapping
    STRICT_TS_INVALID = -1,
};

// NOLINTNEXTLINE(misc-const-correctness,misc-use-internal-linkage) - false positive
NLOHMANN_JSON_SERIALIZE_ENUM_STRICT(StrictTaskState,
{
    {STRICT_TS_INVALID, nullptr},
    {STRICT_TS_STOPPED, "stopped"},
    {STRICT_TS_RUNNING, "running"},
    {STRICT_TS_COMPLETED, "completed"},
})

TEST_CASE("Strict JSON to enum mapping")
{
    SECTION("enum class")
    {
        // enum -> json
        CHECK(json(strict_cards::kreuz) == "kreuz");
        CHECK(json(strict_cards::pik) == "pik");
        CHECK(json(strict_cards::herz) == "herz");
        CHECK(json(strict_cards::karo) == "karo");

        // json -> enum
        CHECK(strict_cards::kreuz == json("kreuz"));
        CHECK(strict_cards::pik == json("pik"));
        CHECK(strict_cards::herz == json("herz"));
        CHECK(strict_cards::karo == json("karo"));

        // invalid json -> exception thrown
        json _;
        CHECK_THROWS_WITH_AS(_ = json("what?").get<strict_cards>(), "[json.exception.out_of_range.410] enum value out of range for strict_cards: \"what?\"", json::out_of_range&);

        // conversion of unmapped enum -> exception thrown
        CHECK_THROWS_WITH_AS(json(strict_cards::andere), "[json.exception.out_of_range.410] enum value out of range for strict_cards", json::out_of_range&);

        // invalid UTF-8 -> out_of_range.410, not the type_error.316 thrown while building the
        // message (regression test for #5667); such strings can reach get<Enum>() unvalidated,
        // e.g. from from_cbor()/from_msgpack() (#5529)
        const json j_invalid_utf8 = "\xFF";
        CHECK_THROWS_WITH_AS(_ = j_invalid_utf8.get<strict_cards>(), "[json.exception.out_of_range.410] enum value out of range for strict_cards: \"\xEF\xBF\xBD\"", json::out_of_range&);
    }

    SECTION("traditional enum")
    {
        // enum -> json
        CHECK(json(STRICT_TS_STOPPED) == "stopped");
        CHECK(json(STRICT_TS_RUNNING) == "running");
        CHECK(json(STRICT_TS_COMPLETED) == "completed");
        CHECK(json(STRICT_TS_INVALID) == json());

        // json -> enum
        CHECK(STRICT_TS_STOPPED == json("stopped"));
        CHECK(STRICT_TS_RUNNING == json("running"));
        CHECK(STRICT_TS_COMPLETED == json("completed"));
        CHECK(STRICT_TS_INVALID == json());

        // invalid json -> exception thrown
        json _;
        CHECK_THROWS_WITH_AS(_ = json("what?").get<StrictTaskState>(), "[json.exception.out_of_range.410] enum value out of range for StrictTaskState: \"what?\"", json::out_of_range&);

        // conversion of unmapped enum -> exception thrown
        CHECK_THROWS_WITH_AS(json(STRICT_TS_OTHER), "[json.exception.out_of_range.410] enum value out of range for StrictTaskState", json::out_of_range&);
    }
}


#ifdef JSON_HAS_CPP_17
#if JSON_HAS_FILESYSTEM || JSON_HAS_EXPERIMENTAL_FILESYSTEM
TEST_CASE("std::filesystem::path")
{
    SECTION("ascii")
    {
        json const j_string = "Path";
        auto p = j_string.template get<nlohmann::detail::std_fs::path>();
        json const j_path = p;

        CHECK(j_path.template get<std::string>() ==
              j_string.template get<std::string>());
    }

    SECTION("utf-8")
    {
        json const j_string = "P\xc4\x9b\xc5\xa1ina";
        auto p = j_string.template get<nlohmann::detail::std_fs::path>();
        json const j_path = p;

        CHECK(j_path.template get<std::string>() ==
              j_string.template get<std::string>());
    }
}
#endif

// the ADL to_json overload for std::u8string only exists under the same guard
// as std::filesystem::path support (it is otherwise only reached indirectly,
// via std::filesystem::path::u8string()) -- mirror both #if conditions from
// include/nlohmann/detail/conversions/to_json.hpp exactly
#if JSON_HAS_FILESYSTEM || JSON_HAS_EXPERIMENTAL_FILESYSTEM
#if defined(__cpp_lib_char8_t)
TEST_CASE("std::u8string")
{
    SECTION("ascii")
    {
        const std::u8string s = u8"Path";
        json const j = s;

        CHECK(j.template get<std::string>() == "Path");
    }

    SECTION("utf-8")
    {
        // use \u universal-character-names (rather than raw \x byte escapes
        // or literal non-ASCII source bytes) to compose the multi-byte UTF-8
        // encoding -- MSVC treats \x escapes used that way inside a u8
        // literal as a nonstandard extension (warning C5321), which some of
        // our CI configs promote to an error; \u is portable and produces
        // the exact same encoded bytes without depending on the source
        // file's encoding
        const std::u8string s = u8"P\u011B\u0161ina";
        json const j = s;

        CHECK(j.template get<std::string>() == "P\xc4\x9b\xc5\xa1ina");
    }
}
#endif
#endif

#if !defined(JSON_NOEXCEPTION)
namespace
{
// a type whose to_json reports an error by throwing, used below to check that
// converting a std::optional<T> to JSON propagates an exception thrown while
// converting its contained value instead of calling std::terminate (#5642)
struct throwing_to_json_type {};

[[noreturn]] void to_json(json& /*unused*/, const throwing_to_json_type& /*unused*/)
{
    throw std::runtime_error("cannot serialize throwing_to_json_type");
}
}  // namespace
#endif

TEST_CASE("std::optional")
{
    SECTION("null")
    {
        const json j_null;
        const std::optional<std::string> opt_null;

        CHECK(json(opt_null) == j_null);
        CHECK(j_null.get<std::optional<std::string>>() == std::nullopt);

        // Constructing std::optional<T> directly from JSON null throws because
        // std::optional's own converting constructor is chosen over basic_json's
        // operator T(). This is a language-level limitation (std::optional<T> is
        // constructible from T, and T is constructible from basic_json via the
        // operator); there is no SFINAE path that distinguishes "call from inside
        // std::optional's constructor" from "direct call". Use get<std::optional<T>>()
        // or get_to() instead for correct null handling. See #4864 and #5246.
        CHECK_THROWS_WITH_AS(std::optional<std::string>(j_null),
                             "[json.exception.type_error.302] type must be string, but is null", json::type_error&);
        CHECK_THROWS_WITH_AS(std::optional<int>(j_null),
                             "[json.exception.type_error.302] type must be number, but is null", json::type_error&);

        // Assignment goes through the same overload resolution as direct
        // construction, so it throws for the same reason. This relies on
        // basic_json's implicit conversion operator, so it only applies
        // when JSON_USE_IMPLICIT_CONVERSIONS is enabled (the default).
#if JSON_USE_IMPLICIT_CONVERSIONS
        std::optional<std::string> opt_assign;
        CHECK_THROWS_WITH_AS(opt_assign = j_null,
                             "[json.exception.type_error.302] type must be string, but is null", json::type_error&);
#endif

        // get_to() is the correct way to obtain std::nullopt from a JSON null.
        std::optional<std::string> opt_get_to = "placeholder";
        j_null.get_to(opt_get_to);
        CHECK(opt_get_to == std::nullopt);
    }

    SECTION("string")
    {
        json j_string = "string";
        std::optional<std::string> opt_string = "string";

        CHECK(json(opt_string) == j_string);
        CHECK(std::optional<std::string>(j_string) == opt_string);
    }

    SECTION("bool")
    {
        json j_bool = true;
        std::optional<bool> opt_bool = true;

        CHECK(json(opt_bool) == j_bool);
        CHECK(std::optional<bool>(j_bool) == opt_bool);
    }

    SECTION("number")
    {
        json j_number = 1;
        std::optional<int> opt_int = 1;

        CHECK(json(opt_int) == j_number);
        CHECK(j_number.get<std::optional<int>>() == opt_int);
    }

    SECTION("array")
    {
        json j_array = {1, 2, nullptr};
        std::vector<std::optional<int>> opt_array = {{1, 2, std::nullopt}};

        CHECK(json(opt_array) == j_array);
        CHECK(j_array.get<std::vector<std::optional<int>>>() == opt_array);
    }

    SECTION("object")
    {
        json j_object = {{"one", 1}, {"two", 2}, {"zero", nullptr}};
        std::map<std::string, std::optional<int>> opt_object {{"one", 1}, {"two", 2}, {"zero", std::nullopt}};

        CHECK(json(opt_object) == j_object);
        CHECK(std::map<std::string, std::optional<int>>(j_object) == opt_object);
    }

#if !defined(JSON_NOEXCEPTION)
    SECTION("exception from contained value's to_json propagates (#5642)")
    {
        // to_json(BasicJsonType&, const std::optional<T>&) must not be
        // noexcept: it calls T's to_json, which may throw (a user-defined
        // to_json that reports an error, or std::bad_alloc for T =
        // std::string/vector/json). Before the fix, this called
        // std::terminate() instead of letting the exception propagate.
        const std::optional<throwing_to_json_type> opt = throwing_to_json_type{};
        CHECK_THROWS_WITH_AS(json(opt), "cannot serialize throwing_to_json_type", std::runtime_error&);

        // the conversion is noexcept exactly when converting the contained value is
        static_assert(!std::is_nothrow_constructible<json, const std::optional<throwing_to_json_type>&>::value, "");
        static_assert(std::is_nothrow_constructible<json, const std::optional<int>&>::value, "");
    }
#endif
}
#endif

#ifdef JSON_HAS_CPP_17
    #undef JSON_HAS_CPP_17
#endif

#ifdef JSON_HAS_CPP_14
    #undef JSON_HAS_CPP_14
#endif
DOCTEST_CLANG_SUPPRESS_WARNING_POP