testing.h

/*******************************************************************************
 * Copyright (C) 2026 Commissariat a l'energie atomique et aux energies alternatives (CEA)
 * Copyright (C) 2026 Julien Bigot <julien@julien-bigot.fr>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * * Neither the name of CEA nor the names of its contributors may be used to
 *   endorse or promote products derived from this software without specific
 *   prior written permission.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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 ******************************************************************************/
 
#ifndef PDI_TESTING_H_
#define PDI_TESTING_H_
 
// this is a header-only file because we don't want to depend on a given version of gtest/gmock
 
#include <algorithm>
#include <concepts>
#include <filesystem>
#include <limits>
#include <random>
#include <ranges>
#include <type_traits>
 
#include <gmock/gmock.h>
#include <gtest/gtest.h>
 
#include <paraconf.h>
#include <pdi.h>
 
namespace PDI {

template < class T, class G >
concept initializable_from = requires(T t, G& gen) {
    {
        t.init_from(gen)
    };
};

template <class T, class G>
concept buildable_from = std::constructible_from<T, G&> && requires(G& g) {
    {
        T(g)
    };
    {
        ::new T(g)
    };
};

template <class T>
concept distribution_safe_integral
    = std::same_as<T, short> || std::same_as<T, unsigned short> || std::same_as<T, int> || std::same_as<T, unsigned int> || std::same_as<T, long>
   || std::same_as<T, unsigned long> || std::same_as<T, long long> || std::same_as<T, unsigned long long>;

static inline void random_init(std::uniform_random_bit_generator auto& gen, distribution_safe_integral auto& t)
{
    using T = std::remove_reference_t<decltype(t)>;
    t = std::uniform_int_distribution<T>(std::numeric_limits<T>::min())(gen);
}

static inline void random_init(std::uniform_random_bit_generator auto& gen, std::floating_point auto& t)
{
    t = std::normal_distribution<std::remove_reference_t<decltype(t)>>{}(gen);
}

static inline void random_init(std::uniform_random_bit_generator auto& gen, std::ranges::input_range auto& t)
{
    std::for_each(std::begin(t), std::end(t), [&](std::ranges::range_value_t<decltype(t)>& v) { random_init(gen, v); });
}

static inline void random_init(std::uniform_random_bit_generator auto& gen, initializable_from<decltype(gen)> auto& t)
{
    t.init_from(gen);
}

template <typename T, std::uniform_random_bit_generator G>
requires(!std::ranges::input_range<T> && !initializable_from<T, G> && buildable_from<T, G> && std::assignable_from<T&, T &&>)
static inline void random_init(G& gen, T& t)
{
    t = T(gen);
}

template <typename T, std::uniform_random_bit_generator G>
requires buildable_from<T, G>
static inline T make_random(G& gen)
{
    return T(gen);
}

template <typename T, std::uniform_random_bit_generator G>
requires(!buildable_from<T, G>, std::default_initializable<T>)
static inline T make_random(G& gen)
{
    T result;
    random_init(gen, result);
    return result;
}

// this is a header-only class because we don't want to depend on a given version of gtest/gmock
class PdiTest: public ::testing::Test
{
    std::filesystem::path m_workdir;

    std::filesystem::path m_tmpdir;

    PC_tree_t m_conf = {PC_NODE_NOT_FOUND, nullptr, nullptr};

    std::mt19937_64 m_random_generator;

    static void s_pdi_errhandler(PDI_status_t status, const char* message, void* context)
    {
        static_cast<PdiTest*>(context)->PdiError(status, message);
    }
 
protected:
    inline PdiTest();
 
    inline ~PdiTest();

    template <typename T>
    inline T make_a()
    {
        return ::PDI::make_random<T>(m_random_generator);
    }

    inline void with_file(std::filesystem::path file) { std::filesystem::create_symlink((m_workdir / file), (m_tmpdir / file.filename())); }

    inline void InitPdi(PC_tree_t tree);

    inline void FinalizePdi();
 
    MOCK_METHOD(void, PdiError, (PDI_status_t, char const *), (const));
};
 
PdiTest::PdiTest()
    : m_workdir(std::filesystem::canonical(std::filesystem::current_path()))
{
    static thread_local auto random_generator([]() {
        if (int gseed = ::testing::UnitTest::GetInstance()->random_seed()) {
            return std::mt19937_64(gseed);
        } else {
            std::random_device source;
            std::array<unsigned, std::mt19937_64::state_size> random_seed_data;
            std::generate(std::begin(random_seed_data), std::end(random_seed_data), std::ref(source));
            std::seed_seq seed(std::begin(random_seed_data), std::end(random_seed_data));
            return std::mt19937_64(seed);
        }
    }());
    auto const filename = [&]() {
        static constexpr char const VALID_FILE_CHARS[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-";
        // -1 for closed set and -1 for ending \0 => -2
        std::uniform_int_distribution<size_t> random(0, std::ranges::size(VALID_FILE_CHARS) - 2);
        std::string filename(16, '\0');
        std::generate(filename.begin(), filename.end(), [&]() { return VALID_FILE_CHARS[random(random_generator)]; });
        auto&& test_info = *::testing::UnitTest::GetInstance()->current_test_info();
        return std::string("pdi_tst_dir.") + test_info.test_suite_name() + "." + test_info.name() + "." + filename;
    }();
    m_tmpdir = m_workdir / filename;
    std::filesystem::create_directory(m_tmpdir);
    std::filesystem::current_path(m_tmpdir);
    EXPECT_CALL(*this, PdiError(testing::_, testing::_)).Times(0);
}
 
inline void PdiTest::InitPdi(PC_tree_t tree)
{
    FinalizePdi();
    ASSERT_EQ(PC_OK, PC_status(tree));
    PDI_errhandler({s_pdi_errhandler, this});
    if (!PDI_init(tree)) {
        m_conf = tree;
    }
}
 
inline void PdiTest::FinalizePdi()
{
    if (!PC_status(m_conf)) {
        ASSERT_EQ(PDI_OK, PDI_finalize());
        EXPECT_EQ(PC_OK, PC_tree_destroy(&m_conf));
        m_conf = {PC_NODE_NOT_FOUND, nullptr, nullptr};
    }
}
 
inline PdiTest::~PdiTest()
{
    FinalizePdi();
    std::filesystem::current_path(m_workdir);
    std::filesystem::remove_all(m_tmpdir);
}
 
} // namespace PDI
 
#endif