#include <gtest/gtest.h>
#include <m5_utility/stl/expected.hpp>

#define TOKENPASTE(x, y)  x##y
#define TOKENPASTE2(x, y) TOKENPASTE(x, y)
#undef STATIC_REQUIRE
#define STATIC_REQUIRE(e)                            \
    constexpr bool TOKENPASTE2(rqure, __LINE__) = e; \
    (void)TOKENPASTE2(rqure, __LINE__);              \
    EXPECT_TRUE(e);

TEST(Expected, MapExtensions)
{
    auto mul2     = [](int a) { return a * 2; };
    auto ret_void = [](int a) { (void)a; };

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = e.map(mul2);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 42);
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = e.map(mul2);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 42);
    }

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = std::move(e).map(mul2);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 42);
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = std::move(e).map(mul2);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 42);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.map(mul2);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 21);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.map(mul2);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 21);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).map(mul2);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 21);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).map(mul2);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 21);
    }

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = e.map(ret_void);
        EXPECT_TRUE(ret);
        STATIC_REQUIRE((std::is_same<decltype(ret), m5::stl::expected<void, int>>::value));
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = e.map(ret_void);
        EXPECT_TRUE(ret);
        STATIC_REQUIRE((std::is_same<decltype(ret), m5::stl::expected<void, int>>::value));
    }

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = std::move(e).map(ret_void);
        EXPECT_TRUE(ret);
        STATIC_REQUIRE((std::is_same<decltype(ret), m5::stl::expected<void, int>>::value));
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = std::move(e).map(ret_void);
        EXPECT_TRUE(ret);
        STATIC_REQUIRE((std::is_same<decltype(ret), m5::stl::expected<void, int>>::value));
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.map(ret_void);
        EXPECT_TRUE(!ret);
        STATIC_REQUIRE((std::is_same<decltype(ret), m5::stl::expected<void, int>>::value));
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.map(ret_void);
        EXPECT_TRUE(!ret);
        STATIC_REQUIRE((std::is_same<decltype(ret), m5::stl::expected<void, int>>::value));
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).map(ret_void);
        EXPECT_TRUE(!ret);
        STATIC_REQUIRE((std::is_same<decltype(ret), m5::stl::expected<void, int>>::value));
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).map(ret_void);
        EXPECT_TRUE(!ret);
        STATIC_REQUIRE((std::is_same<decltype(ret), m5::stl::expected<void, int>>::value));
    }

    // mapping functions which return references
    {
        m5::stl::expected<int, int> e(42);
        auto ret = e.map([](int& i) -> int& { return i; });
        EXPECT_TRUE(ret);
        EXPECT_TRUE(ret == 42);
    }
}

TEST(Expected, MapErrorExtensions)
{
    auto mul2     = [](int a) { return a * 2; };
    auto ret_void = [](int a) { (void)a; };

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = e.map_error(mul2);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 21);
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = e.map_error(mul2);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 21);
    }

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = std::move(e).map_error(mul2);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 21);
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = std::move(e).map_error(mul2);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 21);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.map_error(mul2);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 42);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.map_error(mul2);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 42);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).map_error(mul2);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 42);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).map_error(mul2);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 42);
    }

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = e.map_error(ret_void);
        EXPECT_TRUE(ret);
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = e.map_error(ret_void);
        EXPECT_TRUE(ret);
    }

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = std::move(e).map_error(ret_void);
        EXPECT_TRUE(ret);
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = std::move(e).map_error(ret_void);
        EXPECT_TRUE(ret);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.map_error(ret_void);
        EXPECT_TRUE(!ret);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.map_error(ret_void);
        EXPECT_TRUE(!ret);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).map_error(ret_void);
        EXPECT_TRUE(!ret);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).map_error(ret_void);
        EXPECT_TRUE(!ret);
    }
}

TEST(Expected, AndThenExtensions)
{
    auto succeed = [](int a) {
        (void)a;
        return m5::stl::expected<int, int>(21 * 2);
    };
    auto fail = [](int a) {
        (void)a;
        return m5::stl::expected<int, int>(m5::stl::unexpect, 17);
    };

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = e.and_then(succeed);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 42);
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = e.and_then(succeed);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 42);
    }

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = std::move(e).and_then(succeed);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 42);
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = std::move(e).and_then(succeed);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 42);
    }

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = e.and_then(fail);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 17);
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = e.and_then(fail);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 17);
    }

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = std::move(e).and_then(fail);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 17);
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = std::move(e).and_then(fail);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 17);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.and_then(succeed);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 21);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.and_then(succeed);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 21);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).and_then(succeed);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 21);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).and_then(succeed);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 21);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.and_then(fail);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 21);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.and_then(fail);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 21);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).and_then(fail);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 21);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).and_then(fail);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 21);
    }
}

TEST(Expected, or_else)
{
    using eptr   = std::unique_ptr<int>;
    auto succeed = [](int a) {
        (void)a;
        return m5::stl::expected<int, int>(21 * 2);
    };
    auto succeedptr = [](eptr e) {
        (void)e;
        return m5::stl::expected<int, eptr>(21 * 2);
    };
    auto fail = [](int a) {
        (void)a;
        return m5::stl::expected<int, int>(m5::stl::unexpect, 17);
    };
    auto failptr = [](eptr e) {
        *e = 17;
        return m5::stl::expected<int, eptr>(m5::stl::unexpect, std::move(e));
    };
    auto failvoid    = [](int) {};
    auto failvoidptr = [](const eptr&) { /* don't consume */ };
    auto consumeptr  = [](eptr) {};
    auto make_u_int  = [](int n) { return std::unique_ptr<int>(new int(n)); };

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = e.or_else(succeed);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 21);
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = e.or_else(succeed);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 21);
    }

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = std::move(e).or_else(succeed);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 21);
    }

    {
        m5::stl::expected<int, eptr> e = 21;
        auto ret                       = std::move(e).or_else(succeedptr);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 21);
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = std::move(e).or_else(succeed);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 21);
    }

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = e.or_else(fail);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 21);
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = e.or_else(fail);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 21);
    }

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = std::move(e).or_else(fail);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(ret == 21);
    }

    {
        m5::stl::expected<int, eptr> e = 21;
        auto ret                       = std::move(e).or_else(failptr);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(ret == 21);
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = std::move(e).or_else(fail);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 21);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.or_else(succeed);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 42);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.or_else(succeed);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 42);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).or_else(succeed);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 42);
    }

    {
        m5::stl::expected<int, eptr> e(m5::stl::unexpect, make_u_int(21));
        auto ret = std::move(e).or_else(succeedptr);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 42);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).or_else(succeed);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 42);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.or_else(fail);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 17);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.or_else(failvoid);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 21);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.or_else(fail);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 17);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.or_else(failvoid);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 21);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).or_else(fail);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 17);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).or_else(failvoid);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 21);
    }

    {
        m5::stl::expected<int, eptr> e(m5::stl::unexpect, make_u_int(21));
        auto ret = std::move(e).or_else(failvoidptr);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(*ret.error() == 21);
    }

    {
        m5::stl::expected<int, eptr> e(m5::stl::unexpect, make_u_int(21));
        auto ret = std::move(e).or_else(consumeptr);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == nullptr);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).or_else(fail);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 17);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).or_else(failvoid);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 21);
    }
}

TEST(Expected, TransformExtensions)
{
    auto mul2     = [](int a) { return a * 2; };
    auto ret_void = [](int a) { (void)a; };

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = e.transform(mul2);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 42);
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = e.transform(mul2);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 42);
    }

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = std::move(e).transform(mul2);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 42);
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = std::move(e).transform(mul2);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 42);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.transform(mul2);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 21);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.transform(mul2);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 21);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).transform(mul2);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 21);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).transform(mul2);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 21);
    }

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = e.transform(ret_void);
        EXPECT_TRUE(ret);
        STATIC_REQUIRE((std::is_same<decltype(ret), m5::stl::expected<void, int>>::value));
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = e.transform(ret_void);
        EXPECT_TRUE(ret);
        STATIC_REQUIRE((std::is_same<decltype(ret), m5::stl::expected<void, int>>::value));
    }

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = std::move(e).transform(ret_void);
        EXPECT_TRUE(ret);
        STATIC_REQUIRE((std::is_same<decltype(ret), m5::stl::expected<void, int>>::value));
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = std::move(e).transform(ret_void);
        EXPECT_TRUE(ret);
        STATIC_REQUIRE((std::is_same<decltype(ret), m5::stl::expected<void, int>>::value));
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.transform(ret_void);
        EXPECT_TRUE(!ret);
        STATIC_REQUIRE((std::is_same<decltype(ret), m5::stl::expected<void, int>>::value));
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.transform(ret_void);
        EXPECT_TRUE(!ret);
        STATIC_REQUIRE((std::is_same<decltype(ret), m5::stl::expected<void, int>>::value));
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).transform(ret_void);
        EXPECT_TRUE(!ret);
        STATIC_REQUIRE((std::is_same<decltype(ret), m5::stl::expected<void, int>>::value));
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).transform(ret_void);
        EXPECT_TRUE(!ret);
        STATIC_REQUIRE((std::is_same<decltype(ret), m5::stl::expected<void, int>>::value));
    }

    // mapping functions which return references
    {
        m5::stl::expected<int, int> e(42);
        auto ret = e.transform([](int& i) -> int& { return i; });
        EXPECT_TRUE(ret);
        EXPECT_TRUE(ret == 42);
    }
}

TEST(Expected, TransformErrorExtensions)
{
    auto mul2     = [](int a) { return a * 2; };
    auto ret_void = [](int a) { (void)a; };

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = e.transform_error(mul2);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 21);
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = e.transform_error(mul2);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 21);
    }

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = std::move(e).transform_error(mul2);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 21);
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = std::move(e).transform_error(mul2);
        EXPECT_TRUE(ret);
        EXPECT_TRUE(*ret == 21);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.transform_error(mul2);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 42);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.transform_error(mul2);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 42);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).transform_error(mul2);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 42);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).transform_error(mul2);
        EXPECT_TRUE(!ret);
        EXPECT_TRUE(ret.error() == 42);
    }

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = e.transform_error(ret_void);
        EXPECT_TRUE(ret);
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = e.transform_error(ret_void);
        EXPECT_TRUE(ret);
    }

    {
        m5::stl::expected<int, int> e = 21;
        auto ret                      = std::move(e).transform_error(ret_void);
        EXPECT_TRUE(ret);
    }

    {
        const m5::stl::expected<int, int> e = 21;
        auto ret                            = std::move(e).transform_error(ret_void);
        EXPECT_TRUE(ret);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.transform_error(ret_void);
        EXPECT_TRUE(!ret);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = e.transform_error(ret_void);
        EXPECT_TRUE(!ret);
    }

    {
        m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).transform_error(ret_void);
        EXPECT_TRUE(!ret);
    }

    {
        const m5::stl::expected<int, int> e(m5::stl::unexpect, 21);
        auto ret = std::move(e).transform_error(ret_void);
        EXPECT_TRUE(!ret);
    }
}

struct S {
    int x;
};

struct F {
    int x;
};

TEST(Expected, issue14)
{
    auto res = m5::stl::expected<S, F>{m5::stl::unexpect, F{}};

    res.map_error([](F f) { (void)f; });
}

TEST(Expected, issue32)
{
    int i = 0;
    m5::stl::expected<void, int> a;
    a.map([&i] { i = 42; });
    EXPECT_TRUE(i == 42);

    auto x = a.map([] { return 42; });
    EXPECT_TRUE(*x == 42);
}