Method MapGenerator

tests/catch.hpp:3782–3786

    public:
        template <typename F2 = Func>
        MapGenerator(F2&& function, GeneratorWrapper<U>&& generator) :
            m_generator(std::move(generator)),
            m_function(std::forward<F2>(function)),
            m_cache(m_function(m_generator.get()))
        {}

        T const& get() const override {
            return m_cache;