Method receive

tests/test_asio_transport.cpp:109–114

            asio::write(s, asio::buffer(d.data(), d.size()));
        }
        std::size_t receive(std::span<std::byte> dst) override {
            asio::error_code ec;
            const std::size_t n =
                s.read_some(asio::buffer(dst.data(), dst.size()), ec);
            return ec ? 0 : n;
        }
        bool has_data() const override {
            asio::error_code ec;
            return s.available(ec) > 0 && !ec;