Method on_message

cpp/src/context_test.cpp:84–93

    }

    void on_message(proton::delivery &d, proton::message &msg) override {
        std::string data = "delivery-user-data";
        // Set user context 'data' on delivery.
        d.user_data(&data);
        ASSERT_EQUAL(&data, d.user_data());

        d.receiver().close();
        d.connection().close();
        listener.stop();
    }
};

class test_client : public proton::messaging_handler {