Mock return value std::shared_ptr

Hi,

  is it similar case for sharet_ptr? I have a method
 

std::shared_ptr<char[]> MBRegister::ReadData(const int regAddr, const int regCount)
{
    std::lock_guard<std::mutex> lg(lock);
    char* res = nullptr;
    if (regAddr >= 0 && regAddr + (regCount-1) <= registerCount) 
    {
        res = new char[regCount * 2];        

        char* startRead = buffer + (regAddr * 2);
        errno_t error = memcpy_s(res, regCount * 2, startRead, regCount * 2);
        if (error != 0) 
        {
            delete[] res;
            res = nullptr;
        }        
    }

    return std::shared_ptr<char[]>(res);
}

I'm not sure how mock this method by using PRIVATE_WHEN_CALLED, or other construct.

Thank you

Daril