Function join

tests/framework/Utils.h:105–110

 */
template <typename T, typename std::enable_if<std::is_same<typename T::value_type, std::string>::value, int>::type = 0>
std::string join(T first, T last, const std::string &separator)
{
    return std::accumulate(std::next(first), last, *first,
                           [&separator](const std::string &base, const std::string &suffix)
                           { return base + separator + suffix; });
}

/** Helper function to concatenate multiple values.
 *