# File lib/specinfra.rb, line 14
    def backend
      type = Specinfra.configuration.backend
      if type.nil?
        if Specinfra.configuration.error_on_missing_backend_type
          raise "No backend type is specified."
        end

        warn "No backend type is specified. Fall back to :exec type."
        type = :exec
      end
      eval "Specinfra::Backend::#{type.to_s.to_camel_case}.instance"
    end