new (Rack::MockResponse)

    # File lib/rack/mock.rb, line 113
        def initialize(status, headers, body, errors=StringIO.new(""))
          @status = status.to_i

          @original_headers = headers
          @headers = Rack::Utils::HeaderHash.new
          headers.each { |field, values|
            values.each { |value|
              @headers[field] = value
            }
            @headers[field] = ""  if values.empty?
          }

          @body = ""
          body.each { |part| @body << part }

          @errors = errors.string
        end