class Rack::Test::CookieJar

def merge(raw_cookies, uri = nil)

Cookies should be separated with a newline.
if the cookie is valid for the given URI.
Add a string of raw cookie information to the cookie jar, 
def merge(raw_cookies, uri = nil)
  return unless raw_cookies
  raw_cookies = raw_cookies.split("\n") if raw_cookies.is_a? String
  raw_cookies.each do |raw_cookie|
    next if raw_cookie.empty?
    cookie = Cookie.new(raw_cookie, uri, @default_host)
    self << cookie if cookie.valid?(uri)
  end
end