module ActionDispatch::Assertions::ResponseAssertions

def assert_redirected_to(options = {}, message=nil)

assert_redirected_to %r(\Ahttp://example.org)
# asserts that the redirection matches the regular expression

assert_redirected_to @customer
# assert that the redirection was to the url for @customer

assert_redirected_to login_url
# assert that the redirection was to the named route login_url

assert_redirected_to controller: "weblog", action: "index"
# assert that the redirection was to the "index" action on the WeblogController

match the redirection of redirect_to(controller: "weblog", action: "show") and so on.
This match can be partial, such that assert_redirected_to(controller: "weblog") will also
Assert that the redirection options passed in match those of the redirect called in the latest action. 
def assert_redirected_to(options = {}, message=nil)
  assert_response(:redirect, message)
  return true if options === @response.location
  redirect_is       = normalize_argument_to_redirection(@response.location)
  redirect_expected = normalize_argument_to_redirection(options)
  message ||= "Expected response to be a redirect to <#{redirect_expected}> but was a redirect to <#{redirect_is}>"
  assert_operator redirect_expected, :===, redirect_is, message
end

def assert_response(type, message = nil)

assert_response 401
# assert that the response code was status code 401 (unauthorized)

assert_response :redirect
# assert that the response was a redirection

See Rack::Utils::SYMBOL_TO_STATUS_CODE for a full list.
or its symbolic equivalent assert_response(:not_implemented).
You can also pass an explicit status number like assert_response(501)

* :error - Status code was in the 500-599 range
* :missing - Status code was 404
* :redirect - Status code was in the 300-399 range
* :success - Status code was in the 200-299 range

Asserts that the response is one of the following types: 
def assert_response(type, message = nil)
  message ||= "Expected response to be a <#{type}>, but was <#{@response.response_code}>"
  if Symbol === type
    if [:success, :missing, :redirect, :error].include?(type)
      assert @response.send("#{type}?"), message
    else
      code = Rack::Utils::SYMBOL_TO_STATUS_CODE[type]
      assert_equal code, @response.response_code, message
    end
  else
    assert_equal type, @response.response_code, message
  end
end

def normalize_argument_to_redirection(fragment) 

def normalize_argument_to_redirection(fragment)
  normalized = case fragment
    when Regexp
      fragment
    when %r{^\w[A-Za-z\d+.-]*:.*}
      fragment
    when String
      @request.protocol + @request.host_with_port + fragment
    when :back
      raise RedirectBackError unless refer = @request.headers["Referer"]
      refer
    else
      @controller.url_for(fragment)
    end
  normalized.respond_to?(:delete) ? normalized.delete("\0\r\n") : normalized
end

def parameterize(value)

Proxy to to_param if the object will respond to it. 
def parameterize(value)
  value.respond_to?(:to_param) ? value.to_param : value
end