OmniAuth::ReturnPathMiddleware

return_path_middleware.rb

module OmniAuth
  class ReturnPathMiddleware

    def initialize(app)
      @app = app
    end

    def call(env)
      if auth_request?(env) && asseptable_referer?(env)
        save_referer(env)
      end
      @app.call(env)
    end

    private

    def auth_regexp
      %r{^(?:/auth/\w+|/user/sign_\w\w)/?$}
    end

    def asseptable_referer?(env)
      env['HTTP_REFERER'] !~ auth_regexp
    end

    def auth_request?(env)
      env['REQUEST_PATH'] =~ auth_regexp
    end

    def save_referer(env)
      referer = env['HTTP_REFERER']
      Rails.logger.debug("return path to be saved in session: #{referer}")
      env['rack.session']['auth.return_path'] = referer
    end

  end
end

return_path_middleware_spec.rb

# coding: UTF-8

require 'spec_helper'

shared_examples_for "path saver" do

  it "saves HTTP_REFERER into session['auth.return_path']" do
    user_visits('/page', @req_path)
    saved_path.should == '/page'
  end

  it "saves nil if no HTTP_REFERER in env" do
    user_visits(@req_path)
    saved_path.should be_nil
  end

  it "does not overwrite entire session" do
    session['existent_key'] = 1
    user_visits('/page', @req_path)
    session['existent_key'].should == 1
  end

end

describe OmniAuth::ReturnPathMiddleware do

  before :each do
    @app = Proc.new {}
    @env = { 'rack.session' => {} }
  end

  subject do
    OmniAuth::ReturnPathMiddleware.new(@app)
  end

  def session
    @env['rack.session']
  end

  def saved_path
    session['auth.return_path']
  end

  def user_visits(*pages)
    @prev_page = nil
    pages.each do |page|
      @env['HTTP_REFERER'] = @prev_page
      @env['REQUEST_PATH'] = page
      subject.call(@env)
      @prev_page = page
    end
  end

  context "REQUEST_PATH is /user/sign_in" do

    before :each do
      @req_path = '/user/sign_in'
    end

    it_behaves_like "path saver"

  end

  context "REQUEST_PATH is omiauth entry path /auth/:provider" do

    before :each do
      @req_path = '/auth/twitter'
    end

    it_behaves_like "path saver"

    context "where are a few /user/sign* pages" do

      it "preserves previously saved path" do

        user_visits(*%w{
          /page
          /user/sign_in/
          /user/sign_up
          /auth/twitter/
        })
        saved_path.should == '/page'

        user_visits(*%w{
          /page1
          /user/sign_in
          /user/sign_up
          /page2
          /auth/twitter
        })

        saved_path.should == '/page2'

      end

    end

  end

  context "users returns from provider to callback or failure" do

    it "does not affect saved path" do
      pages = %w{
        /page
        /user/sign_in
        /user/sign_up
        /auth/twitter
      }

      # Редирект с социальной сети происходит без HTTP_REFERER
      # поэтому используем nil, чтобы симулировать это
      user_visits(*pages, nil, '/auth/twitter/callback')

      saved_path.should == '/page'

      user_visits(*pages, nil, '/auth/twitter/failure')

      saved_path.should == '/page'

    end

  end

  context "REQUEST_PATH is not omniauth path" do

    it "does not touch session" do
      user_visits('/page', '/noneauth/twitter')
      saved_path.should be_nil
    end

  end
end