An IntegrationTest is one that spans multiple controllers and actions, tying them all together to ensure they work together as expected. It tests more completely than either unit or functional tests do, exercising the entire stack, from the dispatcher to the database.

At its simplest, you simply extend IntegrationTest and write your tests using the get/post methods:

  require "#{File.dirname(__FILE__)}/test_helper"

  class ExampleTest < ActionController::IntegrationTest
    fixtures :people

    def test_login
      # get the login page
      get "/login"
      assert_equal 200, status

      # post the login and follow through to the home page
      post "/login", :username => people(:jamis).username,
        :password => people(:jamis).password
      follow_redirect!
      assert_equal 200, status
      assert_equal "/home", path
    end
  end

However, you can also have multiple session instances open per test, and even extend those instances with assertions and methods to create a very powerful testing DSL that is specific for your application. You can even reference any named routes you happen to have defined!

  require "#{File.dirname(__FILE__)}/test_helper"

  class AdvancedTest < ActionController::IntegrationTest
    fixtures :people, :rooms

    def test_login_and_speak
      jamis, david = login(:jamis), login(:david)
      room = rooms(:office)

      jamis.enter(room)
      jamis.speak(room, "anybody home?")

      david.enter(room)
      david.speak(room, "hello!")
    end

    private

      module CustomAssertions
        def enter(room)
          # reference a named route, for maximum internal consistency!
          get(room_url(:id => room.id))
          assert(...)
          ...
        end

        def speak(room, message)
          xml_http_request "/say/#{room.id}", :message => message
          assert(...)
          ...
        end
      end

      def login(who)
        open_session do |sess|
          sess.extend(CustomAssertions)
          who = people(who)
          sess.post "/login", :username => who.username,
            :password => who.password
          assert(...)
        end
      end
  end
Methods
Public Instance methods
method_missing(sym, *args, &block)

Delegate unhandled messages to the current session instance.

     # File vendor/rails/actionpack/lib/action_controller/integration.rb, line 545
545:     def method_missing(sym, *args, &block)
546:       reset! unless @integration_session
547:       returning @integration_session.send(sym, *args, &block) do
548:         copy_session_variables!
549:       end
550:     end
open_session() {|session if block_given?| ...}

Open a new session instance. If a block is given, the new session is yielded to the block before being returned.

  session = open_session do |sess|
    sess.extend(CustomAssertions)
  end

By default, a single session is automatically created for you, but you can use this method to open multiple sessions that ought to be tested simultaneously.

     # File vendor/rails/actionpack/lib/action_controller/integration.rb, line 514
514:     def open_session
515:       session = Integration::Session.new
516: 
517:       # delegate the fixture accessors back to the test instance
518:       extras = Module.new { attr_accessor :delegate, :test_result }
519:       self.class.fixture_table_names.each do |table_name|
520:         name = table_name.tr(".", "_")
521:         next unless respond_to?(name)
522:         extras.send(:define_method, name) { |*args| delegate.send(name, *args) }
523:       end
524: 
525:       # delegate add_assertion to the test case
526:       extras.send(:define_method, :add_assertion) { test_result.add_assertion }
527:       session.extend(extras)
528:       session.delegate = self
529:       session.test_result = @_result
530: 
531:       yield session if block_given?
532:       session
533:     end
reset!()

Reset the current session. This is useful for testing multiple sessions in a single test case.

     # File vendor/rails/actionpack/lib/action_controller/integration.rb, line 489
489:     def reset!
490:       @integration_session = open_session
491:     end