集成测试跨越多个控制器和操作，将它们全部连接在一起，以确保它们按预期一起工作。与单元测试或功能测试相比，它更完整地进行测试，从调度程序到数据库，对整个堆栈进行测试。

最简单的方法是扩展 IntegrationTest 并使用 Integration::RequestHelpers#get 和/或 Integration::RequestHelpers#post 方法编写测试。

require "test_helper"

class ExampleTest < ActionDispatch::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", params: { username: people(:jamis).username,
      password: people(:jamis).password }
    follow_redirect!
    assert_equal 200, status
    assert_equal "/home", path
  end
end

但是，您也可以在每个测试中打开多个会话实例，甚至使用断言和方法扩展这些实例，以创建针对您的应用程序的非常强大的测试 DSL。

require "test_helper"

class AdvancedTest < ActionDispatch::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)
        post "/say/#{room.id}", xhr: true, params: { message: message }
        assert(...)
        ...
      end
    end

    def login(who)
      open_session do |sess|
        sess.extend(CustomAssertions)
        who = people(who)
        sess.post "/login", params: { username: who.username,
          password: who.password }
        assert(...)
      end
    end
end

另一个更长的示例将是

一个简单的集成测试，它练习多个控制器

require "test_helper"

class UserFlowsTest < ActionDispatch::IntegrationTest
  test "login and browse site" do
    # login via https
    https!
    get "/login"
    assert_response :success

    post "/login", params: { username: users(:david).username, password: users(:david).password }
    follow_redirect!
    assert_equal '/welcome', path
    assert_equal 'Welcome david!', flash[:notice]

    https!(false)
    get "/articles/all"
    assert_response :success
    assert_select 'h1', 'Articles'
  end
end

如您所见，集成测试涉及多个控制器，并从数据库到调度程序对整个堆栈进行测试。此外，您可以在测试中同时打开多个会话实例，并使用断言方法扩展这些实例，以专门为您的应用程序创建非常强大的测试 DSL（特定于域的语言）。

以下是集成测试中多个会话和自定义 DSL 的示例

require "test_helper"

class UserFlowsTest < ActionDispatch::IntegrationTest
  test "login and browse site" do
    # User david logs in
    david = login(:david)
    # User guest logs in
    guest = login(:guest)

    # Both are now available in different sessions
    assert_equal 'Welcome david!', david.flash[:notice]
    assert_equal 'Welcome guest!', guest.flash[:notice]

    # User david can browse site
    david.browses_site
    # User guest can browse site as well
    guest.browses_site

    # Continue with other assertions
  end

  private

    module CustomDsl
      def browses_site
        get "/products/all"
        assert_response :success
        assert_select 'h1', 'Products'
      end
    end

    def login(user)
      open_session do |sess|
        sess.extend(CustomDsl)
        u = users(user)
        sess.https!
        sess.post "/login", params: { username: u.username, password: u.password }
        assert_equal '/welcome', sess.path
        sess.https!(false)
      end
    end
end

有关如何使用 get 等的帮助，请参阅 [请求帮助程序文档] (ActionDispatch::Integration::RequestHelpers)。

更改请求编码

您还可以通过设置请求应编码的方式来轻松测试您的 JSON API

require "test_helper"

class ApiTest < ActionDispatch::IntegrationTest
  test "creates articles" do
    assert_difference -> { Article.count } do
      post articles_path, params: { article: { title: "Ahoy!" } }, as: :json
    end

    assert_response :success
    assert_equal({ id: Article.last.id, title: "Ahoy!" }, response.parsed_body)
  end
end

as 选项传递一个“application/json” Accept 标头（从而将请求格式设置为 JSON，除非被覆盖），将内容类型设置为“application/json” 并将参数编码为 JSON。

在响应上调用 TestResponse#parsed_body 会根据最后一个响应 MIME 类型解析响应主体。

开箱即用，只支持 :json。但是，对于您注册的任何自定义 MIME 类型，您可以使用以下方法添加自己的编码器：

ActionDispatch::IntegrationTest.register_encoder :wibble,
  param_encoder: -> params { params.to_wibble },
  response_parser: -> body { body }

其中 param_encoder 定义了如何编码参数，response_parser 定义了如何通过 TestResponse#parsed_body 解析响应主体。

有关更多信息，请参阅 Rails 测试指南。