Micropost tests

現在要為 Microposts controller 寫一個簡短測試檢查權限，以及一個整合測試檢查整個操作流程。

首先我們要在 fixtures 裡增加不同的使用者發表的貼文（現在只需要一個，但還是多增加幾個，為以後備用）：

test/fixtures/microposts.yml

.
.
.
ants:
  content: "Oh, is that what you want? Because that's how you get ants!"
  created_at: <%= 2.years.ago %>
  user: archer

zone:
  content: "Danger zone!"
  created_at: <%= 3.days.ago %>
  user: archer

tone:
  content: "I'm sorry. Your words made sense, but your sarcastic tone did not."
  created_at: <%= 10.minutes.ago %>
  user: lana

van:
  content: "Dude, this van's, like, rolling probable cause."
  created_at: <%= 4.hours.ago %>
  user: lana

接著就來寫個簡短測試，確保某個使用者無法刪除其他使用者的貼文，以及檢查是否有導向正確的 URL：

test/controllers/microposts_controller_test.rb

require 'test_helper'

class MicropostsControllerTest < ActionController::TestCase

  def setup
    @micropost = microposts(:orange)
  end

  test "should redirect create when not logged in" do
    assert_no_difference 'Micropost.count' do
      post :create, micropost: { content: "Lorem ipsum" }
    end
    assert_redirected_to login_url
  end

  test "should redirect destroy when not logged in" do
    assert_no_difference 'Micropost.count' do
      delete :destroy, id: @micropost
    end
    assert_redirected_to login_url
  end

  test "should redirect destroy for wrong micropost" do
    log_in_as(users(:michael))
    micropost = microposts(:ants)
    assert_no_difference 'Micropost.count' do
      delete :destroy, id: micropost
    end
    assert_redirected_to root_url
  end
end

最後寫個整合測試，檢查 micropost 分頁，然後分別及提交有效和無效的資料，刪除貼文，最後瀏覽第二個使用者的頁面，確保沒有「delete」連結。

先建立一個整合測試文件：

$ rails generate integration_test microposts_interface
      invoke  test_unit
      create    test/integration/microposts_interface_test.rb

整合測試程式碼如下，看看能否把程式碼跟之前說的測試步驟對應起來：

test/integration/microposts_interface_test.rb

require 'test_helper'

class MicropostsInterfaceTest < ActionDispatch::IntegrationTest

  def setup
    @user = users(:michael)
  end

  test "micropost interface" do
    log_in_as(@user)
    get root_path
    assert_select 'div.pagination'
    # Invalid submission
    assert_no_difference 'Micropost.count' do
      post microposts_path, micropost: { content: "" }
    end
    assert_select 'div#error_explanation'
    # Valid submission
    content = "This micropost really ties the room together"
    assert_difference 'Micropost.count', 1 do
      post microposts_path, micropost: { content: content }
    end
    assert_redirected_to root_url
    follow_redirect!
    assert_match content, response.body
    # Delete a post.
    assert_select 'a', text: 'delete'
    first_micropost = @user.microposts.paginate(page: 1).first
    assert_difference 'Micropost.count', -1 do
      delete micropost_path(first_micropost)
    end
    # Visit a different user.
    get user_path(users(:archer))
    assert_select 'a', text: 'delete', count: 0
  end
end

這個測試中，post 請求後調用 follow_redirect!，而沒有直接使用 post_via_redirect，這是要兼顧之後的圖片上傳測試。

因為我們之前已經把應用程式碼寫好了，所以測試應該會通過（Green）：

$ bundle exec rake test