為什么我的Rspec測試失敗？

Question

我正在編寫一個小的Rails todo應用程序進行練習。 我正在嘗試為各種事情編寫自己的Rspec測試，而不僅僅是遵循教程。 我只有幾個測試，但有幾個失敗了，我不知道為什么。 我盡力使在這里發布問題成為最后的選擇，但是每次我在這里提出問題時，我都可以很好地解決我的問題。

這是一些代碼：

require 'spec_helper'

describe "TodosPages" do
  describe "home page" do
before { visit root_path }

it "should have the content 'Todo App'" do      
    page.should have_content('Todo App')
end  
it "should have title tag" do       
    page.should have_selector 'title'
end  
  it "should delete a todo and redirect to index" do    
      expect { click_link "Delete last todo" }.to change(Todo, :count).by(-1)
      response.should redirect_to :action => 'index'
  end
 describe "Add Todo" do
  subject { page }
   before {click_button "Add todo"}
   it { should have_selector('div.alert.alert-success', text: 'Todo Successfully Created') }

  end

  it "should have a error message" do
    pending
  end

  it "should create a Todo" do
   expect { click_button "Add todo" }.to change(Todo, :count).by(1)
  end


 end

end

---

 todos_controller



  class TodosController < ApplicationController
  def index
    @todo_items = Todo.all
    @new_todo = Todo.new
    render :index

  end

  def delete
    @todo_delete = Todo.last
    @todo_delete.delete
    redirect_to :action => 'index'

  end

   def add
   todo = Todo.create(:todo_item => params[:todo][:todo_item])
   unless todo.valid?
     flash[:error] = todo.errors.full_messages.join("<br>").html_safe
   else
     flash[:success] = "Todo Successfully Created"  
   end
  redirect_to :action => 'index'
end

def complete
    params[:todos_checkbox].each do |check|
       todo_id = check
       t = Todo.find_by_id(todo_id)
       t.update_attribute(:completed, true)
     end
     redirect_to :action => 'index'
    end
  end

---

   index.html.erb

<% @title = "Todo App" %>
<div class="container"> 
    <div class="row">
     <div class='span6' >

      <h1 class="hero-unit">Simple Todo App</h1>


      <p>All your todos here</p>
            <%= form_for @new_todo, :url => { :action => "add" }  do |f|  %>
            <%= f.text_field  :todo_item %>
            <%= f.submit "Add todo", class: "btn btn-primary" %>
         <%end%>

            <% if flash[:error] %>
             <div class="alert alert-error">
                <button type="button" class="close" data-dismiss="alert" >×</button>
                <strong><%= flash[:error] %></strong>
                </div>
            <% end %>

            <% if flash[:success] %>
           <div class="alert alert-success">
             <button type="button" class="close" data-dismiss="alert" >×</button>
                <strong><%= flash[:success] %></strong>
           </div>
      <% end %>

<div class="well">
    <%= form_tag("/todos/complete/", :method => "post") do %>
        <ul style="list-style-type:none;">
        <% @todo_items.each do |t| %> 
         <% if t.completed == true %>
         <li style="color:grey;"> <%= check_box_tag  "todos_checkbox[]",t.id %>  <strike><%= t.todo_item %></strike> </li>
      <% else %>
         <li> <%= check_box_tag  "todos_checkbox[]",t.id %> <%= t.todo_item %> </li>
      <% end %>
            <%end%>
            </ul>
                <%= submit_tag("Complete Todos", :class=>"btn btn-success") %>
            <%end %>
        </div> <!-- well --> 
        <%=  link_to "Delete last todo", delete_path %>

    </div> <!-- span6--> 
 </div> <!-- row --> 

  Failures:

 1) TodosPages home page should create a Todo
 Failure/Error: expect { click_button "Add todo" }.to change(Todo, :count).by(1)
   count should have been changed by 1, but was changed by 0
 # ./spec/views/index_page_spec.rb:29:in `block (3 levels) in <top (required)>'

 2) TodosPages home page should delete a todo and redirect to index
 Failure/Error: expect { click_link "Delete last todo" }.to change(Todo, :count).by(-1)
 NoMethodError:
   undefined method `delete' for nil:NilClass
 # ./app/controllers/todos_controller.rb:11:in `delete'
 # (eval):2:in `click_link'
 # ./spec/views/index_page_spec.rb:14:in `block (4 levels) in <top (required)>'
 # ./spec/views/index_page_spec.rb:14:in `block (3 levels) in <top (required)>'

 3) TodosPages home page Add Todo 
 Failure/Error: it { should have_selector('div.alert.alert-success', text: 'Todo Successfully   Created') }
   expected css "div.alert.alert-success" with text "Todo Successfully Created" to return something
 # ./spec/views/index_page_spec.rb:20:in `block (4 levels) in <top (required)>'

 Finished in 0.33114 seconds
 8 examples, 3 failures, 1 pending

 Failed examples:

 rspec ./spec/views/index_page_spec.rb:28 # TodosPages home page should create a Todo
 rspec ./spec/views/index_page_spec.rb:13 # TodosPages home page should delete a todo and redirect to index
 rspec ./spec/views/index_page_spec.rb:20 # TodosPages home page Add Todo 

 Randomized with seed 32260

提前致謝！

------ Todo.rb

---

 class Todo < ActiveRecord::Base
    attr_accessible :todo_item, :completed
    validates :todo_item, presence: true , length: { maximum: 25 }

    end

Answer 1

我會為此刺一針。 沒有特別的順序：

測試2（TodosPages主頁應刪除待辦事項並重定向到索引）

看來您的Todo表在測試數據庫中為空，因此在控制器操作中調用Todo.last時，您得到nil，然后嘗試對nil調用delete。

在刪除測試之前，您在測試中的任何地方看不到要創建至少一個Todo對象的地方。

另外，在控制器中，您可能需要考慮使用destroy而不是delete方法。

測試1（TodosPages主頁應創建一個待辦事項）

在驗證方面，您的Todo模型中有什么？ 是否有任何必填字段？ 我猜測：todo_item是必填字段，但是在您的rspec測試中，您只需單擊按鈕，並且不為該字段提供任何輸入，因此它可能無法通過模型驗證。

在要添加的控制器操作中，使用create！ 而不是創建，如果模型驗證失敗，應該會給您其他錯誤消息。

測試3（TodosPages主頁添加Todo）

可能由於上述測試失敗的相同原因而失敗，即驗證失敗。 首先解決該問題，然后查看此測試是否通過。

希望這可以幫助。

編輯：通過參數的測試示例

我個人的喜好是將控制器測試（測試特定的控制器功能）與集成類型測試（確保頁面正確填充，按鈕出現且可單擊等）分開。 對於后者，我喜歡使用黃瓜。 然后，您可以使用Rspec編寫一些簡單得多的Controller測試，從而可以測試特定的邏輯並將參數直接傳遞給要測試的動作。 測試看起來像

describe "add Todo" do
 it "increases count by 1" do 
  expect {post: :add, todo_item: "string"}.to change(Todo, :count).by(1)
 end
end

另外，如果您想繼續在Rspec中進行集成測試（假設您使用Capybara模擬瀏覽器），則需要為todo_item文本字段賦予唯一的ID或名稱，然后可以執行以下操作：

it "should create a Todo" do
 fill_in "*todo_item_unique_id" with "some text"
 expect { click_button "Add todo" }.to change(Todo, :count).by(1)
end