如何在控制器測試中使用簡單的測試間諜？

Question

我想測試我的控制器只是調用服務對象的方法。我認爲一個測試間諜會是完美的。我究竟做錯了什麼？謝謝你的幫助！

控制器：

class PostsController < ApplicationController 

    def create 
    @post = Post.new(post_params) 

    if @post.save 
     ServiceObject.new(@post).call 
     redirect_to posts_path, success: "#{@post.title} was successfully created." 
    else 
     render action: :new 
    end 
    end 

end 

服務對象：

class ServiceObject 

    def initialize(post) 
    @post = post 
    end 

    def call 
    puts "Service object was called!" 
    end 

end 

控制器測試：

require 'spec_helper' 

describe PostsController do 
    describe 'POST #create' do 
    it 'calls the service object' do 
     service_object = double(ServiceObject) 
     service_object.stub(:new).and_return(service_object) 
     service_object.stub(:call) 
     post :create, post: Fabricate.attributes_for(:post) 
     expect(service_object).to have_received(:call) 
    end 
    end 
end 

錯誤：

Failure/Error: expect(service_object).to have_received(:call) 
    (Double ServiceObject).call(any args) 
     expected: 1 time with any arguments 
     received: 0 times with any arguments 

Answer 1

試試這個：

require 'spec_helper' 

describe PostsController do 
    describe 'POST #create' do 
    let(:service_object) { double(:service_object) } 

    before do 
     ServiceObject.stub(:new).and_return(service_object) 
     service_object.stub(:call) 
    end 

    it 'calls the service object' do 
     post :create, post: Fabricate.attributes_for(:post) 

     expect(service_object).to have_received(:call) 
    end 
    end 
end