如何模拟呼叫开放 - uri

Question

我有一个使用'open-uri'的邮件程序。

require 'open-uri' 
class NotificationMailer < ActionMailer::Base 

    def welcome(picasa_picture) 
    picture = picasa_picture.content.src 
    filename = picture.split('/').last 
    attachments.inline[filename] = open(picture).read 
    mail(
     to: 'foo@exmample.com', 
     from: 'bar@example.com', 
     subject: 'hi', 
    ) 
    end 
end 

但是当我尝试和测试任何类，我得到这个错误：

SocketError: 
    getaddrinfo: nodename nor servname provided, or not known 

我发现这个职位的SO：How to rspec mock open-uri并认为这将帮助。我给了这个尝试：

let(:pic_content) { double(:pic_content, src: 'http://www.picasa/asdf/asdf.jpeg') } 
let(:picture) { double(:picture, content: pic_content) } 
let(:open_uri_mock) { double(:uri_mock, read: true) } 

subject { described_class.welcome(picture) } 

it 'renders email address of sender' do 
    subject.stub(:open).and_return(open_uri_mock) 
    subject.from.should == [ sender_address ] 
end 

我也尝试了'should_receive'而不是'存根'，但它没有帮助。如何禁止open-uri'open'方法，使其（1）不会尝试去互联网和（2）不打破我的测试？

Answer 1

为什么不重构：

require 'open-uri' 
class NotificationMailer < ActionMailer::Base 

    def welcome(picasa_picture) 
    picture = picasa_picture.content.src 
    filename = picture.split('/').last 
    attachments.inline[filename] = open_and_read(picture) 
    mail(
     to: 'foo@exmample.com', 
     from: 'bar@example.com', 
    subject: 'hi', 
    ) 
    end 

    def open_and_read(picture) 
    open(picture).read 
    end 

end 

然后你可以存根和测试：

subject { NotificationMailer } 

before do 
    subject.stub(:open_and_read).and_return(:whatever_double_you_want) 
    subject.welcome(picture) 
end 

it 'renders email address of sender' do 
    subject.from.should == [ sender_address ] 
end