使用 Faraday 和 Rspec 进行存根

我有一个看起来像这样的模型：

class Gist
    def self.create(options)
    post_response = Faraday.post do |request|
      request.url 'https://api.github.com/gists'
      request.headers['Authorization'] = "Basic " + Base64.encode64("#{GITHUB_USERNAME}:#{GITHUB_PASSWORD}")
      request.body = options.to_json
    end
  end
end

和一个如下所示的测试：

require 'spec_helper'

describe Gist do
  context '.create' do
    it 'POSTs a new Gist to the user\'s account' do
      Faraday.should_receive(:post)
      Gist.create({:public => 'true',
                   :description => 'a test gist',
                   'files' => {'test_file.rb' => 'puts "hello world!"'}})
    end
  end
end

不过，这个测试并不能真正令我满意，因为我正在测试的只是用 Faraday 进行一些 POST，但我实际上无法测试 URL、标头或正文，因为它们是通过一个块。我尝试使用 Faraday 测试适配器，但我也没有看到任何测试 URL、标头或正文的方法。

有没有更好的方法来编写我的 Rspec 存根？或者我是否能够以某种我无法理解的方式使用法拉第测试适配器？

Thanks!

我的朋友@n1kh1l 向我指出了and_yieldRspec 方法和这个帖子 https://stackoverflow.com/questions/12641631/rspec-use-test-double-as-block-argument这让我可以像这样编写测试：

require 'spec_helper'

describe Gist do
  context '.create' do
    it 'POSTs a new Gist to the user\'s account' do
      gist = {:public => 'true',
              :description => 'a test gist',
              :files => {'test_file.rb' => {:content => 'puts "hello world!"'}}}

      request = double
      request.should_receive(:url).with('https://api.github.com/gists')
      headers = double
      headers.should_receive(:[]=).with('Authorization', "Basic " + Base64.encode64("#{GITHUB_USERNAME}:#{GITHUB_PASSWORD}"))
      request.should_receive(:headers).and_return(headers)
      request.should_receive(:body=).with(gist.to_json)
      Faraday.should_receive(:post).and_yield(request)

      Gist.create(gist)
    end
  end
end