rspec+rest-client测试第三方web service

如果你手工测试Restful 服务将会是一件非常单调乏味的事情。当然，目前有一些浏览器插件可以通过可视化的界面帮助你手工测试，例如postman、rest console，但是每次系统版本更新，你都需要去手动执行大量的测试，显然这种方式不是非常实用。Ruby拥有许多出色的gem包，你可以使用它们完成这项枯燥的工作。其中RestClient是我比较喜欢的一个。结合ruby的rspec框架使用RestClient可以编写非常强大的测试脚本。假如Github想让你测试他们的Restful API。你可能想做的第一件事就是确保端点返回你预计的响应代码。开始前，你需要确认你已经安装了相应的gems。 最便利的方式是使用bundler安装：

 source "https://rubygems.org"
 
 gem 'rest-client'
 gem 'rspec'
 gem 'json_expressions'

在cmd(windows，linux/mac环境请自行解决)进入你创建gemfile文件的同层目录，运行 'bundle'命令

 rafs-computer:rafael$ bundle
 Using diff-lcs 1.2.5
 Using json_expressions 0.8.3
 Using mime-types 2.3
 Using netrc 0.7.7
 Using rest-client 1.7.2
 Using rspec-support 3.1.1
 Using rspec-core 3.1.4
 Using rspec-expectations 3.1.2
 Using rspec-mocks 3.1.2
 Using rspec 3.1.0
 Using bundler 1.7.3
 Your bundle is complete!

现在让我们来验证我们从用户终端得到200响应：

 require 'rspec'
 require 'rest_client'
 
 describe 'GitHub API' do
 
     it 'should return information about a user' do
         result = RestClient.get 'https://api.github.com/users/rest-client',  :content_type => :json, :accept => :json
         expect(result.code).to eq(200)
     end
 
 end

在命令行执行rspec -f doc filename

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因此返回码是对的，但是我们如何知道返回的json也是对的呢？

有几种不同的方式去验证。一种方法是解析body中的json(由key,value组成)，然后针对你要检查的每个key创建断言。这种方式可以使用，但是它需要你写多个断言而且是比较难于维护的。另外一种方法是和一个已知有效的json格式的数据文件比较。你可以使用json_expressions gem包去做这个事情。下面的例子是相同的spec文件。新增一个testcase用来验证json数据。

首先准备一个users.json文件

 {
   "login": "rest-client",
   "id": 2386701,
   "avatar_url": "https://avatars.githubusercontent.com/u/2386701?v=3",
   "gravatar_id": "",
   "url": "https://api.github.com/users/rest-client",
   "html_url": "https://github.com/rest-client",
   "followers_url": "https://api.github.com/users/rest-client/followers",
   "following_url": "https://api.github.com/users/rest-client/following{/other_user}",
   "gists_url": "https://api.github.com/users/rest-client/gists{/gist_id}",
   "starred_url": "https://api.github.com/users/rest-client/starred{/owner}{/repo}",
   "subscriptions_url": "https://api.github.com/users/rest-client/subscriptions",
   "organizations_url": "https://api.github.com/users/rest-client/orgs",
   "repos_url": "https://api.github.com/users/rest-client/repos",
   "events_url": "https://api.github.com/users/rest-client/events{/privacy}",
   "received_events_url": "https://api.github.com/users/rest-client/received_events",
   "type": "Organization",
   "site_admin": false,
   "name": "REST-Client Team",
   "company": null,
   "blog": "",
   "location": null,
   "email": null,
   "hireable": false,
   "bio": null,
   "public_repos": 1,
   "public_gists": 0,
   "followers": 0,
   "following": 0,
   "created_at": "2012-09-20T15:01:43Z",
   "updated_at": "2015-03-11T19:08:01Z"
 }

然后编写测试用例spec文件

 require 'rspec'
 require 'rest_client'
 require 'json_expressions/rspec'
 
 describe 'GitHub API' do
 
   it 'should return 200 when asking information about a user' do
     result = RestClient.get 'https://api.github.com/users/rest-client',  :content_type => :json, :accept => :json
     expect(result.code).to eq(200)
   end
 
   it 'should return proper data for a user' do
     expected_data = JSON.parse(IO.read('users.json'))
     result = RestClient.get 'https://api.github.com/users/rest-client',  :content_type => :json, :accept => :json
     expect(result).to match_json_expression(expected_data)
   end
 
 end

这个users.json文件包含了一个已知的响应。正如你可能猜到了,一些这样的服务返回值可以改变很快。例如，"updated_at"是返回值可能经常变化的key。假如你只是想要验证key是否存在，而不关心它的值，你可以增加如下的代码到你的测试用例中。

   it 'should return proper data for a user' do
     expected_data = JSON.parse(IO.read('users.json')) #解析users.json文件中的数据作为预期值
     result = RestClient.get 'https://api.github.com/users/rest-client',  :content_type => :json, :accept => :json
     # expect(result).to match_json_expression(expected_data)
     expected_data['updated_at'] = wildcard_matcher
   end

想要了解更多关于json_expression gem的技巧，猛击github wiki page。