Day21 测试写起乃 - Webmock

在写测试的时後，一定会有第三方服务或是会打向外部api的时候，如果不想让他真的去打外部api怕速度过慢的等等问题就可以使用 webmock 。

webmock 可以伪装 HTTP 来确保我们在测试时不会真的发出请求。

安装 webmock

# add to your Gemfile
group :test do
    gem "webmock"
end

# spec_helper.rb

require 'webmock/rspec'
WebMock.disable_net_connect!(allow_localhost: true)

参考范例：

在还没有禁用 api 之前会通过

    context "get github api" do
      it 'repo on GitHub' do
      uri = URI('https://api.github.com/repositories')

      response = Net::HTTP.get(uri)
        
      expect(response).to be_an_instance_of(String)
      end
    end

如果在测试之前加上

  before(:all) { WebMock.disable_net_connect! }
  after(:all) { WebMock.allow_net_connect! }
  
  context "get github api" do
    it 'repo on GitHub' do
    uri = URI('https://api.github.com/repositories')

    response = Net::HTTP.get(uri)

    expect(response).to be_an_instance_of(String)
    end
  end

此时会出现贴心的错误提示告诉你该如果撰写

 Failure/Error: response = Net::HTTP.get(uri)

 WebMock::NetConnectNotAllowedError:
   Real HTTP connections are disabled. Unregistered request: GET https://api.github.com/repositories with headers {'Accept'=>'*/*', 'Accept-Encoding'=>'gzip;q=1.0,deflate;q=0.6,identity;q=0.3', 'Host'=>'api.github.com', 'User-Agent'=>'Ruby'}

   You can stub this request with the following snippet:

   stub_request(:get, "https://api.github.com/repositories").
     with(
       headers: {
      'Accept'=>'*/*',
      'Accept-Encoding'=>'gzip;q=1.0,deflate;q=0.6,identity;q=0.3',
      'Host'=>'api.github.com',
      'User-Agent'=>'Ruby'
       }).
     to_return(status: 200, body: "", headers: {})

这时来修改一下

  context "github api" do
    it 'repo on GitHub' do
    uri = URI('https://api.github.com/repositories')

    stub_request(:get, uri).
    with(
      headers: {
      'Accept'=>'*/*',
      'Accept-Encoding'=>'gzip;q=1.0,deflate;q=0.6,identity;q=0.3',
      'Host'=>'api.github.com',
      'User-Agent'=>'Ruby'
      }).
    to_return(status: 200, body: "", headers: {})

    response = Net::HTTP.get(uri)

    expect(response).to be_an_instance_of(String)
    end
  end

这时确实已经将 api stub 了，且测试也会通过

参考来源：
WebMock
How to Stub External Services in Tests