testing services effectively

TESTING SERVICESeffectively

Alberto Leal @albertoleal

http://albertoleal.me

What is a service?

ExternalService

Internal Service

ad$

A

http://api.example.com/cars

Request Response

Connection: keep-aliveContent-Length: 1466Content-Type: application/json; Date: Sat, 02 Aug 2014 19:42:38 GMTETag: W/"5ba-70348105"

{ "cars": [ { "created": "2014-07-25T19:27:56.919Z", "id": "53d2afbc7165355f0eaf79da", "modified": "2014-07-25T19:27:56.919Z", "name": "Ferrari" }, { "created": "2014-07-25T19:27:56.874Z", "id": "53d2afbc7165355f0eaf79d9", "modified": "2014-07-25T19:27:56.874Z", "name": "Porshe" } ]}

Request Response

http://api.example.com/cars

Connection: keep-aliveContent-Length: 1466Content-Type: application/json; Date: Sat, 02 Aug 2014 19:42:38 GMTETag: W/"5ba-70348105"

{ "cars": [ { "created": "2014-07-25T19:27:56.919Z", "id": "53d2afbc7165355f0eaf79da", "modified": "2014-07-25T19:27:56.919Z", "name": "Ferrari" }, { "created": "2014-07-25T19:27:56.874Z", "id": "53d2afbc7165355f0eaf79d9", "modified": "2014-07-25T19:27:56.874Z", "name": "Porshe" } ]}

headers

Connection: keep-aliveContent-Length: 1466Content-Type: application/json; Date: Sat, 02 Aug 2014 19:42:38 GMTETag: W/"5ba-70348105"

{ "cars": [ { "created": "2014-07-25T19:27:56.919Z", "id": "53d2afbc7165355f0eaf79da", "modified": "2014-07-25T19:27:56.919Z", "name": "Ferrari" }, { "created": "2014-07-25T19:27:56.874Z", "id": "53d2afbc7165355f0eaf79d9", "modified": "2014-07-25T19:27:56.874Z", "name": "Porshe" } ]}

body

Failures:!

1) Car Service should retrieve all cars Failure/Error: response = RestClient.get ‘api.example.com/cars' SocketError: getaddrinfo: nodename nor servname provided, or not known # ./test_spec.rb:12:in `block (2 levels) in <top (required)>'!

Finished in 0.02436 seconds (files took 0.81924 seconds to load)1 example, 1 failure!

Failed examples:!

rspec ./test_spec.rb:11 # External Service should retrieve all cars

gem 'webmock'

https://github.com/bblimke/webmock

require 'webmock/rspec'require 'rest_client'!

describe 'Car Service’ do it 'should retrieve all cars' do response = RestClient.get ‘api.example.com/cars' expect(response).to be_an_instance_of(String) endend

------------------------------ FAIL: 1 PASS: 0 PENDING: 0------------------------------Finished in 0.04571 seconds [Car Service]- should retrieve all cars Real HTTP connections are disabled. Unregistered request: GET http://api.example.com/cars with headers {'Accept'=>'*/*; q=0.5, application/xml', 'Accept-Encoding'=>'gzip, deflate', 'User-Agent'=>'Ruby'}You can stub this request with the following snippet:stub_request(:get, “http://api.example.com/cars”). with(:headers => {'Accept'=>'*/*; q=0.5, application/xml', 'Accept-Encoding'=>'gzip, deflate', 'User-Agent'=>'Ruby'}). to_return(:status => 200, :body => "", :headers => {})

require 'webmock/rspec'require 'rest_client'!

WebMock.allow_net_connect!!

describe 'Car Service' do it 'should retrieve all cars' do response = RestClient.get ‘api.example.com/cars' expect(response).to be_an_instance_of(String) endend

require 'webmock/rspec'require 'rest_client'!

# WebMock.allow_net_connect!!

describe 'Car Service' do before :all do stub_request(:get, ‘api.example.com/cars') .to_return(status: 200, headers: {}, body: 'This is a mock.') end!

it 'should retrieve all cars' do response = RestClient.get ‘http://api.example.com/cars' expect(response).to eq(‘This is a mock.') endend

gem 'vcr'gem 'vcr'

https://github.com/vcr/vcr

ENV["RAILS_ENV"] ||= 'test'require File.expand_path("../../config/environment", __FILE__)require 'rspec/rails'require 'rspec/autorun'!

RSpec.configure do |config| config.mock_with :rspec config.infer_base_class_for_anonymous_controllers = false config.order = "random"!

#Configuring VCR gem config.around(:each, :vcr) do |example| opts = example.metadata.slice(:record, :match_requests_on).except(:example_group) VCR.use_cassette(example.metadata[:cassette_name], opts) { example.call } endend

describe Car do ... describe '.all' do it 'should retrieve all available cars', :vcr, cassette_name: ‘cars/all’ do cars = Car.all expect(cars).to be_an_instance_of Array expect(cars).to have(2).items end end!

...end

gem 'puffing-billy'

https://github.com/oesmith/puffing-billy

require ‘billy/rspec'!

Capybara.javascript_driver = :selenium_billy

proxy.stub(‘http://api.example.com/cars').and_return(json: {cars: […]})

IntegrationTests

Contract Tests

Consumer-Driven Contracts: A Service Evolution Pattern

http://martinfowler.com/articles/consumerDrivenContracts.html

Contracts can couple

service providers and

consumers

gem 'pact'

https://github.com/realestate-com-au/pact

class MyServiceProviderClient include HTTParty base_uri 'http://my-service'!

def get_something name = JSON.parse(self.class.get("/something").body)['name'] Something.new(name) endend

Client

require 'pact/consumer/rspec'!

Pact.service_consumer "My Service Consumer" do has_pact_with "My Service Provider" do mock_service :my_service_provider do port 1234 end endend

Mock Server

describe MyServiceProviderClient, pact: true do! before do # Configure your client to point to the stub service on localhost using the port you have specified MyServiceProviderClient.base_uri 'localhost:1234' end! subject { MyServiceProviderClient.new }! describe "get_something" do! before do my_service_provider.given("something exists"). upon_receiving("a request for something").with(method: :get, path: '/something'). will_respond_with( status: 200, headers: {'Content-Type' => 'application/json'}, body: {name: 'A small something'} ) end! it "returns a Something" do expect(subject.get_something).to eq(Something.new('A small something')) end! end!end

thanks!http://albertoleal.me

https://www.flickr.com/photos/robsmits/5452184206

https://www.flickr.com/photos/hotcherry/521006473

Photos:

https://www.flickr.com/photos/vern/5379218273/sizes/l