Testing Services Effectively with Ruby

1. TESTING SERVICES
effectively
Alberto Leal @albertoleal

2. http://albertoleal.me

4. What is a service?

5. External
Service
Internal
Service

6. ad$
A

7. http://api.example.com/cars
Request Response

8. Connection: keep-alive
Content-Length: 1466
Content-Type: application/json;
Date: Sat, 02 Aug 2014 19:42:38 GMT
ETag: 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

9. Connection: keep-alive
Content-Length: 1466
Content-Type: application/json;
Date: Sat, 02 Aug 2014 19:42:38 GMT
ETag: 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

10. Connection: keep-alive
Content-Length: 1466
Content-Type: application/json;
Date: Sat, 02 Aug 2014 19:42:38 GMT
ETag: 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

12. 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

13. gem 'webmock'
https://github.com/bblimke/webmock

14. 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)
end
end

15. ------------------------------
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 => {})

16. 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)
end
end

18. 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.')
end
end

19. gem 'vcr'gem 'vcr'
https://github.com/vcr/vcr

20. 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 }
end
end

21. 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

22. gem 'puffing-billy'
https://github.com/oesmith/puffing-billy

23. require ‘billy/rspec'
!
Capybara.javascript_driver = :selenium_billy

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

25. Integration
Tests
Contract
Tests

26. Consumer-Driven Contracts:
A Service Evolution Pattern
http://martinfowler.com/articles/consumerDrivenContracts.html

28. Contracts can couple
service providers
and
consumers

34. gem 'pact'
https://github.com/realestate-com-au/pact

35. class MyServiceProviderClient
include HTTParty
base_uri 'http://my-service'
!
def get_something
name = JSON.parse(self.class.get("/something").body)['name']
Something.new(name)
end
end
Client

36. 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
end
end
Mock Server

37. 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

38. thanks!
http://albertoleal.me

39. https://www.flickr.com/photos/robsmits/5452184206
https://www.flickr.com/photos/hotcherry/521006473
Photos:
https://www.flickr.com/photos/vern/5379218273/sizes/l