Effectively

Testing

ServicesNeal Kemp

$ whoami

Iowa native

Now: Californian

Software Developer

Independent Consultant

What I Do

Ruby / Rails

Javascript / Angular

HTML, CSS, etc

what, why & howof testing services

NOT Building testable services

NOT Test-driven development

(necessarily)

… and because I don’t want @dhh to rage

what

What is a service?

Internal “SOA”

Any time you make an HTTP

request to an endpoint in

another repository

why

Why are services important?

Build faster

Makes scaling easier

Use them on virtually every application

Increasingly prevalent

Services are critical to

modern Rails

development

Why is testing services

important?You (should) test everything else

Services compose crucial features

You may encounter problems…

Internal API

Sometimes null responses

Inconsistencies

Catastrophe

Okay? But what about external APIs?

{"id": 24}

{"code": "ANA"}

"goals":[

{

"per":"1",

"ta":"CGY",

"et":"14:11",

"st":"Wrist Shot"

},

{

"per":"2",

"ta":"ANA",

"et":"11:12",

"st":"Backhand"

}

]

"goals": {

"per":"1",

"ta":"CGY",

"et":"14:11",

"st":"Wrist Shot"

}

No versioning!

Snapchat Client

Haphazard documentation

What are the requests?

Bizarre obfuscation

github.com/nneal/snapcat

how

What is different about

services?External network requests

You don’t own the code

On an airplane…

Failure is bad!

No network requests

Don’t interact with services from

test environment* **

* Includes “dummy” APIs

** Using pre-recorded

responses is okay

Assuming:

Rails, rspec

Time to stub!

Built-in Stubbing

Typhoeus

Faraday

Excon

Simplify.

gem 'webmock'

ENV['RAILS_ENV'] ||= 'test'

require File.expand_path('../../config/environment', __FILE__)

require 'rspec/autorun'

require 'rspec/rails’

Dir[Rails.root.join("spec/support/**/*.rb")].each { |f| require f }

ActiveRecord::Migration.check_pending! if defined?(ActiveRecord::Migration)

RSpec.configure do |config|

config.infer_base_class_for_anonymous_controllers = false

config.order = 'random’

end

WebMock.disable_net_connect!

spec/spec_helper.rb

module FacebookWrapper

def self.user_id(username)

user_data(username)['id']

end

def self.user_data(username)

JSON.parse(

open("https://graph.facebook.com/#{username}").read

)

end

end

lib/facebook_wrapper.rb

require 'facebook_wrapper'

config/intializers/facebook_wrapper.rb

require 'spec_helper'

describe FacebookWrapper, '.user_link' do

it 'retrieves user link' do

stub_request(:get, 'https://graph.facebook.com/arjun').

to_return(

status: 200,

headers: {},

body: '{

"id": "7901103","first_name": "Arjun",

"locale": "en_US","username": "Arjun"

}'

)

user_id = FacebookWrapper.user_id('arjun')

expect(user_id).to eq '7901103'

end

end

spec/lib/facebook_wrapper_spec.rb

require 'spec_helper'

describe FacebookWrapper, '.user_link' do

it 'retrieves user link' do

stub_request(:get, 'https://graph.facebook.com/arjun').

to_return(

status: 200,

headers: {},

body: '{

"id": "7901103","first_name": "Arjun",

"locale": "en_US","username": "Arjun"

}'

)

user_id = FacebookWrapper.user_id('arjun')

expect(user_id).to eq '7901103'

end

end

spec/lib/facebook_wrapper_spec.rb

require 'spec_helper'

describe FacebookWrapper, '.user_link' do

it 'retrieves user link' do

stub_request(:get, 'https://graph.facebook.com/arjun').

to_return(

status: 200,

headers: {},

body: '{

"id": "7901103","first_name": "Arjun",

"locale": "en_US","username": "Arjun"

}'

)

user_id = FacebookWrapper.user_id('arjun')

expect(user_id).to eq '7901103'

end

end

spec/lib/facebook_wrapper_spec.rb

require 'spec_helper'

describe FacebookWrapper, '.user_link' do

it 'retrieves user link' do

stub_request(:get, 'https://graph.facebook.com/arjun').

to_return(

status: 200,

headers: {},

body: '{

"id": "7901103","first_name": "Arjun",

"locale": "en_US","username": "Arjun"

}'

)

user_id = FacebookWrapper.user_id('arjun')

expect(user_id).to eq '7901103'

end

end

spec/lib/facebook_wrapper_spec.rb

Even Better

No network requests

Fast!

No intermittent failure

Mock-Services

AWS

FB graph mock

OmniAuth

Etc…

gem 'fb_graph-mock'

ENV['RAILS_ENV'] ||= 'test'

require File.expand_path('../../config/environment', __FILE__)

require 'rspec/autorun'

require 'rspec/rails’

require 'fb_graph/mock'

Dir[Rails.root.join("spec/support/**/*.rb")].each { |f| require f }

ActiveRecord::Migration.check_pending! if defined?(ActiveRecord::Migration)

RSpec.configure do |config|

config.infer_base_class_for_anonymous_controllers = false

config.order = 'random'

config.include FbGraph::Mock

end

WebMock.disable_net_connect!

spec/spec_helper.rb

describe FacebookWrapper, '.user_link' do

it 'retrieves user link' do

mock_graph :get, 'arjun', 'users/arjun_public' do

user_id = FacebookWrapper.user_id('arjun')

expect(user_id).to eq '7901103'

end

end

end

spec/lib/facebook_wrapper_spec.rb

describe FacebookWrapper, '.user_link' do

it 'retrieves user link' do

mock_graph :get, 'arjun', 'users/arjun_public' do

user_id = FacebookWrapper.user_id('arjun')

expect(user_id).to eq '7901103'

end

end

end

spec/lib/facebook_wrapper_spec.rb

Even Better

Already stubbed for you

Pre-recorded responses (sometimes)

Don’t need to know API endpoints

gem 'sham_rack'

gem 'sinatra'

ENV['RAILS_ENV'] ||= 'test'

require File.expand_path('../../config/environment', __FILE__)

require 'rspec/autorun'

require 'rspec/rails’

Dir[Rails.root.join("spec/support/**/*.rb")].each { |f| require f }

ActiveRecord::Migration.check_pending! if defined?(ActiveRecord::Migration)

RSpec.configure do |config|

config.infer_base_class_for_anonymous_controllers = false

config.order = 'random’

end

WebMock.disable_net_connect!

spec/spec_helper.rb

ShamRack.at('graph.facebook.com', 443).sinatra do

get '/:username' do

%Q|{

"id": "7901103",

"name": "Arjun Banker",

"first_name": "Arjun",

"last_name": "Banker",

"link": "http://www.facebook.com/#{params[:username]}",

"location": {

"id": 114952118516947,

"name": "San Francisco, California"

},

"gender": "male"

}|

end

end

spec/support/fake_facebook.rb

ShamRack.at('graph.facebook.com', 443).sinatra do

get '/:username' do

%Q|{

"id": "7901103",

"name": "Arjun Banker",

"first_name": "Arjun",

"last_name": "Banker",

"link": "http://www.facebook.com/#{params[:username]}",

"location": {

"id": 114952118516947,

"name": "San Francisco, California"

},

"gender": "male"

}|

end

end

spec/support/fake_facebook.rb

ShamRack.at('graph.facebook.com', 443).sinatra do

get '/:username' do

%Q|{

"id": "7901103",

"name": "Arjun Banker",

"first_name": "Arjun",

"last_name": "Banker",

"link": "http://www.facebook.com/#{params[:username]}",

"location": {

"id": 114952118516947,

"name": "San Francisco, California"

},

"gender": "male"

}|

end

end

spec/support/fake_facebook.rb

ShamRack.at('graph.facebook.com', 443).sinatra do

get '/:username' do

%Q|{

"id": "7901103",

"name": "Arjun Banker",

"first_name": "Arjun",

"last_name": "Banker",

"link": "http://www.facebook.com/#{params[:username]}",

"location": {

"id": 114952118516947,

"name": "San Francisco, California"

},

"gender": "male"

}|

end

end

spec/support/fake_facebook.rb

describe FacebookWrapper, '.user_link' do

it 'retrieves user link' do

user_id = FacebookWrapper.user_id('arjun')

expect(user_id).to eq '7901103’

end

end

spec/lib/facebook_wrapper_spec.rb

Even Better

Dynamic

Expressive

Readable

gem 'vcr'

ENV['RAILS_ENV'] ||= 'test'

require File.expand_path('../../config/environment', __FILE__)

require 'rspec/autorun'

require 'rspec/rails’

Dir[Rails.root.join("spec/support/**/*.rb")].each { |f| require f }

ActiveRecord::Migration.check_pending! if defined?(ActiveRecord::Migration)

RSpec.configure do |config|

config.infer_base_class_for_anonymous_controllers = false

config.order = 'random’

end

WebMock.disable_net_connect!

VCR.configure do |c|

c.cassette_library_dir = 'spec/fixtures/vcr_cassettes'

c.hook_into :webmock

end spec/spec_helper.rb

describe FacebookWrapper, '.user_link' do

it 'retrieves user link' do

VCR.use_cassette('fb_user_arjun') do

user_id = FacebookWrapper.user_id('arjun')

expect(user_id).to eq '7901103'

end

end

end

spec/lib/facebook_wrapper_spec.rb

describe FacebookWrapper, '.user_link' do

it 'retrieves user link' do

VCR.use_cassette('fb_user_arjun') do

user_id = FacebookWrapper.user_id('arjun')

expect(user_id).to eq '7901103'

end

end

end

spec/lib/facebook_wrapper_spec.rb

Even Better

Record API automatically

Replay responses without network

Verify responses

Additional Build Process

Runs outside normal test mode

Rechecks cassettes for diffs

Avoids versioning issues

gem 'puffing-billy'

Puffing-Billy

Built for in-browser requests

Allowed to record and reuse (like VCR)

Be brave, venture out

of ruby

I also like…

Chrome Dev Tools

Postman

HTTPie

Charles

Additional Readingmartinfowler.com/bliki/IntegrationContractTest.html

robots.thoughtbot.com/how-to-stub-external-services-in-tests

joblivious.wordpress.com/2009/02/20/handling-intermittence-how-to-

survive-test-driven-development

railscasts.com/episodes/291-testing-with-vcr

Bringing it all together

Testing services is crucial

If in doubt, stub it out

Determine the flexibility you want

Record responses to save time

Next Up

Eliminating Inconsistent Test Failures

with Austin Putman

Thank you!

me@nealke.mp

(I like emails)

@neal_kemp

(I tweet)