2010 07-20 tdd with activeresource

API-based client/server API-based client/server applications with TDD and applications with TDD and

ActiveResource ActiveResource

Wolfram ArnoldWolfram Arnoldwww.rubyfocus.bizwww.rubyfocus.biz

In collaboration with:In collaboration with:Kurt SnyderKurt Snyder

papercheck.compapercheck.commarakana.commarakana.com

Database-backedDatabase-backed

DB

Application

ActiveRecord

SQL

API-backedAPI-backed

ClientApplication

ActiveResource

ServerApplication

API

JSON

DB

SQL

Tradeoffs?Tradeoffs?

DB-backed

Fast

ActiveRecord well developed

Complex relationships possible

Limited scalability—tight coupling

API-backed

Extra network & server latency

Complex relationships more difficult

Scales well to different front-ends—loose coupling

ClientApplication

(Flash or JS)

Frontend ScalabilityFrontend Scalability

ClientApplication

ActiveResource

ServerApplication

API

JSON

DB

SQL

ClientApplication

(Mobile)

Rails ActiveResourceRails ActiveResource

Model objects that behaves ActiveRecord objects

Maps CRUD operations to RESTful API

No Associations

No Validations (added in Rails 3)

Rougher around the edges than ActiveRecord

From CRUD to RESTFrom CRUD to REST

class Person < ActiveResource::Basesite “http://server.example.com/people”format :json

end

Person.create(:name => “Joe”)

→ POST /people, {'name':'Joe'}

Person.find(4)

→ GET /people/4

Resourceful RoutesResourceful Routes

map.resources :people (in config/routes.rb)

people_path, people_url “named route methods”

GET /people → “index” action

POST /people → “create” action

new_person_path, new_person_url

GET /people/new → “new” action

edit_person_path, edit_person_url

GET /people/:id/edit → “edit” action with ID

person_path, person_url

GET /people/:id → “show” action with ID

PUT /people/:id → “update” action with ID

DELETE /people/:id → “destroy” action with ID

Hyperactive ResourceHyperactive Resource

http://github.com/taryneast/hyperactiveresource

Adds Associations

Supports nested routes

/people/5/addresses/3

But: Cannot mix nested and non-nested routes for the same resource

Adds Validations

Let's do some codingLet's do some coding

Demo

RESTful Person Server API with JSON

HyperactiveResource-based client

TDD anyone?TDD anyone?

DB

Application

ActiveRecord

SQL

RSpec model testswith fixtures, factories

Test Databasewith transaction support

TDD ActiveRecord StyleTDD ActiveRecord Style

it “should create the object” dolambda { Person.create(:first_name => “Joe”)}.should change(Person, :count).by(1)

end

it “should destroy the object” dop = Factory.create(:person)lambda { p.destroy}.should change(Person, :count).by(-1)

end

API-backedAPI-backed

ClientApplication

ActiveResource

ServerApplication

API

JSON

DB

SQL

RSpec model test

Test DatabaseonTest Serverinstance!

Mocks anyone?Mocks anyone?

FakeWeb gem: http://github.com/chrisk/fakeweb

FakeWeb.register_uri(:get,"http://server.example.com/people",:body => "Hello World!")

Body is the mock object.

It should simulate the server response.

Great solution if it's a 3rd party server.

Problems with Mocks?Problems with Mocks?

If the server code is under our control...

What happens if the server API changes but the mock doesn't?

What process keeps the simulated server responses and the actual API in sync?

Better ideas?

Beyond MocksBeyond Mocks

Remote Specs

Rely on remote server running (in test environment)

Mechanism to set up data

Mechanism to inspect data

Mechanism to clean up data

Distributed Ruby “DRb”Distributed Ruby “DRb”

ClientApplication

DRb Client

ServerApplication

DRb Server

DRb

RemoteMethodInvocation

foo(args)

foo(args)

Demo DRb

Gotcha'sGotcha's

ActiveResource::Base.include_root_in_json

after_initialize hook for starting DRb server

:id problem for Objects, via DRb

Need to run server in test mode

Ideas/Questions:

Front Object in DRb?

rake task to start/stop server—reliably find process?

DRb port inflation—better way?

SummarySummary

Server application with REST controller

Client application with ActiveResource

Use DRb to:

test objects

inquire “actual” data

TDD with ActiveResource

BizConfBizConf

Aug 4-6, 2010

Amelia Island, FL

Discount code: WOLF

for 43% off

http://bizconf.org?coupon=WOLF

Rails & Web App Professionals, Entrepreneurs, Consultants

Small group

Network with Who's Who

Organized by Obie Fernandez of Hashrocket

Highlight: David Allen