object-oriented bdd w/ cucumber by matt van horn

OBJECT ORIENTED BDD

with CUCUMBER

Thursday, October 3, 13

Who Am I?

Senior So(ware Engineer at New Relic

20 years of web applica9on development

12 years of TDD

5 years of BDD

github.com/maFvanhorn or @nycplayer


New Relic CI


New Relic CI

Github, TDDium, Jenkins

Feature branches, Pull Requests

Automa9c builds, Code reviews

Automated deploys, but some manual control


New Relic CI

We deploy 3x per day

Automated tes9ng is part of the process

However...


New Relic CI

We have a large, slow test suite

We have a large, legacy Rails app

We have a lack of up-‐to-‐date documenta9on

We o(en have communica9on issues


New Relic CI

We want to go from 3x/day to ‘at will’

We are dedica9ng 9me to improving our tests

Automated acceptance tests are key

(Faster unit tests are also important)


BehaviorDrivendevelopment


BehaviorDrivendevelopmentBDD is a second-‐genera9on, outside–in, pull-‐based, mul9ple-‐stakeholder, mul9ple-‐scale, high-‐automa9on, agile methodology. It describes a cycle of interac9ons with well-‐defined outputs, resul9ng in the delivery of working, tested so(ware that maFers.

-‐ Dan North


BehaviorDrivenDevelopment

“BDD describes TDD done well”

-‐ MaF Wynne


BehaviorDrivenDevelopment“Can you give me some examples (of using it)?”

vs.

“What are the requirements (for implemen9ng it)?”


Outside In

Start with a conversa9on

Determine the business value

Provide examples of use


Outside In User Interface

Browser

Views

Controllers

Models


Outside In User Interface

Browser

Views

Controllers

Models

Cucumber

RSpec


Outside InRed, Green, REFACTOR

Outer loop: Features, stories, scenarios

Inner loop: Unit tests, classes, methods

Cucumber


Red, Green, REFACTOR



Outside In Cucumber

RSpec


Outside In Cucumber

RSpecRed, Green, REFACTOR




BDD TOOLS

Cucumber, RSpec, FitNesse

Gherkin

Spinach, Turnip, Steak, Filet

Capybara, Wa9r, WebRAT

Selenium, Webkit, PhantomJS, Rack::Test


Cucumber Complaints

Don’t need English, code is fine

Doesn’t save developer 9me

BriFle tests, needing constant maintenance


You’reDoING ITWRONG


Cucumber Done right

Minimizes miscommunica9on

Hides implementa9on details

Provides robust regression tests

Communicates inten9ons


Cucumber Done right

Cucumber allows us to inform, in plain English, the intended behavior of applica9ons we build to future developers, rather than forcing them to spelunk through code to figure it out.

-‐ Ma, Polito


Object ORientedCucumber


Object ORientedCucumber

Keep data and behavior together

Hide implementa9on details

Send messages to accomplish tasks


Page Object

URLs

UI Elements

Page Sections

DomainAction

Methods

BrowserDriver


Page Object

Provides a model for a web UI

Hides details of dealing with browser

Keeps UI details in one place

Enables expressive test code


Site Prism

Open source Ruby gem

Provides simple DSL for page Objects

Exposes Capybara nodes


Technique

Plain English, not code (or pseudo-‐code)

Domain concepts, not implementa9on details

Focus on the value, not the incidentals


Stories & Scenarios Impera9ve

Scenario: Typical Meetup

Given I am on the estimate page When I fill in "Guest count" with "10" And I fill in "Slice count" with "2" And I press "Get Estimate" Then I should see "You will need to order 3 pizzas"


“English -‐ we hateses it”

Scenario: Typical Meetup

Given I am on “/estimates/new” And I fill in "input#guests" with "10" And I fill in "input#slices" with "2" And I press "input[type=’submit’]" Then I should see "You will need to order 3 pizzas"

Stories & Scenarios


Stories & Scenarios

Declara9ve

Scenario: Typical Meetup (Guests eat 2 slices each)

Given There are 10 guests expected When I ask how much to order Then I will know I need to buy 3 pizzas


ExamplesFeature: Estimating Pizza Requirements In order to avoid wasting either pizza or money As an organizer I want to know how many pizzas I need to order

Background: Given there are 10 guests expected

Scenario: Typical meetup (Guests eat 2 slices) Given the guests are hungry When I ask how much to order Then I will know I need to buy 3 pizzas

Scenario: Late-night meetup (Guests eat 3 slices) Given the guests are starving When I ask how much to order Then I will know I need to buy 4 pizzas

Scenario: After-lunch meetup (Guests eat 1 slice) Given the guests are full When I ask how much to order Then I will know I need to buy 2 pizzas


Step Definitions

Use methods that relate to the domain

Avoid nes9ng steps

Mostly black box

Some white box can be very useful


ExamplesGiven(/^there are (\d+) guests expected$/) do |guest_count| Site.new_estimate_page.guests_expected = guest_countend

Given(/^the guests are (full|hungry|starving)$/) do |hunger_level| Site.new_estimate_page.hunger_level = hunger_levelend

When 'I ask how much to order' do Site.new_estimate_page.request_estimateend

Then(/^I will know I need to buy (\d+ pizzas)$/) do |pie_count| expect(Site.new_estimate_page).to have_text("#{pie_count}")end


Examples# Utility class to provide easy access to page objects.class Site def self.current_page @current_page end

def self.method_missing(meth_name, *args) klass = meth_name.to_s.classify @current_page = klass.constantize.new endend


Examplesclass NewEstimatePage < SitePrism::Page URL = Rails.application.routes.url_helpers.root_path

set_url URL set_url_matcher %r(#{URL})

element :guests_field, "input[name='estimate[guest_count]']" element :slices_field, "input[name='estimate[slice_count]']" element :submit_btn, "input[name='commit']"

# ... instance methods elided ...

end


Examplesclass NewEstimatePage < SitePrism::Page # ... DSL elided ...

def guests_expected=(guest_count) load unless displayed? guests_field.set guest_count end

def hunger_level=(hunger) load unless displayed? slices_per_person = case hunger when 'full' then 1 when 'hungry' then 2 when 'starving' then 3 end slices_field.set slices_per_person end

def request_estimate load unless displayed? submit_btn.click endend


DEMO


Changes


Product Manager:

“We should es9mate beer as well”

“It should work the same way as pizza”


Application Changes:

Change es9mate model

Change form view

Change es9mate view

Change es9mate view helper


Cucumber Changes:

Change scenarios

Add steps for new scenario changes

Add elements to page model

Add methods to page model to use elements


Examples Scenario: Typical meetup Given the guests are hungry And the guests love beer When I ask how much to order Then I will know I need to buy 3 pizza pies And I will know I need to buy 1 case and 1 six-pack of beer

Scenario: Late-night meetup Given the guests are starving And the guests like beer When I ask how much to order Then I will know I need to buy 4 pizza pies And I will know I need to buy 1 case of beer

Scenario: After-lunch meetup Given the guests are full And the guests are underage When I ask how much to order Then I will know I need to buy 2 pizza pies And I will know I don't need to buy beer


ExamplesGiven(/^the guests (like|love) beer$/) do |thirst| Site.new_estimate_page.thirst_level = thirstend

Given(/^the guests are underage$/) do Site.new_estimate_page.thirst_level = 'none'end

Then(/^I will know I need to buy ((?:\d+ cases?)?(?: and )?(?:\d+ six\-packs?)? of beer)$/) do |content| expect(Site.new_estimate_page).to have_text(content)end

Then(/^I will know I don't need to buy beer$/) do expect(Site.new_estimate_page).to have_text("no beer")end


Examplesclass NewEstimatePage < SitePrism::Page

# ... URL matchers elided ...

element :guests_field, "input[name='estimate[guest_count]']" element :slices_field, "input[name='estimate[slice_count]']" element :beers_field, "input[name='estimate[beer_count]']" element :submit_btn, "input[name='commit']"

# ... other methods elided ...

def thirst_level=(thirst) load unless displayed? beer_count = case thirst when 'none' then 0 when 'like' then 2 when 'love' then 3 end beers_field.set beer_count endend


Examples


Refactor


ExamplesGiven(/^there are (\d+) guests expected$/) do |guest_count| Site.new_estimate_page.guests_expected = guest_countend

Given(/^the guests are (full|hungry|starving)$/) do |hunger_level| Site.new_estimate_page.hunger_level = hunger_levelend

When 'I ask how much to order' do Site.new_estimate_page.request_estimateend

Then(/^I will know I need to buy (\d+ pizza pies)$/) do |pie_count| expect(Site.new_estimate_page).to have_text("#{pie_count}")end


HELPER ModulesHelpers are glue between inten9on and implementa9on

Swapping out helpers can adapt your suite to different plajorms or devices

Page Objects are for page based UIs, but the principles can be applied to other domains


Examplesmodule WebHelper def guests_expected count Site.new_estimate_page.guests_expected = count end

def general_hunger_level hunger Site.new_estimate_page.hunger_level = hunger end

def general_thirst_level thirst Site.new_estimate_page.thirst_level = thirst end

def submit_request_for_estimate Site.new_estimate_page.request_estimate end

def verify_pizzas_needed num_pies expect(Site.new_estimate_page).to have_text("#{num_pies} pizza pies") end

def verify_beer_needed beer_text expect(Site.new_estimate_page).to have_text(beer_text) endendWorld(WebHelper)


Product Manager:

“It’s too easy to make typos.”

“Last week Ted ordered 33 beers per person.”

“The carpet is s9ll not completely clean.”


Application Changes:

Change form view to use different widgets


Cucumber Changes:

Update page object to use new elements


Examples element :slices_field, "input[name='estimate[slice_count]']" element :beers_field, "input[name='estimate[beer_count]']"

def hunger_level=(hunger) load unless displayed? slices_per_person = case hunger when 'full' then 1 when 'hungry' then 2 when 'starving' then 3 end slices_field.set slices_per_person end

def thirst_level=(thirst) load unless displayed? beer_count = case thirst when 'none' then 0 when 'like' then 2 when 'love' then 3 end beers_field.set beer_count end


Examplesclass NewEstimatePage < SitePrism::Page

element :hunger_select, "select[name='estimate[slice_count]']" element :thirst_select, "select[name='estimate[beer_count]']"

def hunger_level=(hunger) load unless displayed? hunger_select.select hunger end

def thirst_level=(thirst) load unless displayed? thirst_select.select case thirst when 'like' then 'thirsty' when 'love' then 'extremely thirsty' else 'none' end endend


Examples


MORE Changes


Product Manager:

“We’re adding a registra9on feature.”

“Entering the number of guests is redundant.”

“We’ll count the guests in the database.”


Application Changes:Create Guest model, with db migra9on

Add guest list view with add guest form

Add guests controller

Change routes to add guest routes

Change es9mate form view

Change es9mate controller


Cucumber Changes:

Change the step that sets up the number of guests.


Examples

Given /^there are (\d+) guests expected$/ do |guest_count| guests_expected guest_countend


Examples

Given /^there are (\d+) guests expected$/ do |guest_count| guest_count.times{ Fabricate(:guest) }end


Alternative

Change the implementa9on of the method the step calls.


Alternative

def guests_expected guest_count Site.new_estimate_page.guests_expected = count end


Alternative

def guests_expected guest_count guest_count.times{ Fabricate(:guest) } end


Alternative

module DatabaseHelper def guests_expected guest_count guest_count.times{ Fabricate(:guest) } endend


Alternative# support/helpers/database_helper.rb

module DatabaseHelper def guests_expected guest_count guest_count.times{ Fabricate(:guest) } endend

# support/helpers/helper_setup.rb

require_relative 'web_helper'require_relative 'database_helper'

World(WebHelper)World(DatabaseHelper)


Examples


platform changes


Examplesmodule PersonalAssistantHelper def general_hunger_level hunger PersonalAssistant.tell "Guests will be #{hunger}" end

def general_thirst_level thirst PersonalAssistant.tell "Guests will #{thirst} beer" unless thirst == 'none' end

def submit_request_for_estimate PersonalAssistant.ask "How much do I need?" end

def verify_pizzas_needed num_pies expect(PersonalAssistant.guess_pizza).to eq(num_pies) end

def verify_beer_needed beer_text expect(PersonalAssistant.guess_beer).to eq(beer_text) endend


SUMMARY

Keep implementa9on details in one place

Use objects to model the system

Use abstrac9on levels to scope changes

Express your intent throughout the code


QUESTIONS?


RESOURCESSource Code:

github.com/maFvanhorn/pizza_beergithub.com/natritmeyer/site_prism

Further Reading:mar9nfowler.com/bliki/PageObject.htmlblog.maFwynne.net/2012/11/20/tdd-‐vs-‐bdddannorth.net/2012/05/31/bdd-‐is-‐like-‐tdd-‐ifwww.elabs.se/blog/15-‐you-‐re-‐cuking-‐it-‐wronggojko.net/2013/09/30/wri9ng-‐as-‐a-‐user-‐does-‐not-‐make-‐it-‐a-‐user-‐story

Contact Me:web: maFvanhorn.comgithub: maFvanhorntwiFer: @nycplayeremail: mvanhorn@newrelic or [email protected]


object-oriented bdd w/ cucumber by matt van horn

Technology