Better Cucumber Features

Writing Better
Domain Oriented
Cucumber
Features
Amir Barylko

Better Cucumber Features

Who am I?
• Architect

• Developer

• Mentor

• Great cook

• The one who’s entertaining you for the next hour!

Behavior Driven Dev.

Text
Text

The rSpec Book

Amir Barylko - Better Cucumber Features

Why Projects Fail?
• Delivering late or over budget

• Delivering the wrong thing

• Unstable in production

• Costly to maintain


Improve Quality
• Unit Testing

• Integration Testing

• Acceptance Testing


BDD
• Implementing an application

• by describing its behavior

• from the perspective of the stakeholder


Outside In Approach

BDD TDD


Test First
• Write a test before any line of code

• Write minimum amount of code to make
the test pass

• Refactor code to eliminate “smells”


Gherkin DSL
• Business readable DSL

• Flush out requirements

• Documentation

• Automated testing

• Used by Cucumber,
SpecFlow, jBehave


Gherkin Keywords
• Feature • Then

• Scenario • And

• Given • But

• When


Features
Feature: Listing projects
As a user Free text!
I Want to see the list of projects
So I can choose one to see the details

Scenario: List all projects
(steps here to implement scenario)

Scenario: No projects are available
(steps here to implement scenario)


Scenario
Scenario: List all projects
Given I'm logged in Step 1

And I have some projects stored Step 2

When I browse the projects Step 3

Then I should see all of them listed Step 4


Running Features
• Parse the feature

• Parse the scenario

• For each scenario

• Find a step implementation

• Execute the code


Matching Step
• Matching regular expression
Given I have some projects stored Feature File

Given /^I have some projects stored$/
Step Def File


Step
Given /^I have some projects stored$/ do
projects = 10.times { random_valid_project }
fake_response = create_response(projects)
FakeWeb.register_uri(....)
end
Plain
Ruby!


What we want?
• Readability

• Ubiquitous Language

• Consistent use of terminology

• Express natural business intent

• Avoid technical aspects


Imperative style
Scenario: Redirect user to originally requested page
Given a User "dave" exists with password "secret"
And I am not logged in
When I navigate to the home page
Then I am redirected to the login form
When I fill in "Username" with "dave"
And I fill in "Password" with "secret"
And I press "Login"


What’s the problem?
• Who needs the passwords?

• Tightly coupled to page implementation

• Lacks domain language

• Brittle tests

• Does not tell a story (boring)


Declarative style
Scenario: Redirect user to originally requested page

Given I am an authenticated user

When I attempt to view restricted content

Then I am presented with a login form

When I authenticated with valid credentials

Then I should be shown the restricted content


Declarative vs Imperative
• Imperative is associated to “how” to do it

• Declarative is associated to “what” we
want

• Where’s the boundary?


Too abstract?
Scenario: The whole system
Given the system exists
When I use it
Then it should work, perfectly


Background steps
• Steps may have some degree of repetition

• Because they start with the same “state”

• So they share the first X steps


Similar scenarios
Scenario: Change Password
Given I am logged in
And I choose to change my password
When I enter a new password
Then my password should be changed

Scenario: Change Password with same credentials
When I enter the same password
Then I should see an error message explaining the problem


Create Background
Background: I want to change my password

Scenario: Change Password
When I enter a new password
Then my password should be changed

Scenario: Change Password with same credentials
When I enter the same password
Then I should see an error message explaining the problem


Using Tables
• Sometimes data is hard to put in a step

• with multiple entries

Scenario: Listing movies
Given the movie “Blazing saddles” released “7 Feb 1974”
And the movie “Young Frankenstein” released “15 Dec 1974”
And the movie “The Producers” released “10 Nov 1968”


Why the detail though?
• Do you really need the list?

Given I have some movies stored
When I browse the list
Then I should see the complete collection


Leaky Scenarios
• Each scenario leaves the system in a
particular state

• The state has to be cleaned up for the next
scenario

• Otherwise it will “leak” into it

• One scenario should not depend on another


Generating data
• Use a framework to generate valid data

• FactoryGirl is a very good option

• FactoryGirl.create(:customer)

• FactoryGirl.create(:invalid_bank_accout)

• Faker will help you to generate fake data


Transforms
• Steps can have arguments

• Though regular expression they don’t always
show intent

• And also we may need to “reuse” them


Steps with arguments
Given /^I search for a movie “([^"]*)”$/ do |name|
.... # some code here
end

Given /^I have a movie called “([^"]*)”$/ do |name|
end


Capture the argument
Given /^I search for a movie “(#{MOVIE_NAME})”$/ do |name|
end

MOVIE_NAME = Transform /^([^"]+)$/ do | movie_name |
movie_name.downcase
end


Helpers
• Helpers are a great tool to encapsulate
common functionality

• Or to help describe better our intention

• and to avoid looking at ugly code


Current Instance
• The World is created for each scenario

• Instance variables have to be set

• Instead we can use a helper method

• to store/create the resource


Helper Class
module ProjectHelper

def current_project(project = nil)
@current_project ||= project
end

def project_list_page
@project_list_page ||= ProjectListPage.new
end

end

World(ProjectHelper)


Custom matchers
RSpec::Matchers.define :match_stored_projects do
match do |actual|
actual == Project.all.map { ... }
end

failure_message_for_should do |actual|
"The projects in the page should match...n" +
"The page contains #{actual}' n" +
"But the storage contains #{@expected}"
end

end


Page Objects
• The steps rely on the HTML implementation

• Searching for elements can be repetitive

• or ugly

• and not always show intention


What can we do?
Then /^I should see the complete list of projects$/ do
actual = all(:css, "#projects tbody tr")
• .map { |tr| tr.all("td").map(&:text) }
.map { |cells| ... }
expected = Project.all.map { |p| ... }
actual.should == expected
end


Abstraction!
class ProjectListPage
include PageObject
•
def projects
all(:css, "#projects tr").
drop(1). #drop the header
map { |r| r.all(:css, 'td').map(&:text) }.
map { |r| Project.new(...) }
end
end


Nicer steps
projects_page.list.should == stored_projects
•
end

Page Object Helper


With a custom matcher
projects_page.should list_stored_projects
•
end

Custom
Matcher


Next steps
• Focus your scenarios on “what” not “how”

• Read about scenario outlines

• Follow “the Cucumber book” practices

• Learn more about page objects pattern

• Start with a simple project


Resources
• Email: amir@barylko.com,

• Twitter: @abarylko

• Blog: http://orthocoders.com

• Website: http://maventhought.com


Resources II

Better Cucumber Features

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