why bdd is our bff

Matt DaubertMeYou Health@mdaubs83

TDD is about code design

“It’s harder to read code than to write it.”

- Joel Spolsky

“Agile processes harness change”

- 2nd Principle, Agile Manifesto

“No matter how slow you are writing clean code, you will always be slower if you

make a mess.”- Uncle Bob Martin

TDD does not address...

Which test do I need to write next?

Starting point.

How do I know when I’ve written the last test?

Definition of done.

How does this new code add value for the user?

Am I writing the right code?

BDD

TDD

Unit test

Code to pass test

Refactor

Scenario

“If you can’t explain it simply, you don’t understand it well

enough.”- Albert Einstein

Developingacceptancetests

Implementingacceptance

tests

Successful products provide value to users.

Users derive value by interacting with products.

Interactions are testable.

Two sides to every (user) story

Narrative- User/persona/role- Goal or value the user would like to achieve- The interaction the user should have with the product in order to achieve their goal and gain value

Acceptance Criteria- Multiple concrete examples describing how the feature works

Our goals, user goals

Scope

Specification

Key Examples

Acceptance Test

Living Documentation

Dom

ain Language

Shared U

nderstandingincreasing

Ain't Nobody Got Time For That

Refining User Stories

- Stories are refined through collaboration

- Stories may divide if they get complex

- Stories will often start with a small number of key examples and expand as shared understanding develops

- Refinement is complete when a story passes the "INVEST" test.

INVEST in User Stories

INVEST in User Stories

IndependentCan be scheduled and re-prioritized with minimal risk of being blocked.

INVEST in User Stories

IndependentNegotiableCan be changed or discarded if business, market, or technical needs require.

INVEST in User Stories

IndependentNegotiableValuableStories that don't add value for users will never see a return on investment.

INVEST in User Stories

IndependentNegotiableValuableEstimableA reasonable idea of effort required to complete is needed to pace the sprint.

INVEST in User Stories

IndependentNegotiableValuableEstimableSmallQuicker to implement, minimize risk, get feedback sooner.

INVEST in User Stories

IndependentNegotiableValuableEstimableSmallTestableA story isn't considered done until its acceptance tests pass.

What is an acceptance test?

● Executable version of a refined user story

● Written in domain language

● Scenarios validate story acceptance criteria

● Defines start and finish lines

● Documents value proposition

● Respects "Three Levels of Description"

Three Levels of Description

Business RuleWhat is the scenario demonstrating?

Scenario: Free delivery is offered to customers who order two or more books

Three Levels of Description

Business RuleWhat is the scenario demonstrating?

User WorkflowHow can a user exercise the functionality?

Given I put two books in my cart

When I checkout

Then I should be able to select free delivery

Three Levels of Description

Business RuleWhat is the scenario demonstrating?

User WorkflowHow can a user exercise the functionality?

Technical ActivityWhat are the technical steps required to exercise each workflow step?

step 'I checkout' do

click_on 'Checkout'

end

Protips(Lightning Round)

Disambiguate w/Concrete ExamplesScenario Outline: Users cannot sign in after the sixth failed sign in attempt over a one

day period

Given I have failed to sign in <yesterday> times yesterday

And I have failed to sign in <today> times today

Then I should be <result> to sign in

Examples:

| yesterday | today | result |

| 0 | 0 | able |

| 0 | 5 | able |

| 0 | 6 | unable |

| 5 | 0 | able |

| 5 | 5 | able |

| 5 | 6 | unable |

| 6 | 0 | able |

| 6 | 5 | able |

| 6 | 6 | unable |

Gherkin Protip: Hide Implementation

Scenario: Selected customers are notified of a flash sale

Given I am a store manager

When I create a flash sale for VIP customers that starts tomorrow

And it’s tomorrow

And Resque jobs are run

Then VIP customers receive a Flashmail

Gherkin Protip: Hide Implementation

Scenario: Selected customers are notified of a flash sale

Given I am a store manager

When I create a flash sale for VIP customers

Then VIP customers receive a Flashmail the day of the flash

Gherkin Protip: Don’t Write Scripts

As a party planner with BFFs

In order to have the best party ever

I want to invite as many BFFs as possible

Given there is a user named Alice

And there is a user named Bob who is BFFs with Alice

And there is a user named Charlie who is BFFs with Bob

When Alice invites Bob to a party

But Alice does not invite Charlie to the same party

Then Alice receives a message

"Do you also want to invite Charlie?"

Gherkin Protip: Don’t Write Scripts

As a party planner with BFFs

In order to have the best party ever

I want to invite as many BFFs as possible

Given I am planning a party

When I invite my BFF Bob

Then I am asked if I might want to invite his BFF Charlie

Gherkin Protip:

Be skeptical of "I should see" stepsIs the act of seeing the thing valuable to the user or is it an implementation detail?

YesThen I should see that the patron has overdue books

NoThen I should see the overdue book icon

Gherkin Protips:

Be skeptical of "And" and “But” keywordsAre these steps really one step?Are these steps not focused on the feature?Is this feature really two features?

Be skeptical of "and" and "or" in stepsIs this step really two steps?Is this scenario really two scenarios?

Gherkin Protips:

Don't test every caseAdd examples to disambiguate around edge cases

Never use generic steps to DRY testsDRY Ruby code behind the steps

Listen when your Gherkin fights youCan you explain the feature in simple terms?

Use ctags - Never Grep for Steps

● Open a .feature file

● Move cursor to a scenario step

● Press Ctrl+] to open the step definition

● Press Ctrl+t to go back to the .feature file

Step Definitions# Gherkin

When I sign up with "email@example.com" and "password"

# Cucumber step definition

When /^I sign up (?:with|as) "(.*)" and "(.*)"$/ do |email, pw|

# More Ruby code here

end

# Turnip step definition

step "I sign up with/as :email and :password" do |email, pw|

# More Ruby code here

end

Use Custom Placeholdersstep "there are :count monsters" do |count|

count.times { Monster.new(name) }

end

placeholder :count do

match /\d+/, &:to_i # { |count| count.to_i }

match /no/ { 0 }

end

(or use Step Argument Transforms in Cucumber)

Use Helper Methods

module MyAccountSteps

step 'I am modifying my AwesomeApp account' do

sign_in @user = create(:user)

select_from_user_drop_down 'My account'

end

end

Organize Your Suite

spec|- acceptance |- features |- encouragement.feature |- macros |- session_macros.rb

|- steps |- encouragement_steps.rb

Every product and team is different, optimize for yours.

Thanks!

Matt DaubertMeYou Health@mdaubs83

Learn from smart peoplehttp://alindeman.github.io/acceptance_testing

http://blog.carbonfive.com/2012/02/14/beginning-outside-in-rails-development-with-cucumber-and-rspec/

http://en.wikipedia.org/wiki/INVEST_(mnemonic)

http://specificationbyexample.com/

http://janetgregory.blogspot.com/2010/08/atdd-vs-bdd-vs-specification-by-example.html

http://www.drdobbs.com/tdd-is-about-design-not-testing/229218691