What is BDD and why should I care?

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What is BDD ...and why should I care? @mattwynne BCS, Edinburgh 3rd October 2012

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Living documentation BDD Kickstart.com mattwynne.net Coaching / blogging training Collaborating

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BDD: Dual Audience Stakeholders, Customers, Users Programmers, Testers

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Problem domain Solution domain

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"Behaviour-Driven Development (BDD) builds upon Test-Driven Development (TDD) by formalising the good habits of the best TDD practitioners." -- The Cucumber Book, 2011

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The best TDD practitioners... • Work from the outside-in • Use examples to clarify their requirements • Develop and use a ubiquitous language

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UBIQUITOUS LANGUAGE

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DDD + NLP

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Language matters DDD + NLP

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OUTSIDE IN

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Outside-in

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Why?

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Why? Why? Why? Why? Why?

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Organisation Goal

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Product Features / Epics

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User / Stakeholder Stories

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VISA subscriptions In order to increase subscriptions visitors should be able to subscribe online with a VISA card User / Stakeholder Story

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VISA subscriptions In order to increase subscriptions visitors should be able to subscribe online with a VISA card User / Stakeholder Story

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VISA subscriptions In order to increase subscriptions visitors should be able to subscribe online with a VISA card User / Stakeholder Story

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VISA subscriptions In order to increase subscriptions visitors should be able to subscribe online with a VISA card User / Stakeholder Story

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VISA subscriptions In order to increase subscriptions visitors should be able to subscribe online with a VISA card Acceptance Criteria

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Acceptance Criteria •Must support VISA •Does not need to support MasterCard, Switch •... •Customers should be prevented from entering invalid credit card details • ... Credit Card Processing Acceptance criteria:

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Acceptance Criteria

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Are we ready yet?

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Really? So tell me... "Customers should be prevented from entering invalid credit card details"

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Really? So tell me... "Customers should be prevented from entering invalid credit card details" • What exactly makes someone's credit card details invalid?

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Really? So tell me... "Customers should be prevented from entering invalid credit card details" • What exactly makes someone's credit card details invalid? • Can they use spaces?

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Really? So tell me... "Customers should be prevented from entering invalid credit card details" • What exactly makes someone's credit card details invalid? • Can they use spaces? • Should we checksum the digits? • How do we feed back that the details are invalid?

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EXAMPLES

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Acceptance Criteria

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Scenarios

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"Customers should be prevented from entering invalid credit card details" 1. Customer enters a credit card number that contains only 15 digits 2. Customer tries to submit the form 3. form is re-displayed with an error message advising Customer that the correct number of digits is 16 For example, imagine this scenario:

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Common understanding of Done

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User Story Acceptance Criteria Scenarios

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Scenarios

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AUTOMATION

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Behaviour = Context + Action + Outcome

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Behaviour = Context + Action + Outcome Given

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Behaviour = Context + Action + Outcome Given When

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Behaviour = Context + Action + Outcome Given When Then

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Scenario: Tickle a happy person Given I am in a good mood When you tickle me Then I will giggle

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Scenario: Tickle a happy person Given I am in a good mood When you tickle me Then I will giggle

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Scenario: Tickle a grumpy person Given I am in a bad mood When you tickle me Then I will giggle

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Scenario: Tickle a grumpy person Given I am in a bad mood When you tickle me Then I will giggle expected: "tee hee hee", got: "bugger off"

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Scenario: Tickle a grumpy person Given I am in a bad mood When you tickle me Then I will get cross

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Scenario: Attack a happy person Given I am in a good mood When you kick me in the shins Then I will get cross

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Scenario: Attack a happy person Given I am in a good mood When you kick me in the shins Then I will get cross

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Behaviour = Context + Action + Outcome

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Behaviour = Context + Action + Outcome Given

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Behaviour = Context + Action + Outcome Given When

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Behaviour = Context + Action + Outcome Given When Then

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System = ∑(Behaviour)

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http://cukes.info/

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Javascript

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Demo

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Gherkin (language)

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# language: en Feature: Division In order to avoid silly mistakes Cashiers must be able to calculate a fraction Scenario: Regular numbers Given I have entered 3 into the calculator And I have entered 2 into the calculator When I press divide Then the result should be 1.5 on the screen

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# language: ja ϑΟʔνϟ: আࢉ όΧͳؒҧ͍Λආ͚ΔͨΊʹ ༗ཧ਺΋ܭࢉͰ͖Δ͜ͱ γφϦΦ: ;ͭ͏ͷ਺஋ લఏ 3 Λೖྗ ͔ͭ 2 Λೖྗ ΋͠ divide Λԡͨ͠ ͳΒ͹ 1.5 Λදࣔ

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български català Cymraeg Česky dansk Deutsch English Australian LOLCAT Texan español eesti keel ೔ຊޠ 한국어 lietuvių kalba latviešu Nederlands norsk polski português română suomi français hrvatski magyar Bahasa Indonesia italiano русский Svenska Slovensky Узбекча Tiếng Việt 简ମதจ ൟᱪதจ תירבע !"#$%&ا

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OH HAI: STUFFING MISHUN: CUCUMBR I CAN HAZ IN TEH BEGINNIN "3" CUCUMBRZ WEN I EAT "2" CUCUMBRZ DEN I HAZ "2" CUCUMBERZ IN MAH BELLY AN IN TEH END "1" CUCUMBRZ KTHXBAI!

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Gherkin Fundamentals Feature: Feature name Description of feature goes here Scenario: Scenario name Description of scenario goes here Given a certain context When something happens Then an outcome And something else But not this though Scenario: Another scenario name Description of another scenario goes here ...

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FORGET THE TOOLS

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"Let's make toast the American way: You burn it, and I'll scrape it" - W. E. Demming

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Plan

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Plan Develop

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Plan Develop Misery

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Plan Develop Testing

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Plan Develop Testing

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Plan Develop Test

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So... why should I care?

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If you're a developer

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If you're a developer • BDD will help you to focus

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If you're a developer • BDD will help you to focus • BDD will give you conﬁdence to refactor

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If you're a developer • BDD will help you to focus • BDD will give you conﬁdence to refactor • BDD will help you to understand the business-facing people on your team better

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If you're a product owner or business analyst

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If you're a product owner or business analyst • BDD will give you a greater insight into the complexity of what you're asking for

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If you're a product owner or business analyst • BDD will give you a greater insight into the complexity of what you're asking for • BDD will give you transparency about what the team are doing in each iteration

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If you're a tester

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If you're a tester • BDD will mean you can ﬁnd bugs before they've even been written

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If you're a tester • BDD will mean you can ﬁnd bugs before they've even been written • BDD will free you to do interesting, creative, exploratory testing

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If you're a project manager

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If you're a project manager • BDD will help your team achieve a steadier, more predictable, and ultimately faster pace

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Thanks • matt@mattwynne.net • @mattwynne • http://blog.mattwynne.net