bdd - beyond: given, when and then
DESCRIPTION
Behaviour Driven Development (BDD) is an evolution of test-driven development that places explicit emphasis on language, communication and 'outside-in' development. Many people are familiar with the 'Given,When,Then' structure used in BDD specifications (or acceptance tests) but is that really where it ends? In this session Antony Marcano gives a short intro to BDD, explains 'outside-in' development. Using a metaphor from learning theory and HCI principles, he'll show you how to go beyond 'Given,When,Then' to a shared understanding of your customer's needs.TRANSCRIPT
Behaviour Driven DevelopmentBeyond “Given, When, Then”
Antony Marcano
The Telephone Game
http://www.brokenpicturetelephone.com/
What is BDD?
Beyond “Given, When, Then”
BDD Origins
‘The deeper I got into TDD, the more I felt that my own journey had been less of a wax-on, wax-off process of gradual mastery than a series of blind alleys. I remember thinking “If only someone had told me that!”… I decided it must be possible to present TDD in a way that gets straight to the good stuff and avoids all the pitfalls. My response is behaviour-driven development (BDD). Over time, BDD has grown to encompass the wider picture of agile analysis and automated acceptance testing.’-Dan North
BDD Origins - Shortened
“ Behaviour Driven Development (BDD) builds upon Test-Driven Development (TDD) by formalising the good habits of the best TDD practitioners. ” – The Cucumber Book, Aslak Hellesøy, Matt Wynne
Some ‘Good Habits’
Slice VerticallyWork from the outside-in
One example at a time
Slice Vertically
2009 8
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…but defers feedback (often, until it’s too late)
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Iteration n Iteration n+1 Iteration x
time
Vertical slicing
…results in earlier feedback
Work from the outside-in
Outside-in
One example at a time
One example at a time
Elaborate as anautomated scenario (aka acceptance test)
Implement story driving with unit tests Scenario should pass
When all Scenarios pass, story is done(almost)
For each Example illustrating the story
Have a conversation
One example at a time
Test should fail
Expressing Examples
Given, When, ThenAnd beyond
Given When Then
Given <some initial context>When <something happens>Then <some expectation>
Given When Then
Given <some initial context>[and some additional context]
When <something happens>[and something else happens]
Then <some expectation>[and some more expectations]
A Typical Illustration
Scenario: Login SuccessfullyGiven I am on the home-pageWhen I enter the username ‘antony’And I enter the password ‘p4$$w0rd’And I click ‘login’
Then I should be logged in
What’s wrong with this example?
A Better Illustration
Scenario: Login SuccessfullyWhen I login as ‘antony’ with the password ‘p4$$w0rd’Then I should be logged in
Why is it better?
Task Analysis
A little UX for our BDD
• Pitching it right…– Goals e.g. Withdraw Cash
• Tasks Identify to bank Request amount
– (inter)actionsInsert Card
Enter PinPress “Withdraw Cash”
Enter amountPress OK
} Just right
} Too low level
For example…
When I add, the number ‘2’ and the number ’3’
http://cukesalad.info
actions}
task
Some nice side-effects
Encourages description of UI interactions in one place
Makes it easier to execute scenariosvia different interfaces
Discussion
Questions?Ideas?
Feedback?
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