A LAZY Developer's
Guide to BDD
(with )
~ Ng Tze Yang (aka TY)

2 weeks ago, i changed it to:
Everyone gets a little
of 's ♥
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A LAZY Developer's
Guide to BDD
(with )
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WTF is “LAZY” ??
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LAZY= !(TATFT)
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WTF is “TATFT” ??
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Why Not TATFT ??
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Why Not TATFT ??
* What is most important for a
software ??
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Why Not TATFT ??
* What is most important for a
software ??
=> Business Value
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Why Not TATFT ??
* What is most important for a
software ??
=> Business Value
* How do we quantify BV ??
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Why Not TATFT ??
* What is most important for a
software ??
=> Business Value
* How do we quantify BV ??
=> Behaviours
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BDD
~ Behaviour Driven Development ~
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BDD
~ Behaviour Driven Development ~
“BDD facilitates agile development,
which is an approach to develop functional
software, within reasonable timeline, making
everyone happy, without killing anyone, or
burning down any bank.”
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BDD's Core Principles
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BDD's Core Principles
* It's all behaviour
“ The business & technology people
should be speaking the same words
when referring to the same idea,
there should not be any translator.”
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BDD's Core Principles
* It's all behaviour
Behaviour: the addition of N values
should yield the summation of them
Example: the addition of 2 + 4 +1
should yield 8
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BDD's Core Principles
* It's all behaviour
* Deliver stakeholder value
“ Whatever u are doing, it should be
delivering business value, or increasing
ur ability to deliver value, if the activity
doesn't acheive this, stop doing it”
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BDD's Core Principles
* It's all behaviour
* Deliver stakeholder value
“ Unit testing is important, as it makes
refactoring & regression testing easier, which
eases maintenace and enhance ur ability to
deliver newer features faster”
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BDD's Core Principles
* It's all behaviour
* Deliver stakeholder value
* Enough is enough
“ Do not overengineer, do not overdo
upfront planning, analysis and design.
Do just enough to get things started in the
right direction”
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BDD's Core Principles
* It's all behaviour
* Deliver stakeholder value
* Enough is enough
“ When i wanna go to sentosa from my AMK
home, i just goto gothere.sg to do a quick
check, and that's good enough, i don't need
to get down to switching lanes on CTE,
blah blah. ” 21

Cucumber ? Nice to Eat ?!
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Cucumber ? Nice to Eat ?!
* a tool for functional testing
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Cucumber ? Nice to Eat ?!
* a tool for functional testing
* by Aslak HellesØy, & many other
nice people
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Cucumber ? Nice to Eat ?!
* a tool for functional testing
* by Aslak HellesØy, & many other
nice people
* allows non-technies to express
app's functions in plain text
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Cucumber ? Nice to Eat ?!
* a tool for functional testing
* by Aslak HellesØy, & many other
nice people
* allows non-technies to express
app's functions in plain text
* plain text serves as documentation
& executable examples
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Hmm .. Plain Text ?!
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A Prettier Plain Text
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The Title
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The Narrative
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Guideline for the Narrative
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Guideline for the Narrative
* identify the stakeholder
“ Eg. The system administrator”
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Guideline for the Narrative
* identify the stakeholder
* describe the feature he wants
“ Eg. Trashing of all invalid purchase
orders in the system”
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Guideline for the Narrative
* identify the stakeholder
* describe the feature he wants
* the reason for wanting it
“ Eg. Prevent data corruption”
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The Acceptance Criterion
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The Scenario's Title
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The Scenario's Steps
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Given | When | Then
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Given | When | Then
* GIVEN ... setting up system to a
known state
“ Eg 1. Database setup ...
Given the following users already exists”
“ Eg 2. Visiting a Url ...
Given I am on users management page”
“ Eg 3. Ensure User's Login ...
Given I already login as “HappyMan””
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Given | When | Then
* GIVEN ... setting up system to a
known state
* WHEN ... exercising an event
“ Eg. Pressing Button ...
When I press “Help Me””
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Given | When | Then
* GIVEN ... setting up system to a
known state
* WHEN ... exercising an event
* THEN ... verifying an outcome
“ Eg. Seeing a message ...
Then I should see “Login Successful””
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Save & Execute It !!
* Save at:
<PROJECT_ROOT>
`~ features/
`- sign_up.feature
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Save & Execute It !!
* Save at:
<PROJECT_ROOT>
`~ features/
`- sign_up.feature
* Run with:
#$ cucumber features
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P1
P2
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Step Definitions
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Save & Execute It !!
* Save as:
<PROJECT_ROOT>
`~ features/
`- steps.rb
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Save & Execute It !!
* Save as:
<PROJECT_ROOT>
`~ features/
`- steps.rb
* Run with:
#$ cucumber features
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The Functional Test Model
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The Generic Model
Cucumber
* cucumber exec
* features/*.feature
* features/*.rb
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The Generic Model
Cucumber
* cucumber exec Target App
* features/*.feature
* features/*.rb
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The Generic Model
Cucumber
* cucumber exec Target App
* features/*.feature
* features/*.rb
Driver
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The Generic Webapp Model
Cucumber
* cucumber exec
* features/*.feature
* features/*.rb
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The Generic Webapp Model
Cucumber Webapp
* cucumber exec * web server
* features/*.feature * deployed app
* features/*.rb * web browser
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The Generic Webapp Model
Cucumber Webapp
* cucumber exec * web server
* features/*.feature * deployed files
* features/*.rb * web browser
Driver
* selenium (server+client)
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FAST FOWARD
(Completed: Step Definitions)
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Before
After
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Before
After
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Before
After
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Before
After
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Before
After
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A New *.rb File
<PROJECT_ROOT>
`~ features/
`- selenium.rb
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OK, Let's Run It !!
#$ cucumber features
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Run Selenium Server
#$ selenium
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Run Selenium Server
#$ selenium
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Let's Try Again
#$ cucumber features
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The Missing Part ??
~ Our Application ~
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FAST FOWARD AGAIN
(Completed: Application)
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Let's Run the Webapp
#$ ruby app.rb
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Let's Run the Webapp
#$ ruby app.rb
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Let's Try Once Again
#$ cucumber features
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Let's Try Once Again
#$ cucumber features
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Revision Time
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Summing Up
1) Capturing user's requirements
in a feature file
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Feature's Title
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Feature's Narrative
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Feature's Narrative
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Feature's Narrative
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Feature's Narrative
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Feature's Acceptance Criterion
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Feature's Acceptance Criterion
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Feature's Acceptance Criterion
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Summing Up
1) Capturing user's requirements
in a feature file
2) Complete the missing step
defintions
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Step Definitions
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Summing Up
1) Capturing user's requirements
in a feature file
2) Complete the missing step
defintions
3) Implement the application
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Useful Links
* Cucumber's Wiki
http://wiki.github.com/aslakhellesoy/cucumber
* Cucumber's Homepage
http://cukes.info/
* BDD @ Wikipedia
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Recommended Video
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THE END
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