folding the design space @socrates germany 9 august 2014
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Folding the Design Space Case Study: TDD with Specification by Example
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Me
Adi BolboacProgrammerOrganizational & TechnicalTrainer & Coach
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TDD
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TDD As if you Meant It
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Write exactly one failing test
Make the test pass by writing implementation code in the test method
Create a new implementation method by: Extracting implementation code to a new method in the test class
Moving implementation code into an existing implementation method from the test class
Create implementation classes to provide a destination for extracting a method in the test class
When necessary move implementation methods into implementation classes
Refactor as required
Classicist TDD
Prefer writing state tests
Usually start bottom-up
Do not use test doubles unless necessary
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Mockist TDD
Prefer writing collaboration tests
Usually start top-down
Always test in isolation
Use only one mock at a time for a test
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Specification by Example
[...]Defining requirements and business-oriented functional tests for software products based on capturing and illustrating requirements using realistic examples instead of abstract statements.
[http://en.wikipedia.org/wiki/Specification_by_example]
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Problem: Conway's Game of Life
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Having an infinite 2D orthogonal universeBeing given an initial generation called a seed
The following rules are applied simultaneously
A live cell having less than 2 live neighbors diesA live cell having 2 or 3 live neighbors lives A live cell having more than 3 neighbors diesA dead cell having 3 neighbors becomes alive
Purposes of the session
I care about specifications and I don't care about representation
Have the cleanest design possible with highly cohesive structures
Use real life examples as specifications
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Incremental design
I want to introduce one notion at a time.
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The visible notions from Conway's Game of Life
CellBoard
Universe
Life state
Generation
Set of rules
Neighbourhood
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Start with Incremental design
Simplify the problem
Introduce only one notion at a time
Find the main functionality: Tick()
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Question
What would the simplest first step be?
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Option: Slider Gun
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Requirements
From real life examples
Specification by Example
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Step 1
empty universe => empty universe
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Step 1
empty universe => empty universe
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Step 1
empty universe => empty universe
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Step 1
empty universe => empty universe
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Conclusions
When the solution is less known TDD as if you meant it is useful
Bottom-up TDD is useful to grow a system
You need to refactor more with TDD bottom-up
The design increments are smaller bottom-up
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Thank you!
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References
http://4.bp.blogspot.com/_9kQQgQD35rY/SaV5p8YBGhI/AAAAAAAAAkg/HOvlhIo7yGI/s1600-h/06_Red_Green_Refactor.JPG
http://upload.wikimedia.org/wikipedia/commons/e/e5/Gospers_glider_gun.gif
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Enterprise Agile Architect Role
Contact meUnit testing workshopRemote pair-programmingTDD workshopRefactoring workshopLegacy code workshopLegacy code retreatCode retreat
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Enterprise Agile Architect Role
Extend your mentoring & training capacityAccelerate learning through communities of practiceGrow your functional leaders and top talents
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@adibolb