This talk is about how you can use specification by example to write bottom-up TDD. I use TDD as if you meant it as the extreme classicist TDD aproach for showing how you can grow your systems bottom-up. See here the flipchart pictures from during the presentation: http://t.co/icWxBzxQDr http://t.co/zI66uvYbLW http://t.co/Yy1JCJ2AZp See here the codebase: https://github.com/adi-bolb/FoldingTheSoftwareDesignSpace/commits/01-bottom-up-specification-by-example?page=2 Picture from during the session: https://www.flickr.com/photos/sebastian_bergmann/14684033197/in/set-72157646302093521

1. Folding the Design
Space Case Study:
TDD with
Specification by
Example
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2. Me
Adi Bolboacă
Programmer
Organizational & Technical
Trainer & Coach www.mozaicworks.com

3. TDD
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4. TDD As if you Meant It
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1) Write exactly one failing test
2) Make the test pass by writing implementation code in
the test method
3) Create a new implementation method by:
a) Extracting implementation code to a new method in
the test class
b) Moving implementation code into an existing
implementation method from the test class
4) Create implementation classes to provide a destination
for extracting a method in the test class
5) When necessary move implementation methods into
implementation classes
6) Refactor as required

5. Classicist TDD
Prefer writing state tests
Usually start bottom-up
Do not use test doubles unless necessary
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6. 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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7. 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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8. Problem: Conway's Game of Life
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Having an infinite 2D orthogonal universe
Being given an initial generation called a seed
The following rules are applied simultaneously
A live cell having less than 2 live neighbors
dies
A live cell having 2 or 3 live neighbors lives
A live cell having more than 3 neighbors dies
A dead cell having 3 neighbors becomes alive

9. 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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10. Incremental design
I want to introduce one notion at a time.
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11. The visible notions from Conway's
Game of Life
Cell
Board
Universe
Life state
Generation
Set of rules
Neighbourhood
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12. Start with Incremental design
Simplify the problem
Introduce only one notion at a time
Find the main functionality: Tick()
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13. Question
What would the simplest first step be?
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14. Option: Slider Gun
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15. www.mozaicworks.com

16. Requirements
From real life examples
“Specification by Example”
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17. 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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18. Thank you!
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19. 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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20. Enterprise Agile Architect Role
Contact me
Unit testing workshop
Remote pair-programming
TDD workshop
Refactoring workshop
Legacy code workshop
Legacy code retreat
Code retreat
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21. Enterprise Agile Architect Role
Extend your mentoring & training
capacity
Accelerate learning through
communities of practice
Grow your functional leaders and top
talents
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adrian.bolboaca@mozaicworks.com
@adibolb