Ryan Gough
Software developer, C# by day, Erlang and JS by night.
Test Driven Development
Red
Green
Refactor!
Red
-
Write a failing test
-
See it fail in the way you expect
Green
-
Make the test pass
-
Do this in the simplest possible way
Refactor!
Make the code good
- Remove Duplication
- Reduce coupling (connascence)
- SOLID
- Clean Code
TDD as if you mean it
- Write one test at a time
- Write methods / functions to make the test pass within the test file
- Extract "production" classes only when confident a good structure is emerging
- "Listen to the tests"
Pairing Ping Pong
-
Person A writes a failing test
-
Person B makes it pass and refactor
-
Switch and repeat
Code Kata
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Improve through repetition / practice
-
http://codekata.com/
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Experiment with constraints (Object Calisthenics, No Ifs etc.)
Checkout Kata
-
Model supermarket checkout
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Scan items and calculate total price
-
Allow for multi-buy offers
Item Unit Special Price Price -------------------------- A 50 3 for 130 B 30 2 for 45 C 20 D 15
From codekata.com - google "checkout kata"
Thoughts?
TDD is a design discpine
-
Encourages Decoupling
-
Interface Focused
-
YAGNI compliant
- Developer Confidence / Happiness
- Ability to change (design and coverage)
- Documentation
- Reduce need to debug
Other Benefits
#IsTDDDead
- Test Induced Design Damage
- Replaced Thoughtfulness
- Applicability to Functional Programming
- Types of problems caught
- Coverage Over-Confidence
- Too many tests
Related Practices
-
Behavior Driven Development
-
Property Based Testing
Good Reads
- TDD by Example - Kent Beck
- Refactoring - Martin Fowler
- Growing Object Oriented Software, Guided by Tests - Steve Freeman & Nat Pryce
- Silk and Spinach blog - Kevin Rutherford
TDD
By Ryan Gough
