An introduction to Test-Driven Development using FLOW given at the TYPO3 University in Annecy, France in May 2008.

1. TDD (with FLOW3)
Karsten Dambekalns <karsten@typo3.org>
Robert Lemke <robert@typo3.org>
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2. What?
Why?
How?
Integrate!
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3. Test first,
code later

4. Test first, code later
Write tests for all your code
• New features come with a test
• Bugfixes come with a test
Write tests before your code
• Adding a feature means adding a test first
• Fixing a bug means writing a test first
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5. Unit tests
Unit tests are small programs that test your code
They check
• the result of methods against expected values
• whether methods are (not) called as expected
A test should
• be well-named
• check only one assertion
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6. Good tests
Should be...
• automated
• self-contained
• repeatable
• thorough
• small
• talk about the domain
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7. Unit tests
Unit tests are usually run with a test runner
The xUnit family is most widespread
PHPUnit does the job for PHP
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8. Tests aren’t
the goal

9. But you said...

11. They make you feel good

12. They make you feel good
The tests make you
• focus on your task
• code exactly what you need
• think from the outside
• a better programmer*
So what the tests do for you is the key
* decoupling helps with testing,
decoupled code is easier to maintain,
easier is better - q.e.d.
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13. Reasons for TDD
Feel more comfortable
• Build confidence in your code
• Reduce fear of change
(Good) tests are (good) documentation
Acts as safety net
• Regression testing built in
• Helps with refactoring
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14. D for Design
Writing tests first is likely to improve your code
Constant refactoring keeps code clean
Unit testing ensure decoupling
You only code what is really needed
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15. TDD in Practice
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16. The Mantra
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17. The Mantra
Design
Test Test
Implement
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18. More testing
Sometimes you need to test interaction with external systems,
like database access
A test should be small, encapsulated, stand-alone
So how do you test database access?
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19. Mocks & stubs
Mock objects allow you to use fake objects instead of real
implementations
Stubs can be used to return hard-coded results
Using them is actually (somewhat) easy with PHPUnit
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20. Saving in TYPO3CR
Assumptions / Background
• The Session object has a save() method
• It uses a Storage_Backend implementation to do the work
• That implementation has methods like addNode(),
updateNode() and deleteNode()
You need to make sure those are used when calling save()
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21. No FLOW3?
No TDD!

22. No TDD without FLOW3
Without Dependency Injection you cannot really do unit testing
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23. Dependencies
Problem: Classes explicitly refer to other classes:
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24. Dependencies
Try to test this class:
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25. Dependencies
Unit Testing: You want to test a small unit
You don't want to test
• The Simple File Logger
• The Card Repository
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26. Dependencies
Unit Testing: You want to test a small unit
You want to test
• if the action returns a string representation of the
random card it gets from the repository
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27. Dependency Injection
A class doesn't ask for the instance of another class but gets it
injected
This methodology is referred to as the quot;Hollywood Principlequot;:
quot;Don't call us, we'll call youquot;
Enforces loose coupling and high cohesion
Allows you to mock collaborators
Makes you a better programmer
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28. Questions!

29. Links & Literature
Test-Driven Development By Example
Kent Beck, Addison-Wesley
Continuous Integration – Improving Software Quality and
Reducing Risk
Paul M. Duvall, Addison-Wesley
xUnit Test Patterns – Refactoring Test Code
Gerard Meszaros, Addison-Wesley
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30. Links & Literature
FLOW3
http://flow3.typo3.org/
PHPUnit
http://www.phpunit.de/
Hudson CI-Server
https://hudson.dev.java.net/
TYPO3 Forge
http://forge.typo3.org/
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