tdd (with flow3)

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TDD (with FLOW3)Karsten Dambekalns <karsten@typo3.org>

Robert Lemke <robert@typo3.org>

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What?Why?How?

Integrate!

Test first,code later

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Test first, code laterWrite 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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Unit testsUnit 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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Good testsShould be...

• automated

• self-contained

• repeatable

• thorough

• small

• talk about the domain

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Unit testsUnit tests are usually run with a test runner

The xUnit family is most widespread

PHPUnit does the job for PHP

Tests aren’tthe goal

But you said...

They make you feel good

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They make you feel goodThe 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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Reasons for TDDFeel 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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D for DesignWriting 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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TDD in Practice

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The Mantra

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The Mantra

Implement

Test Test

Design

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More testingSometimes 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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Mocks & stubsMock 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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Saving in TYPO3CRAssumptions / 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()

No FLOW3?No TDD!

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No TDD without FLOW3Without Dependency Injection you cannot really do unit testing

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DependenciesProblem: Classes explicitly refer to other classes:

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DependenciesTry to test this class:

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DependenciesUnit 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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DependenciesUnit 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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Dependency InjectionA class doesn't ask for the instance of another class but gets it injected

This methodology is referred to as the "Hollywood Principle":"Don't call us, we'll call you"

Enforces loose coupling and high cohesion

Allows you to mock collaborators

Makes you a better programmer

Questions!

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Test-Driven Development By ExampleKent Beck, Addison-Wesley

Links & Literature

Continuous Integration – Improving Software Quality and Reducing RiskPaul M. Duvall, Addison-Wesley

xUnit Test Patterns – Refactoring Test CodeGerard Meszaros, Addison-Wesley

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Links & LiteratureFLOW3http://flow3.typo3.org/

PHPUnithttp://www.phpunit.de/

Hudson CI-Serverhttps://hudson.dev.java.net/

TYPO3 Forgehttp://forge.typo3.org/