Test [and API] driven developmentof CakePHP Behaviors

held by Alexander Morlandat CakeFest 2009

1. Introduction

• Alexander Morland aka 'alkemann'• Web technology since 2005• CakePHP since 2007• illustrata.no 2009

• Revision Behavior• Ordered Behavior• Logable Behavior• and others

1. Introduction2. Unit Testing3. Focus on the API 4. Why we did it5. The Devide and Conquer6. Example7. CakePHP and SimpleTest8. Lessons learned9. Summary

Goal:

Share some of the excitement I discovered in moving the logic to the right place and code it in a way that makes sense. 

Talk overview

In computer programming, unit testing is a software verification and validation method where the programmer gains confidence that individual units of source code are fit for use. A unit is the smallest testable part of an application.

[..] in object-oriented programming, the smallest unit is a method,[..]

from: http://en.wikipedia.org/wiki/Unit_test

• Design• Documentation• Simplifies integration• Facilitates change• Enables Divide and Conquer development

2. Unit Testing

1. Follow existing api 2. Implement abstract classes3. Hook into Cake callbacks4. Keep it simple

Model::delete( $id = NULL, $cascade = true )

delete( $id = NULL, $custom = '', $cascade = true )  vs.delete( $id = NULL, $cascade = true, $custom = '' )

3. API writing

1. Move from single developer to team2. Consistent code, in-house, core and community3. Cyclic development

4. Why we did it?

1. Brainstorm function2. Brainstorm implementation3. Specifications of features4. Write the API5. Parallel or sequential :

o Writing a test caseo Implement code against test

– Write tests for feature specWrite tests trying to use wrongly / error 

– Code Review

5. The Divide and Conquer

What: • add colour on save• easy find by colour

How:• beforeSave()• colour('red')

Tests: • save()• colour()• find()

6. Example - ColourBehavior

Behavior method:

 1. /** 2. * Returns a findByColour of the given colour   3. * 4. * @param Object $Model                         5. * @param $colour Colour to filter model by 6. * @return string a english worded colour       7. */ 8. public function colour(&$Model, $colour) {     9.     return $Model->findAllByColour($colour);10. }                                             

Test code:

 1. $findBy = $Nose->findByColour('red'); 2. $expected = array('Nose' =>                                                           array(0 => array('id' => 3, 'owner' => 'Rudolf', 'colour' => 'Red' )));        3. $this->assertEqual($findBy, $expected, 'Data corrupt : %s'); 4. /**/                                                                             5. $check = $Nose->colour('red'); 6. $this->assertEqual($check, $findBy, 'Different result than findByColour : %s');  7. $this->assertEqual($check, $expected, 'Incorrect result : %s');

Behavior method:

 1. /** 2. * When saving new rows and a colour is not set, insert colour into dataset 3. * It does this by checking if neither id or colour field is in the dataset 4. */                                                                         5. public function beforeSave(&$Model) { 6.     if (                                                                   7.         !isset($Model->data[$Model->alias][$Model->primaryKey]) 8.          &&                                                                9.         !isset($Model->data[$Model->alias]['colour'])10.     ) {                                                                   11.         $Model->data[$Model->alias]['colour'] = $this->random($Model);12.     }                                                                     13.     return true;14. }                                                                         

Test code:

 1. $Nose->create(array('owner' => 'Alexander');  2. $Nose->save();                                                                   3. $result = $Nose->read(); 4. $this->assertNotNull($result['Nose']['colour'], 'Did not get a colour : %s');    5. /**/ 6. $Nose->create(array('owner' => 'Superman', 'colour' => 'Cryptonite');            7. $Nose->save(); 8. $result = $Nose->read();                                                         9. $this->assertEqual($result['Nose']['colour'],'Cryptonite', 'Interference : %s');

Cake uses SimpleTest as vendor (www.simpletest.org)

domain.com/test.php

Run Example

7. CakePHP and SimpleTest

1. Tests could be written blindly2. Usage in focus produced better api3. Complete project just with test4. Shared code early, feedback early5. Test, Brute-force, Optimize6. Start simple and expand7. Test compatibility with other Behaviors8. It was fun!

8. Lessons learned

thanks for listening

Be yourown giant!

In closing