testing untestable code - phpbnl11

Testing untestable codeStephan Hochdörfer, bitExpert AG

"Quality is a function of thought and reflection -

precise thought and reflection. That’s the magic."

Michael Feathers

About me

Stephan Hochdörfer, bitExpert AG

Department Manager Research Labs

enjoying PHP since 1999

[email protected]

@shochdoerfer

Warning! Use at your own risk...

No excuse for writing bad code!

Seriously, I am not kidding!

Theory

"There is no secret to writing tests, there

are only secrets to write testable code!"Miško Hevery

Theory

What is „untestable code“?

s

Theory


„new“ is evil!

Theory


Theory

"...our test strategy requires us to have more control or

visibility of the internal behavior of the system under test."Gerard Meszaros, xUnit Test Patterns: Refactoring Test Code

Theory

Class toTest

Class toTestUnittest

Unittest

Requiredclass

Requiredclass

Requiredclass

Requiredclass

Theory

Class totest

Class totestUnittest

Unittest

Requiredclass

Requiredclass

Requiredclass

Requiredclass

DatabaseDatabase

Externalresource

Externalresource

Requiredclass

RequiredclassRequired

class

Requiredclass Webservice

Webservice

Theory

How to achieve „testable“ code?

Theory

How to achieve „testable“ code?

Refactoring

Theory

"Before you start refactoring, check that you

have a solid suite of tests."Martin Fowler, Refactoring

Testing „untestable“ PHP Code

Let the work begin...


Safty instructions

Do not change existing code!

Testing „untestable“ PHP Code | __autoload

<?phpclass Car {

private $Engine;

public function __construct($sEngine) {$this->Engine = Engine::getByType($sEngine);

}

}


How to inject a dependency? Use __autoload

<?phpclass Car {

private $Engine;


}

}


<?phpfunction run_autoload($psClass) {

$sFileToInclude = strtolower($psClass).'.php';if(strtolower($psClass) == 'engine') {

$sFileToInclude = '/custom/mocks/'.$sFileToInclude;}include($sFileToInclude);

}

// Testcasespl_autoload_register('run_autoload');$oCar = new Car('Diesel');echo $oCar->run();

Testing „untestable“ PHP Code | include_path

<?phpinclude('Engine.php');

class Car {private $Engine;


}}





}}

How to inject a dependency? Manipulate include_path setting


<?phpini_set('include_path',

'/custom/mocks/'.PATH_SEPARATOR.ini_get('include_path'));

// Testcaseinclude('car.php');

$oCar = new Car('Diesel');echo $oCar->run();

Testing „untestable“ PHP Code | include_path alternative




}}





}}

How to inject a dependency? Custom Stream Wrapper behaviour

Idea by Alex Netkachov, http://www.alexatnet.com/node/203


<?phpclass CustomFileStreamWrapper { private $_handler;

function stream_open($path, $mode, $options, &$opened_path) { stream_wrapper_restore('file');

// @TODO: modify $path before fopen $this->_handler = fopen($path, $mode); stream_wrapper_unregister('file'); stream_wrapper_register('file', 'CustomFileStreamWrapper'); return true; }

function stream_read($count) {}

function stream_write($data) {}

function stream_tell() {}

function stream_eof() {}

function stream_seek($offset, $whence) {}}

stream_wrapper_unregister('file');stream_wrapper_register('file', 'CustomFileStreamWrapper');


<?phpclass CustomFileStreamWrapper {

private $_handler;

function stream_open($path, $mode, $options, &$opened_path) {stream_wrapper_restore('file');$this->_handler = fopen($path, $mode);stream_wrapper_unregister('file');stream_wrapper_register('file', 'CustomFileStreamWrapper');return true;

}

function stream_read($count) {$content = fread($this->_handler, $count);$content = str_replace('Engine::getByType', 'AbstractEngine::get',

$content);return $content;

}}


include('engine.php');?>


How to test private methods?



There`s no need to!



There`s no need to, but...

Testing „untestable“ PHP Code | private vs. protected

<?phpclass CustomFileStreamWrapper {

private $_handler;

function stream_open($path, $mode, $options, &$opened_path) {stream_wrapper_restore('file');$this->_handler = fopen($path, $mode);stream_wrapper_unregister('file');stream_wrapper_register('file', 'CustomFileStreamWrapper');return true;

}

function stream_read($count) {$content = fread($this->_handler, $count);$content = str_replace('private function', 'public function',

$content);return $content;

}}


include('engine.php');?>

Testing „untestable“ PHP Code | Namespaces

<?phpclass Car {

private $Engine;

public function __construct($sEngine) {$this->Engine = \Car\Engine::getByType($sEngine);

}}

Testing „untestable“ PHP Code | Namespaces

<?phpclass Car {

private $Engine;

public function __construct($sEngine) {$this->Engine = \Car\Engine::getByType($sEngine);

}}

How to inject a dependency? Use __autoload or manipulate the include_path

Testing „untestable“ PHP Code | vfsStream

<?phpclass Car {

private $Engine;

public function __construct($sEngine, $CacheDir) {$this->Engine = \Car\Engine::getByType($sEngine);

mkdir($CacheDir.'/cache/', 0700, true);}

}


How mock a filesystem? Use vfsStream - http://code.google.com/p/bovigo/

<?phpclass Car {

private $Engine;

public function __construct($sEngine, $CacheDir) {$this->Engine = \Car\Engine::getByType($sEngine);

mkdir($CacheDir.'/cache/', 0700, true);}

}


<?php

// setup vfsStreamvfsStreamWrapper::register();vfsStreamWrapper::setRoot(new vfsStreamDirectory('app'));

$oCar = new Car('Diesel', vfsStream::url('app'));

echo vfsStreamWrapper::getRoot()->hasChild('cache');

Testing „untestable“ PHP Code | Database

Database Testing

Use the methods provided by your favourite framework

e.g Zend Framework

Implement Zend_Db_Statement_Interface

subclass Zend_Db_Adapter_Abstract

$db = new Custom_Db_Adapter(array());Zend_Db_Table::setDefaultAdapter($db);


Database Testing

For low-level database access:

e.g MySQL

do not load the mysql extension

Add custom userland implementations of mysql_* functions


Database Testing

Use the methods provided by your favourite unittest framework

e.g PHPUnit

extend PHPUnit_Extensions_Database_TestCase

implement getConnection() and getDataset()


Database Testing

Use the methods provided by your favourite sql server (and tools)

e.g MySQL

use MySQL Proxy to transparently switch databases

Begin and rollback transactions


„I have no idea how to unit-test procedural code. Unit-testing assumes that I can instantiate a piece of my application in

isolation.“ Miško Hevery

Testing „untestable“ PHP Code | Test functions

<?phpfunction startsWith($sString, $psPre) {

return $psPre == substr($sString, 0, strlen($psPre));}

function contains($sString, $sSearch) {return false !== strpos($sString, $sSearch);

}


How to test PHPUnit can call functions




}


How to test PHPUnit can call functions

PHPUnit can save/restore globale state




}

Testing „untestable“ PHP Code | overwrite internal functions

<?phpfunction buyCar(Car $oCar) {

global $oDB;

mysql_query("INSERT INTO...", $oDB);

mail('[email protected]', 'New sale', '....');}



global $oDB;



How to test Unfortunatley mail() is part of the PHP core and cannot be unloaded



global $oDB;



How to test Use classkit extension to overwrite internal functions


<?php

ini_set('runkit.internal_override', '1');

runkit_function_redefine('mail','','return true;');

?>

What else?

Generating testable code

Remember: No changes to the source code!

What else?


Generative Programming



ConfigurationConfiguration

Implementationcomponents


Generatorapplication


ProductProductGenerator

Generator

1 ... n



ConfigurationConfiguration





ApplicationApplication

GeneratorGenerator

TestcasesTestcases



A frame is a data structure for representing knowledge.


FileFrm FILEIndex_php5 { private String Prefix = "test_"; private String MailSlot = "mail('[email protected]', 'New sale', '....');";

public FILEIndex_php5() {setFilename("index.php5");setRelativePath("/");

}

private void assign() {BEGINCONTENT()<?phpfunction buyCar(Car $oCar) {global $oDB;

<!{Prefix}!>mysql_query(„INSERT INTO...“, $oDB);<!{MailSlot}!>}

?>ENDCONTENT() }}



Extraction Show / hide parts of the code

ExampleMailSlot: mail('[email protected]', 'New sale', '....');



Extraction Show / hide parts of the code

ExampleMailSlot: mail('[email protected]', 'New sale', '....');

<?phpfunction buyCar(Car $oCar) { global $oDB;

mysql_query("INSERT INTO...", $oDB); mail('[email protected]', 'New sale', '....');}

?>


Course of action

Customizing Change content of global vars Pre/Postfixes for own functions, methods, classes

ExamplePrefix: test_


Course of action

Customizing Change content of global vars Pre/Postfixes for own functions, methods, classes

ExamplePrefix: test_

<?phpfunction buyCar(Car $oCar) { global $oDB;

test_mysql_query("INSERT INTO...", $oDB);}

Conclusion

How much effort to take?

Conclusion

Conclusion

Change your mindset to write testable code!

Conclusion

Conclusion

PHP is a swiss army knife.

http://joind.in/2420

testing untestable code - phpbnl11

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