Testing untestable code - PHPBNL11

Testing untestable code
Stephan 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

 S.Hochdoerfer@bitExpert.de

 @shochdoerfer

Warning! Use at your own risk...

No excuse for writing bad code!

Theory

"There is no secret to writing tests, there
are only secrets to write testable code!"
Miško Hevery

Theory

What is „untestable code“?

Theory

What is „untestable code“?

s

„new“ is evil!

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

Required
Required
class
class
Class to
Unittest Class to
Unittest Test
Test
Required
Required
class
class

Theory

Database
Database
Required
Required
class
class
External
Class to External
Unittest Class to resource
Unittest test resource
test
Required
Required
class
class

Required Required
Required Required Webservice
class class Webservice
class class

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

<?php
class Car {
private $Engine;

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

}


<?php
class Car {
private $Engine;

}

}

How to inject a dependency?
 Use __autoload


<?php
function run_autoload($psClass) {
$sFileToInclude = strtolower($psClass).'.php';
if(strtolower($psClass) == 'engine') {
$sFileToInclude = '/custom/mocks/'.$sFileToInclude;
}
include($sFileToInclude);
}

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

Testing „untestable“ PHP Code | include_path

<?php
include('Engine.php');

class Car {
private $Engine;

}
}


<?php

class Car {
private $Engine;

}
}

 Manipulate include_path setting


<?php
ini_set('include_path',
'/custom/mocks/'.PATH_SEPARATOR.
ini_get('include_path'));

// Testcase
include('car.php');

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

Testing „untestable“ PHP Code | include_path alternative

<?php

class Car {
private $Engine;

}
}


<?php

class Car {
private $Engine;

}
}

 Custom Stream Wrapper behaviour

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


<?php
class 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) {}
}



<?php
private $_handler;

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

<?php
private $_handler;

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

<?php
class Car {
private $Engine;

$this->Engine = CarEngine::getByType($sEngine);
}
}

Testing „untestable“ PHP Code | Namespaces

<?php
class Car {
private $Engine;

}
}

 Use __autoload or manipulate the include_path

Testing „untestable“ PHP Code | vfsStream

<?php
class Car {
private $Engine;

public function __construct($sEngine, $CacheDir) {

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


<?php
class Car {
private $Engine;

public function __construct($sEngine, $CacheDir) {

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

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


<?php

// setup vfsStream
vfsStreamWrapper::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

<?php
function startsWith($sString, $psPre) {
return $psPre == substr($sString, 0, strlen($psPre));
}

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


<?php
}

}

How to test
 PHPUnit can call functions


<?php
}

}

How to test
 PHPUnit can call functions

 PHPUnit can save/restore globale state

Testing „untestable“ PHP Code | overwrite internal functions

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

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

mail('order@domain.org', 'New sale', '....');
}


<?php
global $oDB;


}

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


<?php
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;');

?>

Generating testable code

What else?

Remember:
No changes to the source code!


What else?

Generative Programming



Configuration
Configuration

1 ... n
Implementation
Implementation Generator Product
components Generator Product
components

Generator
Generator
application
application



Configuration
Configuration

Application
Application

Implementation
Implementation Generator
components Generator
components

Testcases
Testcases
Generator
Generator
application
application



A frame is a data structure
for representing knowledge.


FileFrm FILEIndex_php5 {
private String Prefix = "test_";
private String MailSlot = "mail('order@domain.org', 'New sale', '....');";

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

private void assign() {
BEGINCONTENT()
<?php
global $oDB;

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

?>
ENDCONTENT()
}
}


Extraction
 Show / hide parts of the code

Example
MailSlot: mail('order@domain.org', 'New sale', '....');


Extraction
 Show / hide parts of the code

Example
MailSlot: mail('order@domain.org', 'New sale', '....');

<?php
global $oDB;

}

?>


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

Example
Prefix: test_


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

Example
Prefix: test_

<?php
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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