Testing untestable code - phpconpl11

Testing untestable code

About me

 Stephan Hochdörfer, bitExpert AG
 Department Manager Research Labs
 enjoying PHP since 1999
 S.Hochdoerfer@bitExpert.de
 @shochdoerfer


No excuse for writing bad code!


Not to freak out!


Creativity matters!


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


What is „untestable Code“?


1. Wrong object construction

“new” is evil!
s


2. Tight coupling


No code reuse!


No isolation → not testable!


3. Uncertainty


"...our test strategy requires us to
have more control [...] of the sut."
Gerard Meszaros, xUnit Test Patterns: Refactoring Test
Code


In a perfect world...

Unittest
Unittest SUT
SUT


Legacy code is not perfect...

Dependency
Dependency

Unittest
Unittest SUT
SUT

Dependency
Dependency

...
Legacy code is not perfect...

Dependency
Dependency

Unittest
Unittest SUT
SUT

Dependency
Dependency

...


How to get „testable“ code?


How to get „testable“ code?

Refactoring


"Before you start refactoring, check
that you have a solid suite of tests."
Martin Fowler, Refactoring


Hope? - Nope...


Which path to take?


Which path to take?

Do not change existing code!


Examples

Object Construction External resources Language issues


Object construction
<?php
class Car {
private $Engine;

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

}


Object construction - 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');


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

class Car {
private $Engine;

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


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

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

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


Object construction – Stream Wrapper
<?php
class CustomWrapper {
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', 'CustomWrapper');
return true;
}
}


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


<?php
private $_handler ;

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


Object construction – Namespaces
<?php
class Car {
private $Engine;

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


External resources


External resources

Database Webservice

Filesystem Mailserver


External resources – Mock database



Provide own implementation



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



PHPUnit_Extensions_Database_TestCase



Proxy for your SQL Server


External resources – Mock webservice



Provide own implementation



Host redirect via /etc/hosts


External resources – Mock filesystem


External resources – Mock filesystem
<?php

// set up test environmemt
vfsStream::setup('exampleDir');

// create directory in test enviroment
mkdir(vfsStream::url('exampleDir').'/sample/');

// check if directory was created
echo vfsStreamWrapper::getRoot()->hasChild('sample');


External resources – Mock Mailserver



Use fake mail server



$ cat /etc/php5/php.ini | grep sendmail_path
sendmail_path=/usr/local/bin/logmail

$ cat /usr/local/bin/logmail
cat >> /tmp/logmail.log


Dealing with language issues



Testing your privates?


<?php
private $_handler;

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


$myClass = new MyClass();

$reflectionClass = new ReflectionClass('MyClass');
$reflectionMethod = $reflectionClass->
getMethod('mydemo');
$reflectionMethod->setAccessible(true);
$reflectionMethod->invoke($myClass);



Overwrite internal functions?



pecl install runkit-0.9


Dealing with language issues - Runkit
<?php

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

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

?>



pecl install funcall-0.3.0alpha


Dealing with language issues - Funcall
<?php
function my_func($arg1, $arg2) {
return $arg1.$arg2;
}

function post_cb($args,$result,$process_time) {
// return custom result based on $args
}

fc_add_post('my_func','post_cb');
var_dump(my_func('php', 'c'));


What else?


What else?

Generative Programming



Configuration
Configuration

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

Generator
Generator
application
application



Configuration
Configuration

Application
Application

Implementation
Implementation Generator
Generator
components
components

Testcases
Testcases
Generator
Generator
application
application



A frame is a data structure
for representing knowledge.


A Frame instance
<?php
class Car {
private $Engine;

$this->Engine = <!{Factory}!>::
}

}


The Frame controller

public class MyFrameController extends
SimpleFrameController {

public void execute(Frame frame, FeatureConfig
config) {
if(config.hasFeature("unittest")) {
frame.setSlot("Factory", "FactoryMock");
}
else {
frame.setSlot("Factory", "EngineFactory");
}
}
}


Generated result - Testcase
<?php
class Car {
private $Engine;

$this->Engine = FactoryMock::
}

}


Generated result - Application
<?php
class Car {
private $Engine;

$this->Engine = EngineFactory::
}

}


What is possible?


What is possible?

Show / hide parts of the code


What is possible?

Change content of global vars!


What is possible?

Define pre- or postfixes!


Is it worth it?


Conclusions

Change your mindset to write
testable code!


Conclusions

PHP is a swiss-army knife.
Use it that way!

http://joind.in/3922


Bildquellen

http://www.flickr.com/photos/andresrueda/3452940751/
http://www.flickr.com/photos/andresrueda/3455410635/

Testing untestable code - phpconpl11

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