Testing untestable code
Stephan Hochdörfer, bitExpert AG

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

Testing untestable code
No excuse for writing bad code!

Testing untestable code
Not to freak out!

Testing untestable code
Creativity matters!

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

Testing untestable code
What is „untestable code“?

Testing untestable code
Wrong object construction
“new” is evil!
s

Testing untestable code
Tight coupling

Testing untestable code
Uncertainty

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

Testing untestable code
In a perfect world...
Unittest
Unittest SUT
SUT

Testing untestable code
Legacy code is not perfect...
Dependency
Dependency
Unittest
Unittest SUT
SUT
Dependency
Dependency

Testing untestable code
...
Legacy code is not perfect...
Dependency
Dependency
Unittest
Unittest SUT
SUT
Dependency
Dependency
...

Testing untestable code
...
Legacy code is not perfect...
Dependency
Dependency
Unittest
Unittest SUT
SUT
Dependency
Dependency
...

Testing untestable code
How to get „testable“ code?

Testing untestable code
How to get „testable“ code?
Refactoring

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

Testing untestable code
Hope? - Nope...

Testing untestable code
Which path to take?

Testing untestable code
Which path to take?
Do not change existing code!

Testing untestable code
Examples
Object construction External resources Language issues

Testing untestable code
Object construction
<?php
class Car {
private $Engine;
public function __construct($sEngine) {
$this->Engine = Engine::getByType($sEngine);
}
}

Testing untestable code
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');

Testing untestable code
Object construction
<?php
include('Engine.php');
class Car {
private $Engine;
public function __construct($sEngine) {
$this->Engine = Engine::getByType($sEngine);
}
}

Testing untestable code
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();

Testing untestable code
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;
}
}

Testing untestable code
Object construction – Stream Wrapper
stream_wrapper_unregister('file');
stream_wrapper_register('file', 'CustomWrapper');

Testing untestable code
Object construction – Stream Wrapper
<?php
class CustomWrapper {
private $_handler ;
function stream_read( $count ) {
$content = fread($this->_handler, $count );
$content = str_replace ('Engine::getByType' ,
' Abstract Engine::get' , $content );
return $content ;
}
}

Testing untestable code
Object construction – Namespaces
<?php
class Car {
private $Engine;
public function __construct($sEngine) {
$this->Engine = CarEngine::
getByType($sEngine);
}
}

Testing untestable code
External resources

Testing untestable code
External resources
Database Webservice
Filesystem Mailserver

Testing untestable code
External resources – Mock database

Testing untestable code
External resources – Mock database
Provide own implementation

Testing untestable code
External resources – Mock database
ZF example:
$db = new Custom_Db_Adapter(array());
Zend_Db_Table::setDefaultAdapter($db);

Testing untestable code
External resources – Mock database
PHPUnit_Extensions_Database_TestCase

Testing untestable code
External resources – Mock database
Proxy for your SQL Server

Testing untestable code
External resources – Mock webservice

Testing untestable code
External resources – Mock webservice
Provide own implementation

Testing untestable code
External resources – Mock webservice
Host redirect via /etc/hosts

Testing untestable code
External resources – Mock filesystem

Testing untestable code
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');

Testing untestable code
External resources – Mock Mailserver

Testing untestable code
External resources – Mock Mailserver
Use fake mail server

Testing untestable code
External resources – Mock Mailserver
$ cat /etc/php5/php.ini | grep sendmail_path
sendmail_path=/usr/local/bin/logmail
$ cat /usr/local/bin/logmail
cat >> /tmp/logmail.log

Testing untestable code
Dealing with language issues

Testing untestable code
Dealing with language issues
Testing your privates?

Testing untestable code
Dealing with language issues
<?php
class CustomWrapper {
private $_handler;
function stream_read($count) {
$content = fread($this->_handler, $count);
$content = str_replace(
'private function',
'public function',
$content
);
return $content;
}

Testing untestable code
Dealing with language issues
$myClass = new MyClass();
$reflectionClass = new ReflectionClass('MyClass');
$reflectionMethod = $reflectionClass->
getMethod('mydemo');
$reflectionMethod->setAccessible(true);
$reflectionMethod->invoke($myClass);

Testing untestable code
Dealing with language issues
Overwrite internal functions?

Testing untestable code
Dealing with language issues
pecl install runkit-0.9

Testing untestable code
Dealing with language issues - Runkit
<?php
ini_set('runkit.internal_override', '1');
runkit_function_redefine('mail','','return
true;');
?>

Testing untestable code
What else?

Testing untestable code
What else?
Generative Programming

Testing untestable code
Generative Programming
Configuration
Configuration
1 ... n
Implementation
Implementation Generator
Generator Product
components
components Product
Generator
Generator
application
application

Testing untestable code
Generative Programming
Configuration
Configuration
Application
Application
Implementation
Implementation Generator
Generator
components
components
Testcases
Testcases
Generator
Generator
application
application

Testing untestable code
Generative Programming
A frame is a data structure
for representing knowledge.

Testing untestable code
A Frame instance
<?php
class Car {
private $Engine;
public function __construct($sEngine) {
$this->Engine = <!{Factory}!>::
getByType($sEngine);
}
}

Testing untestable code
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");
}
}
}

Testing untestable code
Generated result - Testcase
<?php
class Car {
private $Engine;
public function __construct($sEngine) {
$this->Engine = FactoryMock::
getByType($sEngine);
}
}

Testing untestable code
Generated result - Application
<?php
class Car {
private $Engine;
public function __construct($sEngine) {
$this->Engine = EngineFactory::
getByType($sEngine);
}
}

Testing untestable code
What is possible?

Testing untestable code
What is possible?
Show / hide parts of the code

Testing untestable code
What is possible?
Change content of global vars!

Testing untestable code
What is possible?
Define pre- or postfixes!

Testing untestable code
Is it worth it?

Testing untestable code
Conclusions
Change your mindset to write
testable code!

Testing untestable code
Conclusions
PHP is a swiss-army knife.
Use it that way!

http://joind.in/3026