Testing untestable code - oscon 2012

Testing untestable code
Stephan Hochdörfer, bitExpert AG


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!


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


What is „untestable code“?


"...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


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');
echo $oCar>run();


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',
'AbstractEngine::get', $content);
return $content;
}
}


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'));



funcall for methods?



git clone https://github/juliens/AOP


Dealing with language issues - AOP
<?php

aop_add_after('Car::drive*',
'adviceForDrive');


Dealing with language issues - AOP
<?php

$advice = function(AopTriggeredJoinpoint
$jp) {
  $returnValue =
     $jp>getReturnedValue();

  // modify the return value
  $returnValue = 1234;

  $jp>setReturnedValue($returnValue);
};

aop_add_after('Car>drive()', $advice);


What else?

Generative Programming



Configuration
Configuration
(DSL)
(DSL)

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



Configuration
Configuration
(DSL)
(DSL)
Customer 22
Customer

Implementation-
Implementation-
components
Generator
Generator Customer 11
components Customer



Configuration
Configuration
(DSL)
(DSL)
Test
Test
Enviroment
Enviroment

Implementation-
Implementation-
components
Generator
Generator Prod.
Prod.
components Enviroment
Enviroment



A frame is a data structure
for representing knowledge.


Frame
<?php
class Car {
private $Engine;

$this>Engine = <!{Factory}!>::
getByType($sEngine);
}

}


ContentProvider for the Frame
public class MyContentProvider extends
    AbstractContentProvider {
    public SlotConfiguration computeSlots(
        FeatureConfiguration config) {
        SlotConfiguration sl = new SlotConfiguration();

        if(config.hasFeature("unittest")) {
            sl.put("Factory", "FactoryMock");
        } else {
            sl.put("Factory", "EngineFactory");
        }
        return sl;
    }
}


Generated result – Test Enviroment
<?php
class Car {
private $Engine;

$this>Engine = FactoryMock::
}

}


Generated result – Prod. Enviroment
<?php
class Car {
private $Engine;

$this>Engine = EngineFactory::
}

}


Curious for more?

http://replicatorframework.org

Please rate: http://bit.ly/ML0alS

Testing untestable code - oscon 2012

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