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Testing untestable CodeStephan Hochdörfer, bitExpert AG
"Quality is a function of thought and reflection -
precise thought and reflection. That’s the magic."
Michael Feathers
Agenda
1. About me
2. Theory
3. How to test untestable code
4. Generating testable code
5. Conclusions
6. Questions
About me
Stephan Hochdörfer, bitExpert AG
Department Manager Research Labs
enjoying PHP since 1999
S.Hochdoerfer@bitExpert.de
@shochdoerfer
No excuse for bad code!
Warning! Use at own risk...
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“?
Theory
What is „untestable code“?
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
Unittest
Requiredclass
Requiredclass
Theory
Class totest
Unittest
Requiredclass
Requiredclass
Database
Externalresource
Requiredclass
Requiredclass
Webservice
Theory
Class totest
Unittest
Requiredclass
Requiredclass
Database
Externalresource
Requiredclass
Requiredclass
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...
Testing „untestable“ PHP Code
For your safty!
Do not change existing code!
Testing „untestable“ PHP Code | __autoload
<?phpclass Car {
private $Engine;
public function __construct($sEngine) {$this->Engine = Engine::getByType($sEngine);
}
}
Testing „untestable“ PHP Code | __autoload
How to inject a dependency? Use __autoload
<?phpclass Car {
private $Engine;
public function __construct($sEngine) {$this->Engine = Engine::getByType($sEngine);
}
}
Testing „untestable“ PHP Code | __autoload
<?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 $Engine;
public function __construct($sEngine) {$this->Engine = Engine::getByType($sEngine);
}}
Testing „untestable“ PHP Code | include_path
<?phpinclude('Engine.php');
class Car {private $Engine;
public function __construct($sEngine) {$this->Engine = Engine::getByType($sEngine);
}}
How to inject a dependency? Manipulate include_path setting
Testing „untestable“ PHP Code | include_path
<?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
<?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');
Source: Alex Netkachov, http://www.alexatnet.com/node/203
Testing „untestable“ PHP Code | include_path alternative
<?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', 'MockedEngine::get', $content);return $content;
}}
stream_wrapper_unregister('file');stream_wrapper_register('file', 'CustomFileStreamWrapper');
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);
}}
Testing „untestable“ PHP Code | vfsStream
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);
}}
Testing „untestable“ PHP Code | vfsStream
<?php
// setup vfsStreamvfsStreamWrapper::register();vfsStreamWrapper::setRoot(new vfsStreamDirectory('app'));
$oCar = new Car('Diesel', vfsStream::url('app'));
echo vfsStreamWrapper::getRoot()->hasChild('cache');
Testing „untestable“ PHP Code
„I have no idea how to unit-test procedural code. Unit-testing assumes that I can instantiate a piece of my application in
isolation.“ Miško Hevery
Testing „untestable“ PHP Code | Test functions
<?phpfunction startsWith($sString, $psPre) {
return $psPre == substr($sString, 0, strlen($psPre));}
function contains($sString, $sSearch) {return false !== strpos($sString, $sSearch);
}
Testing „untestable“ PHP Code | Test functions
How to test PHPUnit can call functions PHPUnit can save/restore globale state
<?phpfunction startsWith($sString, $psPre) {
return $psPre == substr($sString, 0, strlen($psPre));}
function contains($sString, $sSearch) {return false !== strpos($sString, $sSearch);
}
Testing „untestable“ PHP Code | overwrite internal functions
<?phpfunction buyCar(Car $oCar) {
global $oDB;
mysql_query("INSERT INTO...", $oDB);
mail('order@domain.org', 'New sale', '....');}
Testing „untestable“ PHP Code | overwrite internal functions
<?phpfunction buyCar(Car $oCar) {
global $oDB;
mysql_query("INSERT INTO...", $oDB);
mail('order@domain.org', 'New sale', '....');}
How to test Do not load mysql extension. Provide own implementation Unfortunatley mail() is part of the PHP core
Testing „untestable“ PHP Code | overwrite internal functions
<?phpfunction buyCar(Car $oCar) {
global $oDB;
mysql_query("INSERT INTO...", $oDB);
mail('order@domain.org', 'New sale', '....');}
How to test Use classkit extension to overwrite internal functions
Testing „untestable“ PHP Code | overwrite internal functions
<?php
ini_set('runkit.internal_override', '1');
runkit_function_redefine('mail','','return true;');
?>
Testing „untestable“ PHP Code
Generative Programming
Generating testable code
Generative Programming
Generating testable code
Configuration
Implementationcomponents
Generatorapplication
ProductGenerator
1 ... n
Generative Programming
Generating testable code
Configuration
Implementationcomponents
Generatorapplication
Application
Generator
Testcases
Course of action
Extraction „Mask“ parts of the code
Customizing Change content of global vars Pre/Postfixes for own functions, methods, classes
Recombine Re-order parts of the code
Generating testable code
Generating testable code
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()<?phpfunction buyCar(Car $oCar) {global $oDB;
<!{Prefix}!>mysql_query(„INSERT INTO...“, $oDB);<!{MailSlot}!>}
?>ENDCONTENT() }}
Generating testable code
<?phpfunction buyCar(Car $oCar) { global $oDB;
test_mysql_query("INSERT INTO...", $oDB);}
1. Example
Prefix: test_
Generating testable code
<?phpfunction buyCar(Car $oCar) { global $oDB;
test_mysql_query("INSERT INTO...", $oDB);}
<?phpfunction buyCar(Car $oCar) { global $oDB;
mysql_query("INSERT INTO...", $oDB); mail('order@domain.org', 'New sale', '....');}
?>
1. Example
Prefix: test_
2. Example
MailSlot: mail('order@domain.org', 'New sale', '....');
Conclusion
How much effort to take?
Conclusion
Conclusion
Change mindset to write testable code Dependency Injection
Look for other options to raise the bar Work around limitations of PHP PHP is flexible, use it that way
http://joind.in/1545
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