The document discusses testing untestable code. It begins by defining untestable code as code that is difficult to test in isolation without dependencies like databases or external resources. It then provides several techniques for making code more testable such as using dependency injection, manipulating include paths, and mocking dependencies. Specific examples are given for techniques like overriding internal functions and using stream wrappers to mock includes. The talk emphasizes writing testable code from the beginning through principles like dependency injection and avoiding direct dependencies where possible.

1. 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

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

3. Warning! Use at your own risk...

4. No excuse for writing bad code!

5. Seriously, I am not kidding!

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

7. Theory
What is „untestable code“?

8. Theory
What is „untestable code“?
s
„new“ is evil!

9. Theory
What is „untestable code“?

10. Theory
What is „untestable code“?

11. 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

12. Theory
Required
Required
class
class
Class to
Unittest Class to
Unittest Test
Test
Required
Required
class
class

13. 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

14. 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

15. Theory
How to achieve „testable“ code?

16. Theory
How to achieve „testable“ code?
Refactoring

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

18. Testing „untestable“ PHP Code
Let the work begin...

19. Testing „untestable“ PHP Code
Safty instructions
Do not change existing code!

20. Testing „untestable“ PHP Code | __autoload
<?php
class Car {
private $Engine;
public function __construct($sEngine) {
$this->Engine = Engine::getByType($sEngine);
}
}

21. Testing „untestable“ PHP Code | __autoload
<?php
class Car {
private $Engine;
public function __construct($sEngine) {
$this->Engine = Engine::getByType($sEngine);
}
}
How to inject a dependency?
 Use __autoload

22. Testing „untestable“ PHP Code | __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();

23. Testing „untestable“ PHP Code | include_path
<?php
include('Engine.php');
class Car {
private $Engine;
public function __construct($sEngine) {
$this->Engine = Engine::getByType($sEngine);
}
}

24. Testing „untestable“ PHP Code | include_path
<?php
include('Engine.php');
class Car {
private $Engine;
public function __construct($sEngine) {
$this->Engine = Engine::getByType($sEngine);
}
}
How to inject a dependency?
 Manipulate include_path setting

25. Testing „untestable“ PHP Code | 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();

26. Testing „untestable“ PHP Code | include_path alternative
<?php
include('Engine.php');
class Car {
private $Engine;
public function __construct($sEngine) {
$this->Engine = Engine::getByType($sEngine);
}
}

27. Testing „untestable“ PHP Code | include_path alternative
<?php
include('Engine.php');
class Car {
private $Engine;
public function __construct($sEngine) {
$this->Engine = Engine::getByType($sEngine);
}
}
How to inject a dependency?
 Custom Stream Wrapper behaviour
 Idea by Alex Netkachov, http://www.alexatnet.com/node/203

28. Testing „untestable“ PHP Code | include_path alternative
<?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) {}
}
stream_wrapper_unregister('file');
stream_wrapper_register('file', 'CustomFileStreamWrapper');

29. Testing „untestable“ PHP Code | include_path alternative
<?php
class 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', 'AbstractEngine::get',
$content);
return $content;
}
}
stream_wrapper_unregister('file');
stream_wrapper_register('file', 'CustomFileStreamWrapper');
include('engine.php');
?>

30. Testing „untestable“ PHP Code
How to test private methods?

31. Testing „untestable“ PHP Code
How to test private methods?
There`s no need to!

32. Testing „untestable“ PHP Code
How to test private methods?
There`s no need to, but...

33. Testing „untestable“ PHP Code | private vs. protected
<?php
class 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('private function', 'public function',
$content);
return $content;
}
}
stream_wrapper_unregister('file');
stream_wrapper_register('file', 'CustomFileStreamWrapper');
include('engine.php');
?>

34. Testing „untestable“ PHP Code | Namespaces
<?php
class Car {
private $Engine;
public function __construct($sEngine) {
$this->Engine = CarEngine::getByType($sEngine);
}
}

35. Testing „untestable“ PHP Code | Namespaces
<?php
class Car {
private $Engine;
public function __construct($sEngine) {
$this->Engine = CarEngine::getByType($sEngine);
}
}
How to inject a dependency?
 Use __autoload or manipulate the include_path

36. Testing „untestable“ PHP Code | vfsStream
<?php
class Car {
private $Engine;
public function __construct($sEngine, $CacheDir) {
$this->Engine = CarEngine::getByType($sEngine);
mkdir($CacheDir.'/cache/', 0700, true);
}
}

37. Testing „untestable“ PHP Code | vfsStream
<?php
class Car {
private $Engine;
public function __construct($sEngine, $CacheDir) {
$this->Engine = CarEngine::getByType($sEngine);
mkdir($CacheDir.'/cache/', 0700, true);
}
}
How mock a filesystem?
 Use vfsStream - http://code.google.com/p/bovigo/

38. Testing „untestable“ PHP Code | vfsStream
<?php
// setup vfsStream
vfsStreamWrapper::register();
vfsStreamWrapper::setRoot(new vfsStreamDirectory('app'));
$oCar = new Car('Diesel', vfsStream::url('app'));
echo vfsStreamWrapper::getRoot()->hasChild('cache');

39. 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);

40. Testing „untestable“ PHP Code | Database
Database Testing
 For low-level database access:
 e.g MySQL
 do not load the mysql extension
 Add custom userland implementations of mysql_* functions

41. Testing „untestable“ PHP Code | Database
Database Testing
 Use the methods provided by your favourite unittest framework
 e.g PHPUnit
 extend PHPUnit_Extensions_Database_TestCase
 implement getConnection() and getDataset()

42. Testing „untestable“ PHP Code | Database
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

43. 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

44. 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);
}

45. 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);
}
How to test
 PHPUnit can call functions

46. 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);
}
How to test
 PHPUnit can call functions
 PHPUnit can save/restore globale state

47. 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', '....');
}

48. 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', '....');
}

49. 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', '....');
}
How to test
 Unfortunatley mail() is part of the PHP core and cannot be unloaded

50. 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', '....');
}
How to test
 Use classkit extension to overwrite internal functions

51. Testing „untestable“ PHP Code | overwrite internal functions
<?php
ini_set('runkit.internal_override', '1');
runkit_function_redefine('mail','','return true;');
?>

52. Testing „untestable“ PHP Code

53. Generating testable code
What else?
Remember:
No changes to the source code!

54. Generating testable code
What else?
Generative Programming

55. Generating testable code
Generative Programming
Configuration
Configuration
1 ... n
Implementation
Implementation Generator Product
components Generator Product
components
Generator
Generator
application
application

56. Generating testable code
Generative Programming
Configuration
Configuration
Application
Application
Implementation
Implementation Generator
components Generator
components
Testcases
Testcases
Generator
Generator
application
application

57. Generating testable code
Generative Programming
A frame is a data structure
for representing knowledge.

58. 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()
<?php
function buyCar(Car $oCar) {
global $oDB;
<!{Prefix}!>mysql_query(„INSERT INTO...“, $oDB);
<!{MailSlot}!>
}
?>
ENDCONTENT()
}
}

59. 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()
<?php
function buyCar(Car $oCar) {
global $oDB;
<!{Prefix}!>mysql_query(„INSERT INTO...“, $oDB);
<!{MailSlot}!>
}
?>
ENDCONTENT()
}
}

60. Generating testable code
Generative Programming
Extraction
 Show / hide parts of the code
Example
MailSlot: mail('order@domain.org', 'New sale', '....');

61. Generating testable code
Generative Programming
Extraction
 Show / hide parts of the code
Example
MailSlot: mail('order@domain.org', 'New sale', '....');
<?php
function buyCar(Car $oCar) {
global $oDB;
mysql_query("INSERT INTO...", $oDB);
mail('order@domain.org', 'New sale', '....');
}
?>

62. Generating testable code
Course of action
Customizing
 Change content of global vars
 Pre/Postfixes for own functions, methods, classes
Example
Prefix: test_

63. Generating testable code
Course of action
Customizing
 Change content of global vars
 Pre/Postfixes for own functions, methods, classes
Example
Prefix: test_
<?php
function buyCar(Car $oCar) {
global $oDB;
test_mysql_query("INSERT INTO...", $oDB);
}

64. Conclusion
How much effort to take?

65. Conclusion
Conclusion
Change your mindset to write
testable code!

66. Conclusion
Conclusion
PHP is a swiss army knife.

67. http://joind.in/2420