Testing PHP/Web Applications with PHPUnit and Selenium

Welcome!
Testing PHP/Web Applications
with PHPUnit 3 and Selenium
Sebastian Bergmann
http://sebastian-bergmann.de/
May 16 th 2007

Who I Am
Sebastian Bergmann
29 years old
Contributor to the PHP Project since 2000
Creator of PHPUnit
Author, Consultant, Trainer
Developer for eZ Systems AS

Who Are You?
Your Background
PHP 5?
OOP?
Testing?
PHPUnit?
Selenium?

The Need for Testing
PHP has evolved from a niche language for small websites to a powerful tool making strong inroads into large-scale, business-critical Web-based systems.
For instance, financial institutions use PHP to develop and maintain solutions for Basel II Credit Rating.
Critical business logic like this needs to work correctly.
But how do you ensure that it does?
You test it, of course!

What Needs Testing?
Web Application
Backend
Business Logic
Reusable Components
Frontend
Form Processing and Template Rendering
Rich Interfaces with AJAX, JSON, ...
Feeds, Web Services, ...

And How Do We Test It?
Web Application
Backend
Functional Testing of Business Logic with Unit Tests
Reusable Components
Third-Party components hopefully come with their own tests
Frontend
Testing with Acceptance Tests or System Tests that “run in the browser”
Testing of Feeds, Web Services, etc. with Unit Tests
Compatibility Testing for Browser / OS combinations
Performance Testing and Security Testing

Testing Software Systems
Unit Testing
Runnable code fragments, so-called Unit Tests , test the correctness of parts, units , of the software.
System Testing
Conducted on a complete, integrated system to evaluate the system's compliance with its specified requirements (from Wikipedia).
Non-Functional Testing
Performance, Stability, Security, Usability, ...

Testing Software Systems
Developer Tests
Ensure that the code works correctly.
Acceptance Tests
Ensure that the code does what the customer wants.

Tool Support for Testing
To make (code) testing viable, good tool support is needed.
This is where a testing framework such as PHPUnit comes into play.
Requirements
Reusable test environment
Strict separation of production code and test code
Automatic execution of test code
Analysis of the result
Easy to learn to use and easy to use

Tools for PHP (and Web) Testing
Unit Testing
PHPUnit
SimpleTest
System Testing
Selenium
PHPUnit + Selenium
Non-Functional Testing
Perfomance, Load, Stress, Reliability, Availability
ab, httperf, JMeter, Grinder, OpenSTA, ...
Security
Chorizo
PHPUnit + Chorizo

Gateway Drug to Test Infection <?php class Calculator { public function add ( $a , $b ) { return $a + $b ; } } ?>

Gateway Drug to Test Infection <?php class Calculator { /** * @assert (0,0) == 0 * @assert (0,1) == 1 * @assert (1,0) == 1 * @assert (1,1) == 2 * @assert (1,2) != 3 */ public function add ( $a , $b ) { return $a + $b ; } } ?>

Gateway Drug to Test Infection

Back to the Beginning
We just used PHPUnit's Skeleton Generator to automatically (generate and) run tests from source code annotations.
While this is handy for simple test cases such as the ones in the previous example, it does not cater well to more complex test scenarios.
So let us take a step back and start from the beginning ...

Writing a Test Case <?php require_once 'PHPUnit/Framework.php' ; require_once 'Calculator.php' ; class CalculatorTest extends PHPUnit_Framework_TestCase { public function testAdd () { $calculator = new Calculator ; $this -> assertEquals ( 0 , $calculator -> add ( 0 , 0 )); $this -> assertEquals ( 1 , $calculator -> add ( 0 , 1 )); $this -> assertEquals ( 1 , $calculator -> add ( 1 , 0 )); $this -> assertEquals ( 2 , $calculator -> add ( 1 , 1 )); $this -> assertNotEquals ( 3 , $calculator -> add ( 1 , 2 )); } } ?>

Running a Test Case

Writing a Test Case <?php require_once 'PHPUnit/Framework.php' ; require_once 'Calculator.php' ; class CalculatorTest extends PHPUnit_Framework_TestCase { protected $calculator ; protected function setUp () { $this -> calculator = new Calculator ; } public function testAdd () { $this -> assertEquals ( 0 , $this -> calculator -> add ( 0 , 0 )); } // ... ?>

Running a Test Case

Organizing Tests into Suites
Application/
Package/
Class (Application/Package/Class.php)
...
...
Tests/
AllTests.php
Package/
AllTests.php
ClassTest (Application/Tests/Package/ClassTest.php)

Organizing Tests into Suites <?php require_once 'PHPUnit/Framework.php' ; require_once 'Application/Tests/Package/AllTests.php' ; class AllTests { public static function suite () { $suite = new PHPUnit_Framework_TestSuite ( 'Project' ); $suite -> addTest ( Package_AllTests :: suite ()); return $suite ; } } ?>

Organizing Tests into Suites <?php require_once 'PHPUnit/Framework.php' ; require_once 'Application/Tests/Package/ClassTest.php' ; class Package_AllTests { public static function suite () { $suite = new PHPUnit_Framework_TestSuite ( 'Package' ); $suite -> addTestSuite ( 'Package_ClassTest' ); return $suite ; } } ?>

Testing Practices
You can always write more tests.
However, you will quickly find that only a fraction of the tests you can imagine are actually useful.
What you want is to write tests that fail even though you think they should work, or tests that succeed even though you think they should fail.
Another way to think of it is in cost / benefit terms.
You want to write tests that will pay you back with information.
This slide contains material by Erich Gamma.

Testing Practices
During Development
A test suite is invaluable while refactoring.
During Debugging
Verify that you can reproduce the defect.
Find the smallest-scale demonstration of the defect in the code.
Write an automated test that fails now but will succeed when the defect is fixed.
Fix the defect.

Test-Driven Development
Tests drive the development.
Tests written before code.
No code without tests.
This slide contains material by Brady Kelly.
Method of designing software, not just a method of testing software.
Test
What do we want X to do?
How do we want to tell X to do it?
How will we know when X has done it?
Code
How does X do it?

Test-Driven Development The BankAccount Example
Let's implement a class that represents a bank account using TDD.
API
Retrieve the current balance.
Set the balance.
Deposit money.
Withdraw money.
Rules
Balance is initially zero.
Balance cannot become negative.

Test-Driven Development The BankAccount Example <?php require_once 'PHPUnit/Framework.php' ; require_once 'BankAccount.php' ; class BankAccountTest extends PHPUnit_Framework_TestCase { private $ba ; protected function setUp () { $this -> ba = new BankAccount ; } public function testBalanceIsInitiallyZero () { $this -> assertEquals ( 0 , $this -> ba -> getBalance ()); } } ?>

Test-Driven Development The BankAccount Example <?php require_once 'PHPUnit/Framework.php' ; require_once 'BankAccount.php' ; class BankAccountTest extends PHPUnit_Framework_TestCase { // ... public function testBalanceCannotBecomeNegative () { try { $this -> ba -> withdrawMoney ( 1 ); } catch ( BankAccountException $e ) { return; } $this -> fail (); } } ?>

Test-Driven Development The BankAccount Example <?php require_once 'PHPUnit/Framework.php' ; require_once 'BankAccount.php' ; class BankAccountTest extends PHPUnit_Framework_TestCase { // ... public function testBalanceCannotBecomeNegative2 () { try { $this -> ba -> depositMoney (- 1 ); } catch ( BankAccountException $e ) { return; } $this -> fail (); } } ?>

Test-Driven Development The BankAccount Example <?php require_once 'PHPUnit/Framework.php' ; require_once 'BankAccount.php' ; class BankAccountTest extends PHPUnit_Framework_TestCase { // ... public function testBalanceCannotBecomeNegative3 () { try { $this -> ba -> setBalance (- 1 ); } catch ( BankAccountException $e ) { return; } $this -> fail (); } } ?>

Test-Driven Development The BankAccount Example <?php require_once 'BankAccountException.php' ; class BankAccount { private $balance = 0 ; public function getBalance () { return $this -> balance ; } public function setBalance ( $balance ) { if ( $balance >= 0 ) { $this -> balance = $balance ; } else { throw new BankAccountException ; } } } ?>

Test-Driven Development The BankAccount Example <?php require_once 'BankAccountException.php' ; class BankAccount { // ... public function depositMoney ( $balance ) { $this -> setBalance ( $this -> getBalance () + $balance ); return $this -> getBalance (); } public function withdrawMoney ( $balance ) { $this -> setBalance ( $this -> getBalance () - $balance ); return $this -> getBalance (); } } ?>

Test-Driven Development The BankAccount Example

Code Coverage The BankAccount Example

Test-Driven Development The BankAccount Example <?php require_once 'PHPUnit/Framework.php' ; require_once 'BankAccount.php' ; class BankAccountTest extends PHPUnit_Framework_TestCase { // ... public function testDepositWithdrawMoney () { $this -> assertEquals ( 0 , $this -> ba -> getBalance ()); $this -> ba -> depositMoney ( 1 ); $this -> assertEquals ( 1 , $this -> ba -> getBalance ()); $this -> ba -> withdrawMoney ( 1 ); $this -> assertEquals ( 0 , $this -> ba -> getBalance ()); } } ?>

Code Coverage The BankAccount Example

Test-Driven Development
Microsoft Case Study
TDD project had twice the code quality.
Writing the tests required 15% more time.
IBM Case Study
40% fewer defects.
No impact on the team's productivity.
John Deere / Ericsson Case Study
TDD produces higher quality code.
Impact of 16% on the team's productivity.
But the comparison team did not test at all.

The Testivus Manifestivus
Less testing dogma, more testing karma.
Any tests are better than no tests.
Testing beats debugging.
Test first, during, or after – whatever works best for you.
If a method, technique, or tool gives you more or better tests, use it.
Alberto Savoia on DeveloperTesting.com

PHPUnit Features
Test Framework
Member of the xUnit family of test frameworks
Mock Objects
Integration
Selenium RC
CruiseControl
Even More Cool Stuff :-)
Code Coverage
Test Database
Mutation Testing (GSoC07 project)

Selenium
Selenium
Test tool for web applications
Browser Compatibility Testing
System Functional Testing
Runs in the browser
Selenium IDE
IDE for Selenium tests
Record, edit, debug tests in the browser

Selenium
Selenium RC
Automated execution of Selenium tests
Tests can be specified in any programming language
PHP bindings exist
PHPUnit can talk to a Selenium RC server directly
With the right setup, a test can be tested in different browsers on different operating systems

Selenium RC

The End
Thank you for your interest!
These slides will be available shortly on http://sebastian-bergmann.de/talks/.

Bibliography
T. Bhat, N. Nagappan, “Evaluating the Efficacy of Test-Driven Development: Industrial Case Studies”, ISESE'06, September 21–22, 2006, Rio de Janeiro, Brazil.
L. Williams, E. M. Maximilien, and M. Vouk, “Test-Driven Development as a Defect-Reduction Practice”, Proceedings of IEEE International Symposium on Software Reliability Engineering, Denver, CO, pp. 34-45, 2003.
B. George and L. Williams, “A Structured Experiment of Test-Driven Development”, Information and Software Technology (IST), 46(5), pp. 337-342, 2003.

License
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Attribution. You must attribute the work in the manner specified by the author or licensor (but not in any way that suggests that they endorse you or your use of the work).
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No Derivative Works. You may not alter, transform, or build upon this work.
For any reuse or distribution, you must make clear to others the license terms of this work. The best way to do this is with a link to this web page.
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Testing PHP/Web Applications with PHPUnit and Selenium

by Sebastian Bergmann on May 16, 2007

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Testing PHP/Web Applications with PHPUnit and Selenium — Presentation Transcript