State of PHP QA Tools
Sebastian Bergmann
June 25th 2009

Who I Am
 Sebastian Bergmann
 Involved in the PHP
project since 2000
 Creator of PHPUnit
 Co-Founder and
Principal Consultant
with thePHP.cc
 Developer with
eZ Systems

When things go wrong ...

Why did I not
test this?

 Does my code work?
 Be confident in your code!
 Do not be afraid of changing your code!

Does my code work?
Classic Approach
 Write a test program
 Run the test program
 Manually verify the output
 Delete the test program

Does my code work?
Agile Approach
Write a unit test
 Automatic evaluation of the test result
 Instant feedback
 Simple test environment
 Allows for the earliest possible testing of a
code unit
 Executable specification
 Is not deleted but kept as regression test

Unit Tests improve the confidence in your code
as they detect problems as early as possible

Show
Me
The
Code!

How do we measure
Software Quality?

Software Metrics
 A software metric is a measure of some
property of a piece of software or its
specifications.
 „You cannot control what you cannot
measure.“ (Tom DeMarco)

Software Metrics
Code Coverage
 Which statements, branches, and paths
are executed when the tests run?
 Statement Coverage
 Branch Coverage
 Path Coverage
 100% Code Coverage is a required, but
not a sufficient criteria for test
completeness

Software Metrics
Lines of Code
 Text-based metric for code size
 Various definitions
 Lines of Code (LOC)
 Comment Lines of Code (CLOC)
 Non-Comment Lines of Code (NCLOC)
 Executable Lines of Code (ELOC)
 Ratios can be interesting
 CLOC / (E)LOC

Software Metrics
Lines of Code
sb@thinkpad ~ % pear install phpunit/phploc
downloading phploc-1.0.0.tgz ...
Starting to download phploc-1.0.0.tgz (5,834 bytes)
.....done: 5,834 bytes
install ok: channel://pear.phpunit.de/phploc-1.0.0
sb@thinkpad ~ % phploc /usr/local/src/ezcomponents/trunk/Workflow
phploc 1.0.0 by Sebastian Bergmann.
Directories: 13
Files: 102
Lines of Code (LOC): 14066
Executable Lines of Code (ELOC): 5710
Comment Lines of Code (CLOC): 5228
Non-Comment Lines of Code (NCLOC): 8838
Interfaces: 7
Classes: 90
Functions/Methods: 566

Software Metrics
Code Duplication
 Two sequences of code are duplicate
when they are
 textually identical
 token for token identical
 functionally identical
 Problems
 Duplicate code contradicts code reuse
 Co-Evolution of clones hinders maintenance

Software Metrics
Code Duplication
sb@thinkpad ~ % pear install phpunit/phpcpd
downloading phpcpd-1.1.0.tgz ...
Starting to download phpcpd-1.1.0.tgz (8,226 bytes)
.....done: 8,226 bytes
install ok: channel://pear.phpunit.de/phpcpd-1.1.0
sb@thinkpad ~ % phpcpd /usr/local/src/phpunit/trunk/PHPUnit
phpcpd 1.1.0 by Sebastian Bergmann.
Found 4 exact clones with 131 duplicated lines in 7 files:
- Extensions/Database/DataSet/AbstractTable.php:156-190
Extensions/Database/DataSet/ReplacementTable.php:172-206
- Samples/BankAccountDB/BankAccountDBTest.php:84-128
Samples/BankAccountDB/BankAccountDBTestMySQL.php:84-128
- Tests/Extensions/Database/DataSet/XmlDataSetsTest.php:71-98
Tests/Extensions/Database/DataSet/YamlDataSetTest.php:70-97
- Tests/Extensions/Database/DataSet/XmlDataSetsTest.php:71-97
Tests/Extensions/Database/DataSet/CsvDataSetTest.php:70-96
0.21% duplicated lines out of 61720 total lines of code.

Software Metrics
Cyclomatic Complexity
 Measures the complexity of a code unit
 Originally defined in graph theory
ccn(G) = Edges - Vertices + 2
 Equivalent: Counting the branching points
if, for, foreach, while, case, catch, &&, ||,
ternary operator (?:)
 Interpretation
 Higher complexity leads to more errors
 Higher complexity makes testing harder

Software Metrics
Cyclomatic Complexity
<?php
1 function isLeapYear($year)
{
$result = false;
2 if ($year % 4 != 0) {
$result = false;
}
3 if ($year % 100 != 0) {
$result = true;
}
4 if ($year % 400 == 0) {
$result = true;
}
return $result;
}

Software Metrics
pdepend
 Static Analysis of PHP Code
 Software Metrics
 Software Visualization
 Helps to identify parts of an application
that should be refactored
sb@thinkpad ~ % pear channel-discover pear.pdepend.org
Adding Channel "pear.pdepend.org" succeeded
Discovery of channel "pear.pdepend.org" succeeded
sb@thinkpad ~ % pear install pdepend/PHP_Depend
downloading PHP_Depend-0.9.4.tgz ...
Starting to download PHP_Depend-0.9.4.tgz (161,553 bytes)
..................................done: 161,553 bytes
install ok: channel://pear.pdepend.org/PHP_Depend-0.9.4

Software Metrics
phpmd
 Static Analysis of PHP Code
 Based on PHP_Depend
 Reports violations of rules that operate on
raw software metrics data

Software Metrics
phpcs
 Static Analysis of PHP Code
 Based on ext/tokenizer
 ”Sniffs”
 Coding Standard
 Software Metrics
 Bug Patterns
 Performance Patterns
 ...

QA Tools for PHP
 phpunit → JUnit XML and Clover XML
 phpcs → Checkstyle XML
 pdepend → JDepend XML
 phpmd → PMD XML
 phpcpd → PMD-CPD XML

The End
Thank you for your interest!
These slides will be posted on
http://www.slideshare.net/sebastian_bergmann

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