什么是PHPUnit？
PHPUnit是一个轻量级的PHP测试框架。它是在PHP5下面对JUnit3系列版本的完整移植，是xUnit测试框架家族的一员(它们都基于模式先锋Kent Beck的设计)
Ubuntu上安装
sudo apt-get install phpunit
验证PHPUnit安装成功，命令行输入phpunit
$ phpunit
安装成功打印：
PHPUnit 3.6.11 by Sebastian Bergmann.
Usage: phpunit [switches] UnitTest [UnitTest.php]
phpunit [switches] <directory>
如果出现如下的错误。
PHP Warning: require_once(PHP/CodeCoverage/Filter.php): failed to open stream: No such file or directory in /usr/bin/phpunit on line 39
PHP Fatal error: require_once(): Failed opening required 'PHP/CodeCoverage/Filter.php' (include_path='.:/usr/share/php:/usr/share/pear') in /usr/bin/phpunit on line 39
更新 chanel 和 pear，来自 Debian 和 ubuntu 社区的方法。测试可用
sudo apt-get remove phpunit
sudo pear channel-discover pear.phpunit.de
sudo pear channel-discover pear.symfony-project.com
sudo pear channel-discover components.ez.no
sudo pear update-channels
sudo pear upgrade-all
sudo pear install --alldeps phpunit/PHPUnit
