pear 方式安装：
这种安装方式依靠于PEAR，pear是由php的安装包提供的，并且需要的php版本必须是php 4.3.0以后。
使用这种方式安装phpunit，就得先在本地的Pear环境中注册phpunit依赖的pear （引导）通道，phpunit 主要依赖一下几个通道：
pear channel-discover pear.phpunit.de
pear channel-discover components.ez.no
pear channel-discover pear.symfony-project.com
注册完成以上的通道后就可以用一下的命令安装phpunit到你的php环境中了：）
pear install phpunit/PHPUnit
如果遇到不能安装的情况，可以尝试更新pear的版本等，使用的命令是：pear upgrade-all
手工安装：
Although using the PEAR Installer is the only supported way to install PHPUnit, you can install PHPUnit manually. For manual installation, do the following:
1.Download a release archive from http://pear.phpunit.de/get/ and extract it to a directory that is listed in the include_path of your php.ini configuration file.
2.Prepare the phpunit script:
a）、Rename the phpunit.php script to phpunit.
b）、Replace the @php_bin@ string in it with the path to your PHP command-line interpreter (usually /usr/bin/php).
c）、Copy it to a directory that is in your path and make it executable (chmod +x phpunit).
3.Prepare the PHPUnit/Util/PHP.php script:
a）、Replace the @php_bin@ string in it with the path to your PHP command-line interpreter (usually /usr/bin/php).