Testing that the package works - install it
The best way to test that your meta package works is to uninstall at least one of the packages that is a dependency of it, then [re]install your meta package.
$ pear uninstall PHP_CodeSniffer $ pear install -f package.xml
Installing the meta package here should result in the dependency, PHP_CodeSniffer, being installed also.
Check this using pear list.
$ pear list