The only requirement is the SMSGlobal REST API Client for PHP 5.2. There is a git submodule for it; otherwise you can get it directly from GitHub. Install it to the vendor/rest-api-client-php-5.2 directory.
With version 1.6.5 of git and later, you can use:
git clone --recursive git://github.com/smsglobal/smsglobal-wordpress-plugin smsglobal
For older versions, use:
git clone git://github.com/smsglobal/smsglobal-wordpress-plugin smsglobal
cd smsglobal
git submodule init
git submodule update
Done via PHPUnit. The test shell script will do initial setup and testing:
$ ./test
After the first run, you can use PHPUnit as normal:
$ phpunit