title: Run multiple test suites with PHPUnit
body: <p>In my <code>phpunit.xml</code> I have a number of <code>&lt;testsuite&gt;</code>'s defined each of which defines a different aspect of my application to test. During development I don't want to necessarily run every test suite, only the ones in the aspect I'm working on.</p>
  
  <p>However, when I want to test my full application I'd like to specify multiple test suites to run. Is there a way to do this from the command line?</p>