首先确保你的代码像这样：

<?php
class TestTest extends PHPUnit_Framework_TestCase{   

/**     
* @group a     
*/   

public function testOne()   
{   
}     

/**     
* @group a     
* @group b     
*/   

public function testTwo()   
{   
}

}

?>

 sb@vmware ~ % phpunit --group a TestTest
PHPUnit 3.2.0-dev by Sebastian Bergmann.
Time: 0 seconds
OK (2 tests)

sb@vmware ~ % phpunit --group b TestTest
PHPUnit 3.2.0-dev by Sebastian Bergmann.
Time: 0 seconds
OK (1 test)