Phpunit Error : No Available Commands

I used PEAR to install PHPUnit and had no problems. I'm on a Mac. I used PHPUnit for months without error. Now I haven't used it in a several months, and I ran the same command I ran months ago, but now I get an error. E.g.

$ /opt/local/bin/PHPUnit ActivityUtilTest
No available commands.
Please define them under the following directory:

// -----------------------------
// HERE's the file ActivityUtilTest.php :
// -----------------------------

require_once('bootstrap.php');

class ActivityUtilTest extends PHPUnit_Framework_TestCase {
    public function test01() {
             $this->assertEquals(1, 1);
   }
}

// -----------------------------
// HERE's the file bootstrap.php
// -----------------------------
$yii=dirname(__FILE__).'/../_shared/yii/framework/yii.php';
$config=dirname(__FILE__).'/../_config/CONFIG.php';
require_once($yii);
Yii::createConsoleApplication($config)->run();

I'm running the latest Yii code, version 1.1.12

Any help appreciated, thank you.