in page 49 of this book i have a problem with understanding that why we should use this line to call the class ?!
$message = new MessageController('messageTest');
in this function :
public function testRepeat()
{
$message = new MessageController('messageTest');
$yell = "Hello, Any One Out There?";
$returnedMessage = $message->repeat($yell);
$this->assertEquals($returnedMessage, $yell);
}
why should use the ‘messageTest’ ?
what is this?!? 
sorry for my bad English …