Testing if mail headers are properly removed

ZendMailTest.php

<?php
namespace BMytest;

class ZendMailTest extends \PHPUnit_Framework_TestCase
{
    public function testRemovingHeadersFromMultipleMailObjects()
    {
        $mail1 = new \Zend_Mail();
        $mail1->addHeader('foo', 'bar');
        $mail1->addHeader('x-mfo-mailid', uniqid());

        $mail2 = clone $mail1;
        $mail2->addHeader('bar', 'baz', true);

        $mail3 = clone $mail2;
        $mail3->addHeader('baz', 'foobar', true);
        $mailList = array ($mail1, $mail2, $mail3);

        foreach ($mailList as $mail) {
            $mail->clearHeader('x-mfo-mailid');
            $this->assertArrayNotHasKey('x-mfo-mailid', $mail->getHeaders());
        }
    }
}