public function testAddCustomChannelField()
{
$feed = $this->manager->get('article');
$feed->add(new FakeItemInterfaceEntity());
$feed->addChannelField(new ChannelField('fake_channel_custom', 'My fake value'));
$output = $feed->render('atom');
$this->assertContains('<fake_channel_custom>My fake value</fake_channel_custom>', $output);
}