CsvEncoder class seems to not consider context.
This leads to "circular reference" error on encoding since Groups Annotaton are not processed.

Example:

$serializer = new Serializer([new ObjectNormalizer()], [new CsvEncoder()]);
$data = $serializer->encode($items, 'csv', array('groups' => array('export')));

The entitiy has only one field with the annotation "groups":

/**
 * @var string
 *
 * @ORM\Column(name="title", type="string", length=255)
 * @Groups({"export"})
 * @Assert\NotNull()  
 */
private $title;

As far as I can see, the CsvEncoder Class Symfony\Component\Serializer\Encoder\CsvEncoder does not consider the $context at all.

Even though the method public function encode($data, $format, array $context = array()) defines it, $context is nowhere used in the method.