tests: task has no realistic integration test

[jacquerie]

We are currently only unit testing the task, but we are not testing it a realistic environment, such as a real RabbitMQ instance using the MessagePack protocol. This could be hiding bugs, especially when sending emails with attachments:

invenio-mail/tests/test_invenio_mail_tasks.py

Lines 75 to 114 in 7a44592

	def test_send_message_with_attachments(email_task_app):
	"""Test sending a message with attachments."""
	with email_task_app.app_context():
	filename = pkg_resources.resource_filename(
	__name__, os.path.join('attachments', 'invenio.svg'))
	content_type = 'image/svg+xml'
	data = pkg_resources.resource_string(
	__name__, os.path.join('attachments', 'invenio.svg'))
	attachments = [Attachment(filename, content_type, data)]
	msg = {
	'subject': 'Test3',
	'sender': '[email protected]',
	'recipients': ['[email protected]'],
	'attachments': attachments
	}
	send_email.delay(msg)
	result_stream = email_task_app.extensions['invenio-mail'].stream
	assert result_stream.getvalue().find(
	'Content-Transfer-Encoding: base64') != -1
	assert result_stream.getvalue().find(
	'Content-Disposition: attachment;') != -1
	def test_send_message_with_date(email_task_app):
	"""Test sending a message with a date."""
	with email_task_app.app_context():
	msg = {
	'subject': 'Test4',
	'sender': '[email protected]',
	'recipients': ['[email protected]'],
	'date': 1456242014.398119
	}
	send_email.delay(msg)
	result_stream = email_task_app.extensions['invenio-mail'].stream
	assert result_stream.getvalue().find('Date: Tue, 23 Feb 2016') != -1

.

See #9 (comment) for more details.