How to use the sparkpost.django.exceptions.UnsupportedContent function in sparkpost

def test_unsupported_content_types():
    params = get_params()

    with pytest.raises(UnsupportedContent):
        mail = EmailMultiAlternatives(
            params['subject'],
            'plain text',
            params['from_email'],
            params['recipient_list'])
        mail.attach_alternative('non-plain content', 'text/alien')
        mail.send()

if message.cc:
            formatted['cc'] = message.cc

        if message.bcc:
            formatted['bcc'] = message.bcc

        if hasattr(message, 'reply_to') and message.reply_to:
            formatted['reply_to'] = ','.join(message.reply_to)

        if isinstance(message, EmailMultiAlternatives):
            for alternative in message.alternatives:
                if alternative[1] == 'text/html':
                    formatted['html'] = alternative[0]
                else:
                    raise UnsupportedContent(
                        'Content type %s is not supported' % alternative[1]
                    )

        if message.attachments:
            formatted['attachments'] = []
            str_encoding = settings.DEFAULT_CHARSET
            for attachment in message.attachments:
                filename, content, mimetype = attachment

                if mimetype is None:
                    mimetype, _ = mimetypes.guess_type(filename)
                    if mimetype is None:
                        mimetype = DEFAULT_ATTACHMENT_MIME_TYPE

                try:
                    if isinstance(content, unicode):