def METHOD_NAME(self):
    attach = BytesIO()
    attach.write(b"content")
    attach.seek(0)
    attachs = [("attachment", "text/plain", attach)]
    mailsender = MailSender(debug=True)
    mailsender.send(
        to=["test@scrapy.org"],
        subject="subject",
        body="body",
        attachs=attachs,
        _callback=self._catch_mail_sent,
    )
    assert self.catched_msg
    self.assertEqual(self.catched_msg["to"], ["test@scrapy.org"])
    self.assertEqual(self.catched_msg["subject"], "subject")
    self.assertEqual(self.catched_msg["body"], "body")
    msg = self.catched_msg["msg"]
    self.assertEqual(msg["to"], "test@scrapy.org")
    self.assertEqual(msg["subject"], "subject")
    payload = msg.get_payload()
    assert isinstance(payload, list)
    self.assertEqual(len(payload), 2)
    text, attach = payload
    self.assertEqual(text.get_payload(decode=True), b"body")
    self.assertEqual(text.get_charset(), Charset("us-ascii"))
    self.assertEqual(attach.get_payload(decode=True), b"content")