Fixed crasher when sending rfc822 messages as attachments. (#59)

tests/test_mailgun_backend.py

@@ -1,6 +1,14 @@
 # -*- coding: utf-8 -*-
 
 from datetime import date, datetime
+try:
+    from email import message_from_bytes
+except ImportError:
+    from email import message_from_string
+
+    def message_from_bytes(s):
+        return message_from_string(s.decode('utf-8'))
+
 from email.mime.base import MIMEBase
 from email.mime.image import MIMEImage
 
@@ -14,7 +22,7 @@ from anymail.exceptions import AnymailAPIError, AnymailRequestsAPIError, Anymail
 from anymail.message import attach_inline_image_file
 
 from .mock_requests_backend import RequestsBackendMockAPITestCase, SessionSharingTestCasesMixin
-from .utils import sample_image_content, sample_image_path, SAMPLE_IMAGE_FILENAME, AnymailTestMixin
+from .utils import sample_image_content, sample_image_path, SAMPLE_FORWARDED_EMAIL, SAMPLE_IMAGE_FILENAME, AnymailTestMixin
 
 
 @override_settings(EMAIL_BACKEND='anymail.backends.mailgun.EmailBackend',
@@ -131,13 +139,27 @@ class MailgunBackendStandardEmailTests(MailgunBackendMockAPITestCase):
         mimeattachment.set_payload(pdf_content)
         self.message.attach(mimeattachment)
 
+        # And also with an message/rfc822 attachment
+        forwarded_email = message_from_bytes(SAMPLE_FORWARDED_EMAIL)
+        rfcmessage = MIMEBase("message", "rfc822")
+        rfcmessage.attach(forwarded_email)
+        self.message.attach(rfcmessage)
+
         self.message.send()
         files = self.get_api_call_files()
         attachments = [value for (field, value) in files if field == 'attachment']
-        self.assertEqual(len(attachments), 3)
+        self.assertEqual(len(attachments), 4)
         self.assertEqual(attachments[0], ('test.txt', text_content, 'text/plain'))
         self.assertEqual(attachments[1], ('test.png', png_content, 'image/png'))  # type inferred from filename
         self.assertEqual(attachments[2], (None, pdf_content, 'application/pdf'))  # no filename
+        # Email messages can get a bit changed with respect to
+        # whitespace characters in headers, without breaking the message, so we
+        # tolerate that:
+        self.assertEqual(attachments[3][0], None)
+        self.assertEqual(attachments[3][1].replace(b'\n', b'').replace(b' ', b''),
+                         (b'Content-Type: message/rfc822\nMIME-Version: 1.0\n\n' + SAMPLE_FORWARDED_EMAIL).replace(b'\n', b'').replace(b' ', b''))
+        self.assertEqual(attachments[3][2], 'message/rfc822')
+
         # Make sure the image attachment is not treated as embedded:
         inlines = [value for (field, value) in files if field == 'inline']
         self.assertEqual(len(inlines), 0)