[tests] add test to validate signature from apple mail

This change adds test to validate signature of encrypted email created
by apple mail. It's important to note that apple mail has a specific way
to encrypt signed messages. First it sign the email and then encrypt the
previous signed message. It was also added a message file with the
expected data.

1 files changed, 8 insertions, 4 deletions

diff --git a/src/leap/mail/incoming/service.py b/src/leap/mail/incoming/service.py
index f60921a..bf850b5 100644
--- a/src/leap/mail/incoming/service.py
+++ b/src/leap/mail/incoming/service.py
@@ -458,10 +458,8 @@ class IncomingMail(Service):
                     self.LEAP_SIGNATURE_HEADER,
                     self.LEAP_SIGNATURE_INVALID)
             else:
-                decrmsg.add_header(
-                    self.LEAP_SIGNATURE_HEADER,
-                    self.LEAP_SIGNATURE_VALID,
-                    pubkey=signkey.fingerprint)
+                self._add_verified_signature_header(decrmsg,
+                                                    signkey.fingerprint)
             return decrmsg.as_string()
 
         if msg.get_content_type() == MULTIPART_ENCRYPTED:
@@ -475,6 +473,12 @@ class IncomingMail(Service):
         d.addCallback(add_leap_header)
         return d
 
+    def _add_verified_signature_header(self, decrmsg, fingerprint):
+        decrmsg.add_header(
+            self.LEAP_SIGNATURE_HEADER,
+            self.LEAP_SIGNATURE_VALID,
+            pubkey=fingerprint)
+
     def _add_decrypted_header(self, msg):
         msg.add_header(self.LEAP_ENCRYPTION_HEADER,
                        self.LEAP_ENCRYPTION_DECRYPTED)