Handle empty rooms when generating email notifications. (#9257)

Fixes some exceptions if the room state isn't quite as expected.
If the expected state events aren't found, try to find them in the
historical room state. If they still aren't found, fallback to a reasonable,
although ugly, value.

1 files changed, 49 insertions, 2 deletions

diff --git a/tests/push/test_email.py b/tests/push/test_email.py
index c4e1e7ed85..22f452ec24 100644
--- a/tests/push/test_email.py
+++ b/tests/push/test_email.py
@@ -124,13 +124,18 @@ class EmailPusherTests(HomeserverTestCase):
         )
         self.helper.join(room=room, user=self.others[0].id, tok=self.others[0].token)
 
-        # The other user sends some messages
+        # The other user sends a single message.
         self.helper.send(room, body="Hi!", tok=self.others[0].token)
-        self.helper.send(room, body="There!", tok=self.others[0].token)
 
         # We should get emailed about that message
         self._check_for_mail()
 
+        # The other user sends multiple messages.
+        self.helper.send(room, body="Hi!", tok=self.others[0].token)
+        self.helper.send(room, body="There!", tok=self.others[0].token)
+
+        self._check_for_mail()
+
     def test_invite_sends_email(self):
         # Create a room and invite the user to it
         room = self.helper.create_room_as(self.others[0].id, tok=self.others[0].token)
@@ -217,6 +222,45 @@ class EmailPusherTests(HomeserverTestCase):
         # We should get emailed about those messages
         self._check_for_mail()
 
+    def test_empty_room(self):
+        """All users leaving a room shouldn't cause the pusher to break."""
+        # Create a simple room with two users
+        room = self.helper.create_room_as(self.user_id, tok=self.access_token)
+        self.helper.invite(
+            room=room, src=self.user_id, tok=self.access_token, targ=self.others[0].id
+        )
+        self.helper.join(room=room, user=self.others[0].id, tok=self.others[0].token)
+
+        # The other user sends a single message.
+        self.helper.send(room, body="Hi!", tok=self.others[0].token)
+
+        # Leave the room before the message is processed.
+        self.helper.leave(room, self.user_id, tok=self.access_token)
+        self.helper.leave(room, self.others[0].id, tok=self.others[0].token)
+
+        # We should get emailed about that message
+        self._check_for_mail()
+
+    def test_empty_room_multiple_messages(self):
+        """All users leaving a room shouldn't cause the pusher to break."""
+        # Create a simple room with two users
+        room = self.helper.create_room_as(self.user_id, tok=self.access_token)
+        self.helper.invite(
+            room=room, src=self.user_id, tok=self.access_token, targ=self.others[0].id
+        )
+        self.helper.join(room=room, user=self.others[0].id, tok=self.others[0].token)
+
+        # The other user sends a single message.
+        self.helper.send(room, body="Hi!", tok=self.others[0].token)
+        self.helper.send(room, body="There!", tok=self.others[0].token)
+
+        # Leave the room before the message is processed.
+        self.helper.leave(room, self.user_id, tok=self.access_token)
+        self.helper.leave(room, self.others[0].id, tok=self.others[0].token)
+
+        # We should get emailed about that message
+        self._check_for_mail()
+
     def test_encrypted_message(self):
         room = self.helper.create_room_as(self.user_id, tok=self.access_token)
         self.helper.invite(
@@ -269,3 +313,6 @@ class EmailPusherTests(HomeserverTestCase):
         pushers = list(pushers)
         self.assertEqual(len(pushers), 1)
         self.assertTrue(pushers[0].last_stream_ordering > last_stream_ordering)
+
+        # Reset the attempts.
+        self.email_attempts = []