mattermost: Handle duplicate dm-groups.

Observed in the wild, cause unknown.

Partially fixes: zulip#24131.

Co-authored-by: Mateusz Mandera <[email protected]>

Author: 2 people

zerver/data_import/mattermost.py

@@ -244,6 +244,9 @@ def convert_direct_message_group_data(
     for direct_message_group in direct_message_group_data:
         if len(direct_message_group["members"]) > 2:
             direct_message_group_members = frozenset(direct_message_group["members"])
+            if direct_message_group_id_mapper.has(direct_message_group_members):
+                logging.info("Duplicate direct message group found in the export data. Skipping.")
+                continue
             direct_message_group_id = direct_message_group_id_mapper.get(
                 direct_message_group_members
             )

zerver/tests/fixtures/mattermost_fixtures/direct_channel/export.json

@@ -13,6 +13,7 @@
 {"type":"post","post":{"team":"gryffindor","channel":"gryffindor-common-room","user":"harry","message":"Looks like this channel is empty","create_at":1553166567370,"reactions":[{"user":"ron","create_at":1553166584976,"emoji_name":"rocket"}],"replies":null,"attachments":[{"path":"20210622/teams/noteam/channels/mcrm7xee5bnpzn7u9ktsd91dwy/users/knq189b88fdxbdkeeasdynia4o/smaa5epsnp89tgjszzue1691ao/this is a file"}]}}
 {"type":"direct_channel","direct_channel":{"members":["ron","harry"],"favorited_by":null,"header":""}}
 {"type":"direct_channel","direct_channel":{"members":["ron","harry", "ginny"],"favorited_by":null,"header":""}}
+{"type":"direct_channel","direct_channel":{"members":["harry","ron", "ginny"],"favorited_by":null,"header":""}}
 {"type":"direct_post","direct_post":{"channel_members":["ron","harry"],"user":"ron","message":"hey harry","create_at":1566376137676,"flagged_by":null,"reactions":null,"replies":null,"attachments":[{"path":"20210622/teams/noteam/channels/mcrm7xee5bnpzn7u9ktsd91dwy/users/knq189b88fdxbdkeeasdynia4o/o3to4ezua3bajj31mzpkn96n5e/harry-ron.jpg"}]}}
 {"type":"direct_post","direct_post":{"channel_members":["ron","harry"],"user":"harry","message":"what's up","create_at":1566376318568,"flagged_by":null,"reactions":null,"replies":null,"attachments":null}}
 {"type":"direct_post","direct_post":{"channel_members":["ron","harry","ginny"],"user":"ginny","message":"Who is going to Hogsmeade this weekend?","create_at":1566376226493,"flagged_by":null,"reactions":null,"replies":null,"attachments":null}}

zerver/tests/test_mattermost_importer.py

@@ -357,15 +357,16 @@ def test_convert_direct_message_group_data(self) -> None:
             team_name=team_name,
         )
 
-        zerver_huddle = convert_direct_message_group_data(
-            direct_message_group_data=mattermost_data["direct_channel"],
-            user_data_map=username_to_user,
-            subscriber_handler=subscriber_handler,
-            direct_message_group_id_mapper=direct_message_group_id_mapper,
-            user_id_mapper=user_id_mapper,
-            realm_id=3,
-            team_name=team_name,
-        )
+        with self.assertLogs(level="INFO") as mock_log:
+            zerver_huddle = convert_direct_message_group_data(
+                direct_message_group_data=mattermost_data["direct_channel"],
+                user_data_map=username_to_user,
+                subscriber_handler=subscriber_handler,
+                direct_message_group_id_mapper=direct_message_group_id_mapper,
+                user_id_mapper=user_id_mapper,
+                realm_id=3,
+                team_name=team_name,
+            )
 
         self.assert_length(zerver_huddle, 1)
         direct_message_group_members = frozenset(mattermost_data["direct_channel"][1]["members"])
@@ -379,6 +380,10 @@ def test_convert_direct_message_group_data(self) -> None:
             ),
             {1, 2, 3},
         )
+        self.assertEqual(
+            mock_log.output,
+            ["INFO:root:Duplicate direct message group found in the export data. Skipping."],
+        )
 
     def test_write_emoticon_data(self) -> None:
         fixture_file_name = self.fixture_file_name("export.json", "mattermost_fixtures")