Improve and refactor the tests for relations. (#12113)

* Modernizes code (f-strings, etc.)
* Fixes incorrect comments.
* Splits the test case into two.
* Factors out some duplicated code.

2 files changed, 179 insertions, 208 deletions

diff --git a/changelog.d/12113.misc b/changelog.d/12113.misc
new file mode 100644
index 0000000000..102e064053
--- /dev/null
+++ b/changelog.d/12113.misc
@@ -0,0 +1 @@
+Refactor the tests for event relations.
diff --git a/tests/rest/client/test_relations.py b/tests/rest/client/test_relations.py
index c8db45719e..a087cd7b21 100644
--- a/tests/rest/client/test_relations.py
+++ b/tests/rest/client/test_relations.py
@@ -34,7 +34,7 @@ from tests.test_utils import make_awaitable
 from tests.test_utils.event_injection import inject_event
 
 
-class RelationsTestCase(unittest.HomeserverTestCase):
+class BaseRelationsTestCase(unittest.HomeserverTestCase):
     servlets = [
         relations.register_servlets,
         room.register_servlets,
@@ -48,7 +48,6 @@ class RelationsTestCase(unittest.HomeserverTestCase):
     def default_config(self) -> dict:
         # We need to enable msc1849 support for aggregations
         config = super().default_config()
-        config["experimental_msc1849_support_enabled"] = True
 
         # We enable frozen dicts as relations/edits change event contents, so we
         # want to test that we don't modify the events in the caches.
@@ -67,10 +66,62 @@ class RelationsTestCase(unittest.HomeserverTestCase):
         res = self.helper.send(self.room, body="Hi!", tok=self.user_token)
         self.parent_id = res["event_id"]
 
-    def test_send_relation(self) -> None:
-        """Tests that sending a relation using the new /send_relation works
-        creates the right shape of event.
+    def _create_user(self, localpart: str) -> Tuple[str, str]:
+        user_id = self.register_user(localpart, "abc123")
+        access_token = self.login(localpart, "abc123")
+
+        return user_id, access_token
+
+    def _send_relation(
+        self,
+        relation_type: str,
+        event_type: str,
+        key: Optional[str] = None,
+        content: Optional[dict] = None,
+        access_token: Optional[str] = None,
+        parent_id: Optional[str] = None,
+    ) -> FakeChannel:
+        """Helper function to send a relation pointing at `self.parent_id`
+
+        Args:
+            relation_type: One of `RelationTypes`
+            event_type: The type of the event to create
+            key: The aggregation key used for m.annotation relation type.
+            content: The content of the created event. Will be modified to configure
+                the m.relates_to key based on the other provided parameters.
+            access_token: The access token used to send the relation, defaults
+                to `self.user_token`
+            parent_id: The event_id this relation relates to. If None, then self.parent_id
+
+        Returns:
+            FakeChannel
         """
+        if not access_token:
+            access_token = self.user_token
+
+        original_id = parent_id if parent_id else self.parent_id
+
+        if content is None:
+            content = {}
+        content["m.relates_to"] = {
+            "event_id": original_id,
+            "rel_type": relation_type,
+        }
+        if key is not None:
+            content["m.relates_to"]["key"] = key
+
+        channel = self.make_request(
+            "POST",
+            f"/_matrix/client/v3/rooms/{self.room}/send/{event_type}",
+            content,
+            access_token=access_token,
+        )
+        return channel
+
+
+class RelationsTestCase(BaseRelationsTestCase):
+    def test_send_relation(self) -> None:
+        """Tests that sending a relation works."""
 
         channel = self._send_relation(RelationTypes.ANNOTATION, "m.reaction", key="👍")
         self.assertEqual(200, channel.code, channel.json_body)
@@ -79,7 +130,7 @@ class RelationsTestCase(unittest.HomeserverTestCase):
 
         channel = self.make_request(
             "GET",
-            "/rooms/%s/event/%s" % (self.room, event_id),
+            f"/rooms/{self.room}/event/{event_id}",
             access_token=self.user_token,
         )
         self.assertEqual(200, channel.code, channel.json_body)
@@ -317,9 +368,7 @@ class RelationsTestCase(unittest.HomeserverTestCase):
 
         # Request /sync, limiting it such that only the latest event is returned
         # (and not the relation).
-        filter = urllib.parse.quote_plus(
-            '{"room": {"timeline": {"limit": 1}}}'.encode()
-        )
+        filter = urllib.parse.quote_plus(b'{"room": {"timeline": {"limit": 1}}}')
         channel = self.make_request(
             "GET", f"/sync?filter={filter}", access_token=self.user_token
         )
@@ -404,8 +453,7 @@ class RelationsTestCase(unittest.HomeserverTestCase):
 
             channel = self.make_request(
                 "GET",
-                "/_matrix/client/unstable/rooms/%s/aggregations/%s?limit=1%s"
-                % (self.room, self.parent_id, from_token),
+                f"/_matrix/client/unstable/rooms/{self.room}/aggregations/{self.parent_id}?limit=1{from_token}",
                 access_token=self.user_token,
             )
             self.assertEqual(200, channel.code, channel.json_body)
@@ -544,8 +592,7 @@ class RelationsTestCase(unittest.HomeserverTestCase):
 
         channel = self.make_request(
             "GET",
-            "/_matrix/client/unstable/rooms/%s/aggregations/%s"
-            % (self.room, self.parent_id),
+            f"/_matrix/client/unstable/rooms/{self.room}/aggregations/{self.parent_id}",
             access_token=self.user_token,
         )
         self.assertEqual(200, channel.code, channel.json_body)
@@ -560,47 +607,13 @@ class RelationsTestCase(unittest.HomeserverTestCase):
             },
         )
 
-    def test_aggregation_redactions(self) -> None:
-        """Test that annotations get correctly aggregated after a redaction."""
-
-        channel = self._send_relation(RelationTypes.ANNOTATION, "m.reaction", "a")
-        self.assertEqual(200, channel.code, channel.json_body)
-        to_redact_event_id = channel.json_body["event_id"]
-
-        channel = self._send_relation(
-            RelationTypes.ANNOTATION, "m.reaction", "a", access_token=self.user2_token
-        )
-        self.assertEqual(200, channel.code, channel.json_body)
-
-        # Now lets redact one of the 'a' reactions
-        channel = self.make_request(
-            "POST",
-            "/_matrix/client/r0/rooms/%s/redact/%s" % (self.room, to_redact_event_id),
-            access_token=self.user_token,
-            content={},
-        )
-        self.assertEqual(200, channel.code, channel.json_body)
-
-        channel = self.make_request(
-            "GET",
-            "/_matrix/client/unstable/rooms/%s/aggregations/%s"
-            % (self.room, self.parent_id),
-            access_token=self.user_token,
-        )
-        self.assertEqual(200, channel.code, channel.json_body)
-
-        self.assertEqual(
-            channel.json_body,
-            {"chunk": [{"type": "m.reaction", "key": "a", "count": 1}]},
-        )
-
     def test_aggregation_must_be_annotation(self) -> None:
         """Test that aggregations must be annotations."""
 
         channel = self.make_request(
             "GET",
-            "/_matrix/client/unstable/rooms/%s/aggregations/%s/%s?limit=1"
-            % (self.room, self.parent_id, RelationTypes.REPLACE),
+            f"/_matrix/client/unstable/rooms/{self.room}/aggregations"
+            f"/{self.parent_id}/{RelationTypes.REPLACE}?limit=1",
             access_token=self.user_token,
         )
         self.assertEqual(400, channel.code, channel.json_body)
@@ -986,9 +999,7 @@ class RelationsTestCase(unittest.HomeserverTestCase):
 
         # Request sync, but limit the timeline so it becomes limited (and includes
         # bundled aggregations).
-        filter = urllib.parse.quote_plus(
-            '{"room": {"timeline": {"limit": 2}}}'.encode()
-        )
+        filter = urllib.parse.quote_plus(b'{"room": {"timeline": {"limit": 2}}}')
         channel = self.make_request(
             "GET", f"/sync?filter={filter}", access_token=self.user_token
         )
@@ -1053,7 +1064,7 @@ class RelationsTestCase(unittest.HomeserverTestCase):
 
         channel = self.make_request(
             "GET",
-            "/rooms/%s/event/%s" % (self.room, self.parent_id),
+            f"/rooms/{self.room}/event/{self.parent_id}",
             access_token=self.user_token,
         )
         self.assertEqual(200, channel.code, channel.json_body)
@@ -1096,7 +1107,7 @@ class RelationsTestCase(unittest.HomeserverTestCase):
 
         channel = self.make_request(
             "GET",
-            "/rooms/%s/event/%s" % (self.room, reply),
+            f"/rooms/{self.room}/event/{reply}",
             access_token=self.user_token,
         )
         self.assertEqual(200, channel.code, channel.json_body)
@@ -1198,7 +1209,7 @@ class RelationsTestCase(unittest.HomeserverTestCase):
         # Request the original event.
         channel = self.make_request(
             "GET",
-            "/rooms/%s/event/%s" % (self.room, self.parent_id),
+            f"/rooms/{self.room}/event/{self.parent_id}",
             access_token=self.user_token,
         )
         self.assertEqual(200, channel.code, channel.json_body)
@@ -1217,102 +1228,6 @@ class RelationsTestCase(unittest.HomeserverTestCase):
             {"event_id": edit_event_id, "sender": self.user_id}, m_replace_dict
         )
 
-    def test_relations_redaction_redacts_edits(self) -> None:
-        """Test that edits of an event are redacted when the original event
-        is redacted.
-        """
-        # Send a new event
-        res = self.helper.send(self.room, body="Heyo!", tok=self.user_token)
-        original_event_id = res["event_id"]
-
-        # Add a relation
-        channel = self._send_relation(
-            RelationTypes.REPLACE,
-            "m.room.message",
-            parent_id=original_event_id,
-            content={
-                "msgtype": "m.text",
-                "body": "Wibble",
-                "m.new_content": {"msgtype": "m.text", "body": "First edit"},
-            },
-        )
-        self.assertEqual(200, channel.code, channel.json_body)
-
-        # Check the relation is returned
-        channel = self.make_request(
-            "GET",
-            "/_matrix/client/unstable/rooms/%s/relations/%s/m.replace/m.room.message"
-            % (self.room, original_event_id),
-            access_token=self.user_token,
-        )
-        self.assertEqual(200, channel.code, channel.json_body)
-
-        self.assertIn("chunk", channel.json_body)
-        self.assertEqual(len(channel.json_body["chunk"]), 1)
-
-        # Redact the original event
-        channel = self.make_request(
-            "PUT",
-            "/rooms/%s/redact/%s/%s"
-            % (self.room, original_event_id, "test_relations_redaction_redacts_edits"),
-            access_token=self.user_token,
-            content="{}",
-        )
-        self.assertEqual(200, channel.code, channel.json_body)
-
-        # Try to check for remaining m.replace relations
-        channel = self.make_request(
-            "GET",
-            "/_matrix/client/unstable/rooms/%s/relations/%s/m.replace/m.room.message"
-            % (self.room, original_event_id),
-            access_token=self.user_token,
-        )
-        self.assertEqual(200, channel.code, channel.json_body)
-
-        # Check that no relations are returned
-        self.assertIn("chunk", channel.json_body)
-        self.assertEqual(channel.json_body["chunk"], [])
-
-    def test_aggregations_redaction_prevents_access_to_aggregations(self) -> None:
-        """Test that annotations of an event are redacted when the original event
-        is redacted.
-        """
-        # Send a new event
-        res = self.helper.send(self.room, body="Hello!", tok=self.user_token)
-        original_event_id = res["event_id"]
-
-        # Add a relation
-        channel = self._send_relation(
-            RelationTypes.ANNOTATION, "m.reaction", key="👍", parent_id=original_event_id
-        )
-        self.assertEqual(200, channel.code, channel.json_body)
-
-        # Redact the original
-        channel = self.make_request(
-            "PUT",
-            "/rooms/%s/redact/%s/%s"
-            % (
-                self.room,
-                original_event_id,
-                "test_aggregations_redaction_prevents_access_to_aggregations",
-            ),
-            access_token=self.user_token,
-            content="{}",
-        )
-        self.assertEqual(200, channel.code, channel.json_body)
-
-        # Check that aggregations returns zero
-        channel = self.make_request(
-            "GET",
-            "/_matrix/client/unstable/rooms/%s/aggregations/%s/m.annotation/m.reaction"
-            % (self.room, original_event_id),
-            access_token=self.user_token,
-        )
-        self.assertEqual(200, channel.code, channel.json_body)
-
-        self.assertIn("chunk", channel.json_body)
-        self.assertEqual(channel.json_body["chunk"], [])
-
     def test_unknown_relations(self) -> None:
         """Unknown relations should be accepted."""
         channel = self._send_relation("m.relation.test", "m.room.test")
@@ -1321,8 +1236,7 @@ class RelationsTestCase(unittest.HomeserverTestCase):
 
         channel = self.make_request(
             "GET",
-            "/_matrix/client/unstable/rooms/%s/relations/%s?limit=1"
-            % (self.room, self.parent_id),
+            f"/_matrix/client/unstable/rooms/{self.room}/relations/{self.parent_id}?limit=1",
             access_token=self.user_token,
         )
         self.assertEqual(200, channel.code, channel.json_body)
@@ -1343,7 +1257,7 @@ class RelationsTestCase(unittest.HomeserverTestCase):
         # When bundling the unknown relation is not included.
         channel = self.make_request(
             "GET",
-            "/rooms/%s/event/%s" % (self.room, self.parent_id),
+            f"/rooms/{self.room}/event/{self.parent_id}",
             access_token=self.user_token,
         )
         self.assertEqual(200, channel.code, channel.json_body)
@@ -1352,8 +1266,7 @@ class RelationsTestCase(unittest.HomeserverTestCase):
         # But unknown relations can be directly queried.
         channel = self.make_request(
             "GET",
-            "/_matrix/client/unstable/rooms/%s/aggregations/%s?limit=1"
-            % (self.room, self.parent_id),
+            f"/_matrix/client/unstable/rooms/{self.room}/aggregations/{self.parent_id}?limit=1",
             access_token=self.user_token,
         )
         self.assertEqual(200, channel.code, channel.json_body)
@@ -1369,58 +1282,6 @@ class RelationsTestCase(unittest.HomeserverTestCase):
 
         raise AssertionError(f"Event {self.parent_id} not found in chunk")
 
-    def _send_relation(
-        self,
-        relation_type: str,
-        event_type: str,
-        key: Optional[str] = None,
-        content: Optional[dict] = None,
-        access_token: Optional[str] = None,
-        parent_id: Optional[str] = None,
-    ) -> FakeChannel:
-        """Helper function to send a relation pointing at `self.parent_id`
-
-        Args:
-            relation_type: One of `RelationTypes`
-            event_type: The type of the event to create
-            key: The aggregation key used for m.annotation relation type.
-            content: The content of the created event. Will be modified to configure
-                the m.relates_to key based on the other provided parameters.
-            access_token: The access token used to send the relation, defaults
-                to `self.user_token`
-            parent_id: The event_id this relation relates to. If None, then self.parent_id
-
-        Returns:
-            FakeChannel
-        """
-        if not access_token:
-            access_token = self.user_token
-
-        original_id = parent_id if parent_id else self.parent_id
-
-        if content is None:
-            content = {}
-        content["m.relates_to"] = {
-            "event_id": original_id,
-            "rel_type": relation_type,
-        }
-        if key is not None:
-            content["m.relates_to"]["key"] = key
-
-        channel = self.make_request(
-            "POST",
-            f"/_matrix/client/v3/rooms/{self.room}/send/{event_type}",
-            content,
-            access_token=access_token,
-        )
-        return channel
-
-    def _create_user(self, localpart: str) -> Tuple[str, str]:
-        user_id = self.register_user(localpart, "abc123")
-        access_token = self.login(localpart, "abc123")
-
-        return user_id, access_token
-
     def test_background_update(self) -> None:
         """Test the event_arbitrary_relations background update."""
         channel = self._send_relation(RelationTypes.ANNOTATION, "m.reaction", key="👍")
@@ -1482,3 +1343,112 @@ class RelationsTestCase(unittest.HomeserverTestCase):
             [ev["event_id"] for ev in channel.json_body["chunk"]],
             [annotation_event_id_good, thread_event_id],
         )
+
+
+class RelationRedactionTestCase(BaseRelationsTestCase):
+    """Test the behaviour of relations when the parent or child event is redacted."""
+
+    def _redact(self, event_id: str) -> None:
+        channel = self.make_request(
+            "POST",
+            f"/_matrix/client/r0/rooms/{self.room}/redact/{event_id}",
+            access_token=self.user_token,
+            content={},
+        )
+        self.assertEqual(200, channel.code, channel.json_body)
+
+    def test_redact_relation_annotation(self) -> None:
+        """Test that annotations of an event are properly handled after the
+        annotation is redacted.
+        """
+        channel = self._send_relation(RelationTypes.ANNOTATION, "m.reaction", "a")
+        self.assertEqual(200, channel.code, channel.json_body)
+        to_redact_event_id = channel.json_body["event_id"]
+
+        channel = self._send_relation(
+            RelationTypes.ANNOTATION, "m.reaction", "a", access_token=self.user2_token
+        )
+        self.assertEqual(200, channel.code, channel.json_body)
+
+        # Redact one of the reactions.
+        self._redact(to_redact_event_id)
+
+        # Ensure that the aggregations are correct.
+        channel = self.make_request(
+            "GET",
+            f"/_matrix/client/unstable/rooms/{self.room}/aggregations/{self.parent_id}",
+            access_token=self.user_token,
+        )
+        self.assertEqual(200, channel.code, channel.json_body)
+
+        self.assertEqual(
+            channel.json_body,
+            {"chunk": [{"type": "m.reaction", "key": "a", "count": 1}]},
+        )
+
+    def test_redact_relation_edit(self) -> None:
+        """Test that edits of an event are redacted when the original event
+        is redacted.
+        """
+        # Add a relation
+        channel = self._send_relation(
+            RelationTypes.REPLACE,
+            "m.room.message",
+            parent_id=self.parent_id,
+            content={
+                "msgtype": "m.text",
+                "body": "Wibble",
+                "m.new_content": {"msgtype": "m.text", "body": "First edit"},
+            },
+        )
+        self.assertEqual(200, channel.code, channel.json_body)
+
+        # Check the relation is returned
+        channel = self.make_request(
+            "GET",
+            f"/_matrix/client/unstable/rooms/{self.room}/relations"
+            f"/{self.parent_id}/m.replace/m.room.message",
+            access_token=self.user_token,
+        )
+        self.assertEqual(200, channel.code, channel.json_body)
+
+        self.assertIn("chunk", channel.json_body)
+        self.assertEqual(len(channel.json_body["chunk"]), 1)
+
+        # Redact the original event
+        self._redact(self.parent_id)
+
+        # Try to check for remaining m.replace relations
+        channel = self.make_request(
+            "GET",
+            f"/_matrix/client/unstable/rooms/{self.room}/relations"
+            f"/{self.parent_id}/m.replace/m.room.message",
+            access_token=self.user_token,
+        )
+        self.assertEqual(200, channel.code, channel.json_body)
+
+        # Check that no relations are returned
+        self.assertIn("chunk", channel.json_body)
+        self.assertEqual(channel.json_body["chunk"], [])
+
+    def test_redact_parent(self) -> None:
+        """Test that annotations of an event are redacted when the original event
+        is redacted.
+        """
+        # Add a relation
+        channel = self._send_relation(RelationTypes.ANNOTATION, "m.reaction", key="👍")
+        self.assertEqual(200, channel.code, channel.json_body)
+
+        # Redact the original event.
+        self._redact(self.parent_id)
+
+        # Check that aggregations returns zero
+        channel = self.make_request(
+            "GET",
+            f"/_matrix/client/unstable/rooms/{self.room}/aggregations/{self.parent_id}/m.annotation/m.reaction",
+            access_token=self.user_token,
+        )
+        self.assertEqual(200, channel.code, channel.json_body)
+
+        self.assertIn("chunk", channel.json_body)
+        self.assertEqual(channel.json_body["chunk"], [])