anonymousland-synapse/tests/rest/client/test_relations.py

# Copyright 2019 New Vector Ltd
# Copyright 2021 The Matrix.org Foundation C.I.C.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import itertools
import urllib.parse
from typing import Dict, List, Optional, Tuple

from synapse.api.constants import EventTypes, RelationTypes
from synapse.rest import admin
from synapse.rest.client import login, register, relations, room

from tests import unittest
from tests.server import FakeChannel


class RelationsTestCase(unittest.HomeserverTestCase):
    servlets = [
        relations.register_servlets,
        room.register_servlets,
        login.register_servlets,
        register.register_servlets,
        admin.register_servlets_for_client_rest_resource,
    ]
    hijack_auth = False

    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.
        config["use_frozen_dicts"] = True

        return config

    def prepare(self, reactor, clock, hs):
        self.store = hs.get_datastore()

        self.user_id, self.user_token = self._create_user("alice")
        self.user2_id, self.user2_token = self._create_user("bob")

        self.room = self.helper.create_room_as(self.user_id, tok=self.user_token)
        self.helper.join(self.room, user=self.user2_id, tok=self.user2_token)
        res = self.helper.send(self.room, body="Hi!", tok=self.user_token)
        self.parent_id = res["event_id"]

    def test_send_relation(self):
        """Tests that sending a relation using the new /send_relation works
        creates the right shape of event.
        """

        channel = self._send_relation(RelationTypes.ANNOTATION, "m.reaction", key="👍")
        self.assertEquals(200, channel.code, channel.json_body)

        event_id = channel.json_body["event_id"]

        channel = self.make_request(
            "GET",
            "/rooms/%s/event/%s" % (self.room, event_id),
            access_token=self.user_token,
        )
        self.assertEquals(200, channel.code, channel.json_body)

        self.assert_dict(
            {
                "type": "m.reaction",
                "sender": self.user_id,
                "content": {
                    "m.relates_to": {
                        "event_id": self.parent_id,
                        "key": "👍",
                        "rel_type": RelationTypes.ANNOTATION,
                    }
                },
            },
            channel.json_body,
        )

    def test_deny_membership(self):
        """Test that we deny relations on membership events"""
        channel = self._send_relation(RelationTypes.ANNOTATION, EventTypes.Member)
        self.assertEquals(400, channel.code, channel.json_body)

    def test_deny_invalid_event(self):
        """Test that we deny relations on non-existant events"""
        channel = self._send_relation(
            RelationTypes.ANNOTATION,
            EventTypes.Message,
            parent_id="foo",
            content={"body": "foo", "msgtype": "m.text"},
        )
        self.assertEquals(400, channel.code, channel.json_body)

        # Unless that event is referenced from another event!
        self.get_success(
            self.hs.get_datastore().db_pool.simple_insert(
                table="event_relations",
                values={
                    "event_id": "bar",
                    "relates_to_id": "foo",
                    "relation_type": RelationTypes.THREAD,
                },
                desc="test_deny_invalid_event",
            )
        )
        channel = self._send_relation(
            RelationTypes.THREAD,
            EventTypes.Message,
            parent_id="foo",
            content={"body": "foo", "msgtype": "m.text"},
        )
        self.assertEquals(200, channel.code, channel.json_body)

    def test_deny_invalid_room(self):
        """Test that we deny relations on non-existant events"""
        # Create another room and send a message in it.
        room2 = self.helper.create_room_as(self.user_id, tok=self.user_token)
        res = self.helper.send(room2, body="Hi!", tok=self.user_token)
        parent_id = res["event_id"]

        # Attempt to send an annotation to that event.
        channel = self._send_relation(
            RelationTypes.ANNOTATION, "m.reaction", parent_id=parent_id, key="A"
        )
        self.assertEquals(400, channel.code, channel.json_body)

    def test_deny_double_react(self):
        """Test that we deny relations on membership events"""
        channel = self._send_relation(RelationTypes.ANNOTATION, "m.reaction", key="a")
        self.assertEquals(200, channel.code, channel.json_body)

        channel = self._send_relation(RelationTypes.ANNOTATION, "m.reaction", "a")
        self.assertEquals(400, channel.code, channel.json_body)

    def test_deny_forked_thread(self):
        """It is invalid to start a thread off a thread."""
        channel = self._send_relation(
            RelationTypes.THREAD,
            "m.room.message",
            content={"msgtype": "m.text", "body": "foo"},
            parent_id=self.parent_id,
        )
        self.assertEquals(200, channel.code, channel.json_body)
        parent_id = channel.json_body["event_id"]

        channel = self._send_relation(
            RelationTypes.THREAD,
            "m.room.message",
            content={"msgtype": "m.text", "body": "foo"},
            parent_id=parent_id,
        )
        self.assertEquals(400, channel.code, channel.json_body)

    def test_basic_paginate_relations(self):
        """Tests that calling pagination API correctly the latest relations."""
        channel = self._send_relation(RelationTypes.ANNOTATION, "m.reaction", "a")
        self.assertEquals(200, channel.code, channel.json_body)

        channel = self._send_relation(RelationTypes.ANNOTATION, "m.reaction", "b")
        self.assertEquals(200, channel.code, channel.json_body)
        annotation_id = channel.json_body["event_id"]

        channel = self.make_request(
            "GET",
            "/_matrix/client/unstable/rooms/%s/relations/%s?limit=1"
            % (self.room, self.parent_id),
            access_token=self.user_token,
        )
        self.assertEquals(200, channel.code, channel.json_body)

        # We expect to get back a single pagination result, which is the full
        # relation event we sent above.
        self.assertEquals(len(channel.json_body["chunk"]), 1, channel.json_body)
        self.assert_dict(
            {"event_id": annotation_id, "sender": self.user_id, "type": "m.reaction"},
            channel.json_body["chunk"][0],
        )

        # We also expect to get the original event (the id of which is self.parent_id)
        self.assertEquals(
            channel.json_body["original_event"]["event_id"], self.parent_id
        )

        # Make sure next_batch has something in it that looks like it could be a
        # valid token.
        self.assertIsInstance(
            channel.json_body.get("next_batch"), str, channel.json_body
        )

    def test_repeated_paginate_relations(self):
        """Test that if we paginate using a limit and tokens then we get the
        expected events.
        """

        expected_event_ids = []
        for idx in range(10):
            channel = self._send_relation(
                RelationTypes.ANNOTATION, "m.reaction", chr(ord("a") + idx)
            )
            self.assertEquals(200, channel.code, channel.json_body)
            expected_event_ids.append(channel.json_body["event_id"])

        prev_token: Optional[str] = None
        found_event_ids: List[str] = []
        for _ in range(20):
            from_token = ""
            if prev_token:
                from_token = "&from=" + prev_token

            channel = self.make_request(
                "GET",
                "/_matrix/client/unstable/rooms/%s/relations/%s?limit=1%s"
                % (self.room, self.parent_id, from_token),
                access_token=self.user_token,
            )
            self.assertEquals(200, channel.code, channel.json_body)

            found_event_ids.extend(e["event_id"] for e in channel.json_body["chunk"])
            next_batch = channel.json_body.get("next_batch")

            self.assertNotEquals(prev_token, next_batch)
            prev_token = next_batch

            if not prev_token:
                break

        # We paginated backwards, so reverse
        found_event_ids.reverse()
        self.assertEquals(found_event_ids, expected_event_ids)

    def test_aggregation_pagination_groups(self):
        """Test that we can paginate annotation groups correctly."""

        # We need to create ten separate users to send each reaction.
        access_tokens = [self.user_token, self.user2_token]
        idx = 0
        while len(access_tokens) < 10:
            user_id, token = self._create_user("test" + str(idx))
            idx += 1

            self.helper.join(self.room, user=user_id, tok=token)
            access_tokens.append(token)

        idx = 0
        sent_groups = {"👍": 10, "a": 7, "b": 5, "c": 3, "d": 2, "e": 1}
        for key in itertools.chain.from_iterable(
            itertools.repeat(key, num) for key, num in sent_groups.items()
        ):
            channel = self._send_relation(
                RelationTypes.ANNOTATION,
                "m.reaction",
                key=key,
                access_token=access_tokens[idx],
            )
            self.assertEquals(200, channel.code, channel.json_body)

            idx += 1
            idx %= len(access_tokens)

        prev_token: Optional[str] = None
        found_groups: Dict[str, int] = {}
        for _ in range(20):
            from_token = ""
            if prev_token:
                from_token = "&from=" + prev_token

            channel = self.make_request(
                "GET",
                "/_matrix/client/unstable/rooms/%s/aggregations/%s?limit=1%s"
                % (self.room, self.parent_id, from_token),
                access_token=self.user_token,
            )
            self.assertEquals(200, channel.code, channel.json_body)

            self.assertEqual(len(channel.json_body["chunk"]), 1, channel.json_body)

            for groups in channel.json_body["chunk"]:
                # We only expect reactions
                self.assertEqual(groups["type"], "m.reaction", channel.json_body)

                # We should only see each key once
                self.assertNotIn(groups["key"], found_groups, channel.json_body)

                found_groups[groups["key"]] = groups["count"]

            next_batch = channel.json_body.get("next_batch")

            self.assertNotEquals(prev_token, next_batch)
            prev_token = next_batch

            if not prev_token:
                break

        self.assertEquals(sent_groups, found_groups)

    def test_aggregation_pagination_within_group(self):
        """Test that we can paginate within an annotation group."""

        # We need to create ten separate users to send each reaction.
        access_tokens = [self.user_token, self.user2_token]
        idx = 0
        while len(access_tokens) < 10:
            user_id, token = self._create_user("test" + str(idx))
            idx += 1

            self.helper.join(self.room, user=user_id, tok=token)
            access_tokens.append(token)

        idx = 0
        expected_event_ids = []
        for _ in range(10):
            channel = self._send_relation(
                RelationTypes.ANNOTATION,
                "m.reaction",
                key="👍",
                access_token=access_tokens[idx],
            )
            self.assertEquals(200, channel.code, channel.json_body)
            expected_event_ids.append(channel.json_body["event_id"])

            idx += 1

        # Also send a different type of reaction so that we test we don't see it
        channel = self._send_relation(RelationTypes.ANNOTATION, "m.reaction", key="a")
        self.assertEquals(200, channel.code, channel.json_body)

        prev_token: Optional[str] = None
        found_event_ids: List[str] = []
        encoded_key = urllib.parse.quote_plus("👍".encode())
        for _ in range(20):
            from_token = ""
            if prev_token:
                from_token = "&from=" + prev_token

            channel = self.make_request(
                "GET",
                "/_matrix/client/unstable/rooms/%s"
                "/aggregations/%s/%s/m.reaction/%s?limit=1%s"
                % (
                    self.room,
                    self.parent_id,
                    RelationTypes.ANNOTATION,
                    encoded_key,
                    from_token,
                ),
                access_token=self.user_token,
            )
            self.assertEquals(200, channel.code, channel.json_body)

            self.assertEqual(len(channel.json_body["chunk"]), 1, channel.json_body)

            found_event_ids.extend(e["event_id"] for e in channel.json_body["chunk"])

            next_batch = channel.json_body.get("next_batch")

            self.assertNotEquals(prev_token, next_batch)
            prev_token = next_batch

            if not prev_token:
                break

        # We paginated backwards, so reverse
        found_event_ids.reverse()
        self.assertEquals(found_event_ids, expected_event_ids)

    def test_aggregation(self):
        """Test that annotations get correctly aggregated."""

        channel = self._send_relation(RelationTypes.ANNOTATION, "m.reaction", "a")
        self.assertEquals(200, channel.code, channel.json_body)

        channel = self._send_relation(
            RelationTypes.ANNOTATION, "m.reaction", "a", access_token=self.user2_token
        )
        self.assertEquals(200, channel.code, channel.json_body)

        channel = self._send_relation(RelationTypes.ANNOTATION, "m.reaction", "b")
        self.assertEquals(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.assertEquals(200, channel.code, channel.json_body)

        self.assertEquals(
            channel.json_body,
            {
                "chunk": [
                    {"type": "m.reaction", "key": "a", "count": 2},
                    {"type": "m.reaction", "key": "b", "count": 1},
                ]
            },
        )

    def test_aggregation_redactions(self):
        """Test that annotations get correctly aggregated after a redaction."""

        channel = self._send_relation(RelationTypes.ANNOTATION, "m.reaction", "a")
        self.assertEquals(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.assertEquals(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.assertEquals(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.assertEquals(200, channel.code, channel.json_body)

        self.assertEquals(
            channel.json_body,
            {"chunk": [{"type": "m.reaction", "key": "a", "count": 1}]},
        )

    def test_aggregation_must_be_annotation(self):
        """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),
            access_token=self.user_token,
        )
        self.assertEquals(400, channel.code, channel.json_body)

    @unittest.override_config({"experimental_features": {"msc3440_enabled": True}})
    def test_aggregation_get_event(self):
        """Test that annotations, references, and threads get correctly bundled when
        getting the parent event.
        """

        channel = self._send_relation(RelationTypes.ANNOTATION, "m.reaction", "a")
        self.assertEquals(200, channel.code, channel.json_body)

        channel = self._send_relation(
            RelationTypes.ANNOTATION, "m.reaction", "a", access_token=self.user2_token
        )
        self.assertEquals(200, channel.code, channel.json_body)

        channel = self._send_relation(RelationTypes.ANNOTATION, "m.reaction", "b")
        self.assertEquals(200, channel.code, channel.json_body)

        channel = self._send_relation(RelationTypes.REFERENCE, "m.room.test")
        self.assertEquals(200, channel.code, channel.json_body)
        reply_1 = channel.json_body["event_id"]

        channel = self._send_relation(RelationTypes.REFERENCE, "m.room.test")
        self.assertEquals(200, channel.code, channel.json_body)
        reply_2 = channel.json_body["event_id"]

        channel = self._send_relation(RelationTypes.THREAD, "m.room.test")
        self.assertEquals(200, channel.code, channel.json_body)

        channel = self._send_relation(RelationTypes.THREAD, "m.room.test")
        self.assertEquals(200, channel.code, channel.json_body)
        thread_2 = channel.json_body["event_id"]

        channel = self.make_request(
            "GET",
            "/rooms/%s/event/%s" % (self.room, self.parent_id),
            access_token=self.user_token,
        )
        self.assertEquals(200, channel.code, channel.json_body)

        self.assertEquals(
            channel.json_body["unsigned"].get("m.relations"),
            {
                RelationTypes.ANNOTATION: {
                    "chunk": [
                        {"type": "m.reaction", "key": "a", "count": 2},
                        {"type": "m.reaction", "key": "b", "count": 1},
                    ]
                },
                RelationTypes.REFERENCE: {
                    "chunk": [{"event_id": reply_1}, {"event_id": reply_2}]
                },
                RelationTypes.THREAD: {
                    "count": 2,
                    "latest_event": {
                        "age": 100,
                        "content": {
                            "m.relates_to": {
                                "event_id": self.parent_id,
                                "rel_type": RelationTypes.THREAD,
                            }
                        },
                        "event_id": thread_2,
                        "origin_server_ts": 1600,
                        "room_id": self.room,
                        "sender": self.user_id,
                        "type": "m.room.test",
                        "unsigned": {"age": 100},
                        "user_id": self.user_id,
                    },
                },
            },
        )

    def test_edit(self):
        """Test that a simple edit works."""

        new_body = {"msgtype": "m.text", "body": "I've been edited!"}
        channel = self._send_relation(
            RelationTypes.REPLACE,
            "m.room.message",
            content={"msgtype": "m.text", "body": "foo", "m.new_content": new_body},
        )
        self.assertEquals(200, channel.code, channel.json_body)

        edit_event_id = channel.json_body["event_id"]

        channel = self.make_request(
            "GET",
            "/rooms/%s/event/%s" % (self.room, self.parent_id),
            access_token=self.user_token,
        )
        self.assertEquals(200, channel.code, channel.json_body)

        self.assertEquals(channel.json_body["content"], new_body)

        relations_dict = channel.json_body["unsigned"].get("m.relations")
        self.assertIn(RelationTypes.REPLACE, relations_dict)

        m_replace_dict = relations_dict[RelationTypes.REPLACE]
        for key in ["event_id", "sender", "origin_server_ts"]:
            self.assertIn(key, m_replace_dict)

        self.assert_dict(
            {"event_id": edit_event_id, "sender": self.user_id}, m_replace_dict
        )

    def test_multi_edit(self):
        """Test that multiple edits, including attempts by people who
        shouldn't be allowed, are correctly handled.
        """

        channel = self._send_relation(
            RelationTypes.REPLACE,
            "m.room.message",
            content={
                "msgtype": "m.text",
                "body": "Wibble",
                "m.new_content": {"msgtype": "m.text", "body": "First edit"},
            },
        )
        self.assertEquals(200, channel.code, channel.json_body)

        new_body = {"msgtype": "m.text", "body": "I've been edited!"}
        channel = self._send_relation(
            RelationTypes.REPLACE,
            "m.room.message",
            content={"msgtype": "m.text", "body": "foo", "m.new_content": new_body},
        )
        self.assertEquals(200, channel.code, channel.json_body)

        edit_event_id = channel.json_body["event_id"]

        channel = self._send_relation(
            RelationTypes.REPLACE,
            "m.room.message.WRONG_TYPE",
            content={
                "msgtype": "m.text",
                "body": "Wibble",
                "m.new_content": {"msgtype": "m.text", "body": "Edit, but wrong type"},
            },
        )
        self.assertEquals(200, channel.code, channel.json_body)

        channel = self.make_request(
            "GET",
            "/rooms/%s/event/%s" % (self.room, self.parent_id),
            access_token=self.user_token,
        )
        self.assertEquals(200, channel.code, channel.json_body)

        self.assertEquals(channel.json_body["content"], new_body)

        relations_dict = channel.json_body["unsigned"].get("m.relations")
        self.assertIn(RelationTypes.REPLACE, relations_dict)

        m_replace_dict = relations_dict[RelationTypes.REPLACE]
        for key in ["event_id", "sender", "origin_server_ts"]:
            self.assertIn(key, m_replace_dict)

        self.assert_dict(
            {"event_id": edit_event_id, "sender": self.user_id}, m_replace_dict
        )

    def test_edit_reply(self):
        """Test that editing a reply works."""

        # Create a reply to edit.
        channel = self._send_relation(
            RelationTypes.REFERENCE,
            "m.room.message",
            content={"msgtype": "m.text", "body": "A reply!"},
        )
        self.assertEquals(200, channel.code, channel.json_body)
        reply = channel.json_body["event_id"]

        new_body = {"msgtype": "m.text", "body": "I've been edited!"}
        channel = self._send_relation(
            RelationTypes.REPLACE,
            "m.room.message",
            content={"msgtype": "m.text", "body": "foo", "m.new_content": new_body},
            parent_id=reply,
        )
        self.assertEquals(200, channel.code, channel.json_body)

        edit_event_id = channel.json_body["event_id"]

        channel = self.make_request(
            "GET",
            "/rooms/%s/event/%s" % (self.room, reply),
            access_token=self.user_token,
        )
        self.assertEquals(200, channel.code, channel.json_body)

        # We expect to see the new body in the dict, as well as the reference
        # metadata sill intact.
        self.assertDictContainsSubset(new_body, channel.json_body["content"])
        self.assertDictContainsSubset(
            {
                "m.relates_to": {
                    "event_id": self.parent_id,
                    "rel_type": "m.reference",
                }
            },
            channel.json_body["content"],
        )

        # We expect that the edit relation appears in the unsigned relations
        # section.
        relations_dict = channel.json_body["unsigned"].get("m.relations")
        self.assertIn(RelationTypes.REPLACE, relations_dict)

        m_replace_dict = relations_dict[RelationTypes.REPLACE]
        for key in ["event_id", "sender", "origin_server_ts"]:
            self.assertIn(key, m_replace_dict)

        self.assert_dict(
            {"event_id": edit_event_id, "sender": self.user_id}, m_replace_dict
        )

    def test_relations_redaction_redacts_edits(self):
        """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.assertEquals(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.assertEquals(200, channel.code, channel.json_body)

        self.assertIn("chunk", channel.json_body)
        self.assertEquals(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.assertEquals(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.assertEquals(200, channel.code, channel.json_body)

        # Check that no relations are returned
        self.assertIn("chunk", channel.json_body)
        self.assertEquals(channel.json_body["chunk"], [])

    def test_aggregations_redaction_prevents_access_to_aggregations(self):
        """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.assertEquals(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.assertEquals(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.assertEquals(200, channel.code, channel.json_body)

        self.assertIn("chunk", channel.json_body)
        self.assertEquals(channel.json_body["chunk"], [])

    def test_unknown_relations(self):
        """Unknown relations should be accepted."""
        channel = self._send_relation("m.relation.test", "m.room.test")
        self.assertEquals(200, channel.code, channel.json_body)
        event_id = channel.json_body["event_id"]

        channel = self.make_request(
            "GET",
            "/_matrix/client/unstable/rooms/%s/relations/%s?limit=1"
            % (self.room, self.parent_id),
            access_token=self.user_token,
        )
        self.assertEquals(200, channel.code, channel.json_body)

        # We expect to get back a single pagination result, which is the full
        # relation event we sent above.
        self.assertEquals(len(channel.json_body["chunk"]), 1, channel.json_body)
        self.assert_dict(
            {"event_id": event_id, "sender": self.user_id, "type": "m.room.test"},
            channel.json_body["chunk"][0],
        )

        # We also expect to get the original event (the id of which is self.parent_id)
        self.assertEquals(
            channel.json_body["original_event"]["event_id"], self.parent_id
        )

        # When bundling the unknown relation is not included.
        channel = self.make_request(
            "GET",
            "/rooms/%s/event/%s" % (self.room, self.parent_id),
            access_token=self.user_token,
        )
        self.assertEquals(200, channel.code, channel.json_body)
        self.assertNotIn("m.relations", channel.json_body["unsigned"])

        # 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),
            access_token=self.user_token,
        )
        self.assertEquals(200, channel.code, channel.json_body)
        self.assertEquals(channel.json_body["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.
            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

        query = ""
        if key:
            query = "?key=" + urllib.parse.quote_plus(key.encode("utf-8"))

        original_id = parent_id if parent_id else self.parent_id

        channel = self.make_request(
            "POST",
            "/_matrix/client/unstable/rooms/%s/send_relation/%s/%s/%s%s"
            % (self.room, original_id, relation_type, event_type, query),
            content or {},
            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):
        """Test the event_arbitrary_relations background update."""
        channel = self._send_relation(RelationTypes.ANNOTATION, "m.reaction", key="👍")
        self.assertEquals(200, channel.code, channel.json_body)
        annotation_event_id_good = channel.json_body["event_id"]

        channel = self._send_relation(RelationTypes.ANNOTATION, "m.reaction", key="A")
        self.assertEquals(200, channel.code, channel.json_body)
        annotation_event_id_bad = channel.json_body["event_id"]

        channel = self._send_relation(RelationTypes.THREAD, "m.room.test")
        self.assertEquals(200, channel.code, channel.json_body)
        thread_event_id = channel.json_body["event_id"]

        # Clean-up the table as if the inserts did not happen during event creation.
        self.get_success(
            self.store.db_pool.simple_delete_many(
                table="event_relations",
                column="event_id",
                iterable=(annotation_event_id_bad, thread_event_id),
                keyvalues={},
                desc="RelationsTestCase.test_background_update",
            )
        )

        # Only the "good" annotation should be found.
        channel = self.make_request(
            "GET",
            f"/_matrix/client/unstable/rooms/{self.room}/relations/{self.parent_id}?limit=10",
            access_token=self.user_token,
        )
        self.assertEquals(200, channel.code, channel.json_body)
        self.assertEquals(
            [ev["event_id"] for ev in channel.json_body["chunk"]],
            [annotation_event_id_good],
        )

        # Insert and run the background update.
        self.get_success(
            self.store.db_pool.simple_insert(
                "background_updates",
                {"update_name": "event_arbitrary_relations", "progress_json": "{}"},
            )
        )

        # Ugh, have to reset this flag
        self.store.db_pool.updates._all_done = False
        self.wait_for_background_updates()

        # The "good" annotation and the thread should be found, but not the "bad"
        # annotation.
        channel = self.make_request(
            "GET",
            f"/_matrix/client/unstable/rooms/{self.room}/relations/{self.parent_id}?limit=10",
            access_token=self.user_token,
        )
        self.assertEquals(200, channel.code, channel.json_body)
        self.assertCountEqual(
            [ev["event_id"] for ev in channel.json_body["chunk"]],
            [annotation_event_id_good, thread_event_id],
        )