MatrixSynapse/tests/storage/test_state.py

# Copyright 2018-2021 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 logging

from frozendict import frozendict

from twisted.test.proto_helpers import MemoryReactor

from synapse.api.constants import EventTypes, Membership
from synapse.api.room_versions import RoomVersions
from synapse.events import EventBase
from synapse.server import HomeServer
from synapse.types import JsonDict, RoomID, StateMap, UserID
from synapse.types.state import StateFilter
from synapse.util import Clock

from tests.unittest import HomeserverTestCase, TestCase

logger = logging.getLogger(__name__)


class StateStoreTestCase(HomeserverTestCase):
    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
        self.store = hs.get_datastores().main
        self.storage = hs.get_storage_controllers()
        self.state_datastore = self.storage.state.stores.state
        self.event_builder_factory = hs.get_event_builder_factory()
        self.event_creation_handler = hs.get_event_creation_handler()

        self.u_alice = UserID.from_string("@alice:test")
        self.u_bob = UserID.from_string("@bob:test")

        self.room = RoomID.from_string("!abc123:test")

        self.get_success(
            self.store.store_room(
                self.room.to_string(),
                room_creator_user_id="@creator:text",
                is_public=True,
                room_version=RoomVersions.V1,
            )
        )

    def inject_state_event(
        self, room: RoomID, sender: UserID, typ: str, state_key: str, content: JsonDict
    ) -> EventBase:
        builder = self.event_builder_factory.for_room_version(
            RoomVersions.V1,
            {
                "type": typ,
                "sender": sender.to_string(),
                "state_key": state_key,
                "room_id": room.to_string(),
                "content": content,
            },
        )

        event, context = self.get_success(
            self.event_creation_handler.create_new_client_event(builder)
        )

        assert self.storage.persistence is not None
        self.get_success(self.storage.persistence.persist_event(event, context))

        return event

    def assertStateMapEqual(
        self, s1: StateMap[EventBase], s2: StateMap[EventBase]
    ) -> None:
        for t in s1:
            # just compare event IDs for simplicity
            self.assertEqual(s1[t].event_id, s2[t].event_id)
        self.assertEqual(len(s1), len(s2))

    def test_get_state_groups_ids(self) -> None:
        e1 = self.inject_state_event(self.room, self.u_alice, EventTypes.Create, "", {})
        e2 = self.inject_state_event(
            self.room, self.u_alice, EventTypes.Name, "", {"name": "test room"}
        )

        state_group_map = self.get_success(
            self.storage.state.get_state_groups_ids(
                self.room.to_string(), [e2.event_id]
            )
        )
        self.assertEqual(len(state_group_map), 1)
        state_map = list(state_group_map.values())[0]
        self.assertDictEqual(
            state_map,
            {(EventTypes.Create, ""): e1.event_id, (EventTypes.Name, ""): e2.event_id},
        )

    def test_get_state_groups(self) -> None:
        e1 = self.inject_state_event(self.room, self.u_alice, EventTypes.Create, "", {})
        e2 = self.inject_state_event(
            self.room, self.u_alice, EventTypes.Name, "", {"name": "test room"}
        )

        state_group_map = self.get_success(
            self.storage.state.get_state_groups(self.room.to_string(), [e2.event_id])
        )
        self.assertEqual(len(state_group_map), 1)
        state_list = list(state_group_map.values())[0]

        self.assertEqual({ev.event_id for ev in state_list}, {e1.event_id, e2.event_id})

    def test_get_state_for_event(self) -> None:
        # this defaults to a linear DAG as each new injection defaults to whatever
        # forward extremities are currently in the DB for this room.
        e1 = self.inject_state_event(self.room, self.u_alice, EventTypes.Create, "", {})
        e2 = self.inject_state_event(
            self.room, self.u_alice, EventTypes.Name, "", {"name": "test room"}
        )
        e3 = self.inject_state_event(
            self.room,
            self.u_alice,
            EventTypes.Member,
            self.u_alice.to_string(),
            {"membership": Membership.JOIN},
        )
        e4 = self.inject_state_event(
            self.room,
            self.u_bob,
            EventTypes.Member,
            self.u_bob.to_string(),
            {"membership": Membership.JOIN},
        )
        e5 = self.inject_state_event(
            self.room,
            self.u_bob,
            EventTypes.Member,
            self.u_bob.to_string(),
            {"membership": Membership.LEAVE},
        )

        # check we get the full state as of the final event
        state = self.get_success(self.storage.state.get_state_for_event(e5.event_id))

        self.assertIsNotNone(e4)

        self.assertStateMapEqual(
            {
                (e1.type, e1.state_key): e1,
                (e2.type, e2.state_key): e2,
                (e3.type, e3.state_key): e3,
                # e4 is overwritten by e5
                (e5.type, e5.state_key): e5,
            },
            state,
        )

        # check we can filter to the m.room.name event (with a '' state key)
        state = self.get_success(
            self.storage.state.get_state_for_event(
                e5.event_id, StateFilter.from_types([(EventTypes.Name, "")])
            )
        )

        self.assertStateMapEqual({(e2.type, e2.state_key): e2}, state)

        # check we can filter to the m.room.name event (with a wildcard None state key)
        state = self.get_success(
            self.storage.state.get_state_for_event(
                e5.event_id, StateFilter.from_types([(EventTypes.Name, None)])
            )
        )

        self.assertStateMapEqual({(e2.type, e2.state_key): e2}, state)

        # check we can grab the m.room.member events (with a wildcard None state key)
        state = self.get_success(
            self.storage.state.get_state_for_event(
                e5.event_id, StateFilter.from_types([(EventTypes.Member, None)])
            )
        )

        self.assertStateMapEqual(
            {(e3.type, e3.state_key): e3, (e5.type, e5.state_key): e5}, state
        )

        # check we can grab a specific room member without filtering out the
        # other event types
        state = self.get_success(
            self.storage.state.get_state_for_event(
                e5.event_id,
                state_filter=StateFilter(
                    types=frozendict(
                        {EventTypes.Member: frozenset({self.u_alice.to_string()})}
                    ),
                    include_others=True,
                ),
            )
        )

        self.assertStateMapEqual(
            {
                (e1.type, e1.state_key): e1,
                (e2.type, e2.state_key): e2,
                (e3.type, e3.state_key): e3,
            },
            state,
        )

        # check that we can grab everything except members
        state = self.get_success(
            self.storage.state.get_state_for_event(
                e5.event_id,
                state_filter=StateFilter(
                    types=frozendict({EventTypes.Member: frozenset()}),
                    include_others=True,
                ),
            )
        )

        self.assertStateMapEqual(
            {(e1.type, e1.state_key): e1, (e2.type, e2.state_key): e2}, state
        )

        #######################################################
        # _get_state_for_group_using_cache tests against a full cache
        #######################################################

        room_id = self.room.to_string()
        group_ids = self.get_success(
            self.storage.state.get_state_groups_ids(room_id, [e5.event_id])
        )
        group = list(group_ids.keys())[0]

        # test _get_state_for_group_using_cache correctly filters out members
        # with types=[]
        (state_dict, is_all,) = self.state_datastore._get_state_for_group_using_cache(
            self.state_datastore._state_group_cache,
            group,
            state_filter=StateFilter(
                types=frozendict({EventTypes.Member: frozenset()}), include_others=True
            ),
        )

        self.assertEqual(is_all, True)
        self.assertDictEqual(
            {
                (e1.type, e1.state_key): e1.event_id,
                (e2.type, e2.state_key): e2.event_id,
            },
            state_dict,
        )

        (state_dict, is_all,) = self.state_datastore._get_state_for_group_using_cache(
            self.state_datastore._state_group_members_cache,
            group,
            state_filter=StateFilter(
                types=frozendict({EventTypes.Member: frozenset()}), include_others=True
            ),
        )

        self.assertEqual(is_all, True)
        self.assertDictEqual({}, state_dict)

        # test _get_state_for_group_using_cache correctly filters in members
        # with wildcard types
        (state_dict, is_all,) = self.state_datastore._get_state_for_group_using_cache(
            self.state_datastore._state_group_cache,
            group,
            state_filter=StateFilter(
                types=frozendict({EventTypes.Member: None}), include_others=True
            ),
        )

        self.assertEqual(is_all, True)
        self.assertDictEqual(
            {
                (e1.type, e1.state_key): e1.event_id,
                (e2.type, e2.state_key): e2.event_id,
            },
            state_dict,
        )

        (state_dict, is_all,) = self.state_datastore._get_state_for_group_using_cache(
            self.state_datastore._state_group_members_cache,
            group,
            state_filter=StateFilter(
                types=frozendict({EventTypes.Member: None}), include_others=True
            ),
        )

        self.assertEqual(is_all, True)
        self.assertDictEqual(
            {
                (e3.type, e3.state_key): e3.event_id,
                # e4 is overwritten by e5
                (e5.type, e5.state_key): e5.event_id,
            },
            state_dict,
        )

        # test _get_state_for_group_using_cache correctly filters in members
        # with specific types
        (state_dict, is_all,) = self.state_datastore._get_state_for_group_using_cache(
            self.state_datastore._state_group_cache,
            group,
            state_filter=StateFilter(
                types=frozendict({EventTypes.Member: frozenset({e5.state_key})}),
                include_others=True,
            ),
        )

        self.assertEqual(is_all, True)
        self.assertDictEqual(
            {
                (e1.type, e1.state_key): e1.event_id,
                (e2.type, e2.state_key): e2.event_id,
            },
            state_dict,
        )

        (state_dict, is_all,) = self.state_datastore._get_state_for_group_using_cache(
            self.state_datastore._state_group_members_cache,
            group,
            state_filter=StateFilter(
                types=frozendict({EventTypes.Member: frozenset({e5.state_key})}),
                include_others=True,
            ),
        )

        self.assertEqual(is_all, True)
        self.assertDictEqual({(e5.type, e5.state_key): e5.event_id}, state_dict)

        # test _get_state_for_group_using_cache correctly filters in members
        # with specific types
        (state_dict, is_all,) = self.state_datastore._get_state_for_group_using_cache(
            self.state_datastore._state_group_members_cache,
            group,
            state_filter=StateFilter(
                types=frozendict({EventTypes.Member: frozenset({e5.state_key})}),
                include_others=False,
            ),
        )

        self.assertEqual(is_all, True)
        self.assertDictEqual({(e5.type, e5.state_key): e5.event_id}, state_dict)

        #######################################################
        # deliberately remove e2 (room name) from the _state_group_cache

        cache_entry = self.state_datastore._state_group_cache.get(group)
        state_dict_ids = cache_entry.value

        self.assertEqual(cache_entry.full, True)
        self.assertEqual(cache_entry.known_absent, set())
        self.assertDictEqual(
            state_dict_ids,
            {
                (e1.type, e1.state_key): e1.event_id,
                (e2.type, e2.state_key): e2.event_id,
            },
        )

        state_dict_ids.pop((e2.type, e2.state_key))
        self.state_datastore._state_group_cache.invalidate(group)
        self.state_datastore._state_group_cache.update(
            sequence=self.state_datastore._state_group_cache.sequence,
            key=group,
            value=state_dict_ids,
            # list fetched keys so it knows it's partial
            fetched_keys=((e1.type, e1.state_key),),
        )

        cache_entry = self.state_datastore._state_group_cache.get(group)
        state_dict_ids = cache_entry.value

        self.assertEqual(cache_entry.full, False)
        self.assertEqual(cache_entry.known_absent, set())
        self.assertDictEqual(state_dict_ids, {})

        ############################################
        # test that things work with a partial cache

        # test _get_state_for_group_using_cache correctly filters out members
        # with types=[]
        room_id = self.room.to_string()
        (state_dict, is_all,) = self.state_datastore._get_state_for_group_using_cache(
            self.state_datastore._state_group_cache,
            group,
            state_filter=StateFilter(
                types=frozendict({EventTypes.Member: frozenset()}), include_others=True
            ),
        )

        self.assertEqual(is_all, False)
        self.assertDictEqual({}, state_dict)

        room_id = self.room.to_string()
        (state_dict, is_all,) = self.state_datastore._get_state_for_group_using_cache(
            self.state_datastore._state_group_members_cache,
            group,
            state_filter=StateFilter(
                types=frozendict({EventTypes.Member: frozenset()}), include_others=True
            ),
        )

        self.assertEqual(is_all, True)
        self.assertDictEqual({}, state_dict)

        # test _get_state_for_group_using_cache correctly filters in members
        # wildcard types
        (state_dict, is_all,) = self.state_datastore._get_state_for_group_using_cache(
            self.state_datastore._state_group_cache,
            group,
            state_filter=StateFilter(
                types=frozendict({EventTypes.Member: None}), include_others=True
            ),
        )

        self.assertEqual(is_all, False)
        self.assertDictEqual({}, state_dict)

        (state_dict, is_all,) = self.state_datastore._get_state_for_group_using_cache(
            self.state_datastore._state_group_members_cache,
            group,
            state_filter=StateFilter(
                types=frozendict({EventTypes.Member: None}), include_others=True
            ),
        )

        self.assertEqual(is_all, True)
        self.assertDictEqual(
            {
                (e3.type, e3.state_key): e3.event_id,
                (e5.type, e5.state_key): e5.event_id,
            },
            state_dict,
        )

        # test _get_state_for_group_using_cache correctly filters in members
        # with specific types
        (state_dict, is_all,) = self.state_datastore._get_state_for_group_using_cache(
            self.state_datastore._state_group_cache,
            group,
            state_filter=StateFilter(
                types=frozendict({EventTypes.Member: frozenset({e5.state_key})}),
                include_others=True,
            ),
        )

        self.assertEqual(is_all, False)
        self.assertDictEqual({}, state_dict)

        (state_dict, is_all,) = self.state_datastore._get_state_for_group_using_cache(
            self.state_datastore._state_group_members_cache,
            group,
            state_filter=StateFilter(
                types=frozendict({EventTypes.Member: frozenset({e5.state_key})}),
                include_others=True,
            ),
        )

        self.assertEqual(is_all, True)
        self.assertDictEqual({(e5.type, e5.state_key): e5.event_id}, state_dict)

        # test _get_state_for_group_using_cache correctly filters in members
        # with specific types
        (state_dict, is_all,) = self.state_datastore._get_state_for_group_using_cache(
            self.state_datastore._state_group_cache,
            group,
            state_filter=StateFilter(
                types=frozendict({EventTypes.Member: frozenset({e5.state_key})}),
                include_others=False,
            ),
        )

        self.assertEqual(is_all, False)
        self.assertDictEqual({}, state_dict)

        (state_dict, is_all,) = self.state_datastore._get_state_for_group_using_cache(
            self.state_datastore._state_group_members_cache,
            group,
            state_filter=StateFilter(
                types=frozendict({EventTypes.Member: frozenset({e5.state_key})}),
                include_others=False,
            ),
        )

        self.assertEqual(is_all, True)
        self.assertDictEqual({(e5.type, e5.state_key): e5.event_id}, state_dict)


class StateFilterDifferenceTestCase(TestCase):
    def assert_difference(
        self, minuend: StateFilter, subtrahend: StateFilter, expected: StateFilter
    ) -> None:
        self.assertEqual(
            minuend.approx_difference(subtrahend),
            expected,
            f"StateFilter difference not correct:\n\n\t{minuend!r}\nminus\n\t{subtrahend!r}\nwas\n\t{minuend.approx_difference(subtrahend)}\nexpected\n\t{expected}",
        )

    def test_state_filter_difference_no_include_other_minus_no_include_other(
        self,
    ) -> None:
        """
        Tests the StateFilter.approx_difference method
        where, in a.approx_difference(b), both a and b do not have the
        include_others flag set.
        """
        # (wildcard on state keys) - (wildcard on state keys):
        self.assert_difference(
            StateFilter.freeze(
                {EventTypes.Member: None, EventTypes.Create: None},
                include_others=False,
            ),
            StateFilter.freeze(
                {EventTypes.Member: None, EventTypes.CanonicalAlias: None},
                include_others=False,
            ),
            StateFilter.freeze({EventTypes.Create: None}, include_others=False),
        )

        # (wildcard on state keys) - (specific state keys)
        # This one is an over-approximation because we can't represent
        # 'all state keys except a few named examples'
        self.assert_difference(
            StateFilter.freeze({EventTypes.Member: None}, include_others=False),
            StateFilter.freeze(
                {EventTypes.Member: {"@wombat:spqr"}},
                include_others=False,
            ),
            StateFilter.freeze({EventTypes.Member: None}, include_others=False),
        )

        # (wildcard on state keys) - (no state keys)
        self.assert_difference(
            StateFilter.freeze(
                {EventTypes.Member: None},
                include_others=False,
            ),
            StateFilter.freeze(
                {
                    EventTypes.Member: set(),
                },
                include_others=False,
            ),
            StateFilter.freeze(
                {EventTypes.Member: None},
                include_others=False,
            ),
        )

        # (specific state keys) - (wildcard on state keys):
        self.assert_difference(
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr", "@spqr:spqr"},
                    EventTypes.CanonicalAlias: {""},
                },
                include_others=False,
            ),
            StateFilter.freeze(
                {EventTypes.Member: None},
                include_others=False,
            ),
            StateFilter.freeze(
                {EventTypes.CanonicalAlias: {""}},
                include_others=False,
            ),
        )

        # (specific state keys) - (specific state keys)
        self.assert_difference(
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr", "@spqr:spqr"},
                    EventTypes.CanonicalAlias: {""},
                },
                include_others=False,
            ),
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr"},
                },
                include_others=False,
            ),
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@spqr:spqr"},
                    EventTypes.CanonicalAlias: {""},
                },
                include_others=False,
            ),
        )

        # (specific state keys) - (no state keys)
        self.assert_difference(
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr", "@spqr:spqr"},
                    EventTypes.CanonicalAlias: {""},
                },
                include_others=False,
            ),
            StateFilter.freeze(
                {
                    EventTypes.Member: set(),
                },
                include_others=False,
            ),
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr", "@spqr:spqr"},
                    EventTypes.CanonicalAlias: {""},
                },
                include_others=False,
            ),
        )

    def test_state_filter_difference_include_other_minus_no_include_other(self) -> None:
        """
        Tests the StateFilter.approx_difference method
        where, in a.approx_difference(b), only a has the include_others flag set.
        """
        # (wildcard on state keys) - (wildcard on state keys):
        self.assert_difference(
            StateFilter.freeze(
                {EventTypes.Member: None, EventTypes.Create: None},
                include_others=True,
            ),
            StateFilter.freeze(
                {EventTypes.Member: None, EventTypes.CanonicalAlias: None},
                include_others=False,
            ),
            StateFilter.freeze(
                {
                    EventTypes.Create: None,
                    EventTypes.Member: set(),
                    EventTypes.CanonicalAlias: set(),
                },
                include_others=True,
            ),
        )

        # (wildcard on state keys) - (specific state keys)
        # This one is an over-approximation because we can't represent
        # 'all state keys except a few named examples'
        # This also shows that the resultant state filter is normalised.
        self.assert_difference(
            StateFilter.freeze({EventTypes.Member: None}, include_others=True),
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr"},
                    EventTypes.Create: {""},
                },
                include_others=False,
            ),
            StateFilter(types=frozendict(), include_others=True),
        )

        # (wildcard on state keys) - (no state keys)
        self.assert_difference(
            StateFilter.freeze(
                {EventTypes.Member: None},
                include_others=True,
            ),
            StateFilter.freeze(
                {
                    EventTypes.Member: set(),
                },
                include_others=False,
            ),
            StateFilter(
                types=frozendict(),
                include_others=True,
            ),
        )

        # (specific state keys) - (wildcard on state keys):
        self.assert_difference(
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr", "@spqr:spqr"},
                    EventTypes.CanonicalAlias: {""},
                },
                include_others=True,
            ),
            StateFilter.freeze(
                {EventTypes.Member: None},
                include_others=False,
            ),
            StateFilter.freeze(
                {
                    EventTypes.CanonicalAlias: {""},
                    EventTypes.Member: set(),
                },
                include_others=True,
            ),
        )

        # (specific state keys) - (specific state keys)
        self.assert_difference(
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr", "@spqr:spqr"},
                    EventTypes.CanonicalAlias: {""},
                },
                include_others=True,
            ),
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr"},
                },
                include_others=False,
            ),
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@spqr:spqr"},
                    EventTypes.CanonicalAlias: {""},
                },
                include_others=True,
            ),
        )

        # (specific state keys) - (no state keys)
        self.assert_difference(
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr", "@spqr:spqr"},
                    EventTypes.CanonicalAlias: {""},
                },
                include_others=True,
            ),
            StateFilter.freeze(
                {
                    EventTypes.Member: set(),
                },
                include_others=False,
            ),
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr", "@spqr:spqr"},
                    EventTypes.CanonicalAlias: {""},
                },
                include_others=True,
            ),
        )

    def test_state_filter_difference_include_other_minus_include_other(self) -> None:
        """
        Tests the StateFilter.approx_difference method
        where, in a.approx_difference(b), both a and b have the include_others
        flag set.
        """
        # (wildcard on state keys) - (wildcard on state keys):
        self.assert_difference(
            StateFilter.freeze(
                {EventTypes.Member: None, EventTypes.Create: None},
                include_others=True,
            ),
            StateFilter.freeze(
                {EventTypes.Member: None, EventTypes.CanonicalAlias: None},
                include_others=True,
            ),
            StateFilter(types=frozendict(), include_others=False),
        )

        # (wildcard on state keys) - (specific state keys)
        # This one is an over-approximation because we can't represent
        # 'all state keys except a few named examples'
        self.assert_difference(
            StateFilter.freeze({EventTypes.Member: None}, include_others=True),
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr"},
                    EventTypes.CanonicalAlias: {""},
                },
                include_others=True,
            ),
            StateFilter.freeze(
                {EventTypes.Member: None, EventTypes.CanonicalAlias: None},
                include_others=False,
            ),
        )

        # (wildcard on state keys) - (no state keys)
        self.assert_difference(
            StateFilter.freeze(
                {EventTypes.Member: None},
                include_others=True,
            ),
            StateFilter.freeze(
                {
                    EventTypes.Member: set(),
                },
                include_others=True,
            ),
            StateFilter.freeze(
                {EventTypes.Member: None},
                include_others=False,
            ),
        )

        # (specific state keys) - (wildcard on state keys):
        self.assert_difference(
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr", "@spqr:spqr"},
                    EventTypes.CanonicalAlias: {""},
                },
                include_others=True,
            ),
            StateFilter.freeze(
                {EventTypes.Member: None},
                include_others=True,
            ),
            StateFilter(
                types=frozendict(),
                include_others=False,
            ),
        )

        # (specific state keys) - (specific state keys)
        # This one is an over-approximation because we can't represent
        # 'all state keys except a few named examples'
        self.assert_difference(
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr", "@spqr:spqr"},
                    EventTypes.CanonicalAlias: {""},
                    EventTypes.Create: {""},
                },
                include_others=True,
            ),
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr"},
                    EventTypes.Create: set(),
                },
                include_others=True,
            ),
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@spqr:spqr"},
                    EventTypes.Create: {""},
                },
                include_others=False,
            ),
        )

        # (specific state keys) - (no state keys)
        self.assert_difference(
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr", "@spqr:spqr"},
                    EventTypes.CanonicalAlias: {""},
                },
                include_others=True,
            ),
            StateFilter.freeze(
                {
                    EventTypes.Member: set(),
                },
                include_others=True,
            ),
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr", "@spqr:spqr"},
                },
                include_others=False,
            ),
        )

    def test_state_filter_difference_no_include_other_minus_include_other(self) -> None:
        """
        Tests the StateFilter.approx_difference method
        where, in a.approx_difference(b), only b has the include_others flag set.
        """
        # (wildcard on state keys) - (wildcard on state keys):
        self.assert_difference(
            StateFilter.freeze(
                {EventTypes.Member: None, EventTypes.Create: None},
                include_others=False,
            ),
            StateFilter.freeze(
                {EventTypes.Member: None, EventTypes.CanonicalAlias: None},
                include_others=True,
            ),
            StateFilter(types=frozendict(), include_others=False),
        )

        # (wildcard on state keys) - (specific state keys)
        # This one is an over-approximation because we can't represent
        # 'all state keys except a few named examples'
        self.assert_difference(
            StateFilter.freeze({EventTypes.Member: None}, include_others=False),
            StateFilter.freeze(
                {EventTypes.Member: {"@wombat:spqr"}},
                include_others=True,
            ),
            StateFilter.freeze({EventTypes.Member: None}, include_others=False),
        )

        # (wildcard on state keys) - (no state keys)
        self.assert_difference(
            StateFilter.freeze(
                {EventTypes.Member: None},
                include_others=False,
            ),
            StateFilter.freeze(
                {
                    EventTypes.Member: set(),
                },
                include_others=True,
            ),
            StateFilter.freeze(
                {EventTypes.Member: None},
                include_others=False,
            ),
        )

        # (specific state keys) - (wildcard on state keys):
        self.assert_difference(
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr", "@spqr:spqr"},
                    EventTypes.CanonicalAlias: {""},
                },
                include_others=False,
            ),
            StateFilter.freeze(
                {EventTypes.Member: None},
                include_others=True,
            ),
            StateFilter(
                types=frozendict(),
                include_others=False,
            ),
        )

        # (specific state keys) - (specific state keys)
        # This one is an over-approximation because we can't represent
        # 'all state keys except a few named examples'
        self.assert_difference(
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr", "@spqr:spqr"},
                    EventTypes.CanonicalAlias: {""},
                },
                include_others=False,
            ),
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr"},
                },
                include_others=True,
            ),
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@spqr:spqr"},
                },
                include_others=False,
            ),
        )

        # (specific state keys) - (no state keys)
        self.assert_difference(
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr", "@spqr:spqr"},
                    EventTypes.CanonicalAlias: {""},
                },
                include_others=False,
            ),
            StateFilter.freeze(
                {
                    EventTypes.Member: set(),
                },
                include_others=True,
            ),
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:spqr", "@spqr:spqr"},
                },
                include_others=False,
            ),
        )

    def test_state_filter_difference_simple_cases(self) -> None:
        """
        Tests some very simple cases of the StateFilter approx_difference,
        that are not explicitly tested by the more in-depth tests.
        """

        self.assert_difference(StateFilter.all(), StateFilter.all(), StateFilter.none())

        self.assert_difference(
            StateFilter.all(),
            StateFilter.none(),
            StateFilter.all(),
        )


class StateFilterTestCase(TestCase):
    def test_return_expanded(self) -> None:
        """
        Tests the behaviour of the return_expanded() function that expands
        StateFilters to include more state types (for the sake of cache hit rate).
        """

        self.assertEqual(StateFilter.all().return_expanded(), StateFilter.all())

        self.assertEqual(StateFilter.none().return_expanded(), StateFilter.none())

        # Concrete-only state filters stay the same
        # (Case: mixed filter)
        self.assertEqual(
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:test", "@alicia:test"},
                    "some.other.state.type": {""},
                },
                include_others=False,
            ).return_expanded(),
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:test", "@alicia:test"},
                    "some.other.state.type": {""},
                },
                include_others=False,
            ),
        )

        # Concrete-only state filters stay the same
        # (Case: non-member-only filter)
        self.assertEqual(
            StateFilter.freeze(
                {"some.other.state.type": {""}}, include_others=False
            ).return_expanded(),
            StateFilter.freeze({"some.other.state.type": {""}}, include_others=False),
        )

        # Concrete-only state filters stay the same
        # (Case: member-only filter)
        self.assertEqual(
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:test", "@alicia:test"},
                },
                include_others=False,
            ).return_expanded(),
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:test", "@alicia:test"},
                },
                include_others=False,
            ),
        )

        # Wildcard member-only state filters stay the same
        self.assertEqual(
            StateFilter.freeze(
                {EventTypes.Member: None},
                include_others=False,
            ).return_expanded(),
            StateFilter.freeze(
                {EventTypes.Member: None},
                include_others=False,
            ),
        )

        # If there is a wildcard in the non-member portion of the filter,
        # it's expanded to include ALL non-member events.
        # (Case: mixed filter)
        self.assertEqual(
            StateFilter.freeze(
                {
                    EventTypes.Member: {"@wombat:test", "@alicia:test"},
                    "some.other.state.type": None,
                },
                include_others=False,
            ).return_expanded(),
            StateFilter.freeze(
                {EventTypes.Member: {"@wombat:test", "@alicia:test"}},
                include_others=True,
            ),
        )

        # If there is a wildcard in the non-member portion of the filter,
        # it's expanded to include ALL non-member events.
        # (Case: non-member-only filter)
        self.assertEqual(
            StateFilter.freeze(
                {
                    "some.other.state.type": None,
                },
                include_others=False,
            ).return_expanded(),
            StateFilter.freeze({EventTypes.Member: set()}, include_others=True),
        )
        self.assertEqual(
            StateFilter.freeze(
                {
                    "some.other.state.type": None,
                    "yet.another.state.type": {"wombat"},
                },
                include_others=False,
            ).return_expanded(),
            StateFilter.freeze({EventTypes.Member: set()}, include_others=True),
        )