diff --git a/changelog.d/14646.misc b/changelog.d/14646.misc
new file mode 100644
index 000000000000..d44571b73149
--- /dev/null
+++ b/changelog.d/14646.misc
@@ -0,0 +1 @@
+Add missing type hints.
diff --git a/mypy.ini b/mypy.ini
index c3fbd1a95559..a4a1e4511a07 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -88,6 +88,9 @@ disallow_untyped_defs = False
 [mypy-tests.*]
 disallow_untyped_defs = False
 
+[mypy-tests.handlers.test_sso]
+disallow_untyped_defs = True
+
 [mypy-tests.handlers.test_user_directory]
 disallow_untyped_defs = True
 
@@ -103,16 +106,7 @@ disallow_untyped_defs = True
 [mypy-tests.state.test_profile]
 disallow_untyped_defs = True
 
-[mypy-tests.storage.test_id_generators]
-disallow_untyped_defs = True
-
-[mypy-tests.storage.test_profile]
-disallow_untyped_defs = True
-
-[mypy-tests.handlers.test_sso]
-disallow_untyped_defs = True
-
-[mypy-tests.storage.test_user_directory]
+[mypy-tests.storage.*]
 disallow_untyped_defs = True
 
 [mypy-tests.rest.*]
diff --git a/synapse/storage/databases/main/end_to_end_keys.py b/synapse/storage/databases/main/end_to_end_keys.py
index 643c47d608da..4c691642e2b5 100644
--- a/synapse/storage/databases/main/end_to_end_keys.py
+++ b/synapse/storage/databases/main/end_to_end_keys.py
@@ -140,7 +140,7 @@ async def get_e2e_device_keys_for_federation_query(
     @cancellable
     async def get_e2e_device_keys_for_cs_api(
         self,
-        query_list: List[Tuple[str, Optional[str]]],
+        query_list: Collection[Tuple[str, Optional[str]]],
         include_displaynames: bool = True,
     ) -> Dict[str, Dict[str, JsonDict]]:
         """Fetch a list of device keys, formatted suitably for the C/S API.
diff --git a/tests/storage/databases/main/test_deviceinbox.py b/tests/storage/databases/main/test_deviceinbox.py
index 50c20c5b921a..373707b275c7 100644
--- a/tests/storage/databases/main/test_deviceinbox.py
+++ b/tests/storage/databases/main/test_deviceinbox.py
@@ -12,8 +12,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from twisted.test.proto_helpers import MemoryReactor
+
 from synapse.rest import admin
 from synapse.rest.client import devices
+from synapse.server import HomeServer
+from synapse.util import Clock
 
 from tests.unittest import HomeserverTestCase
 
@@ -25,11 +29,11 @@ class DeviceInboxBackgroundUpdateStoreTestCase(HomeserverTestCase):
         devices.register_servlets,
     ]
 
-    def prepare(self, reactor, clock, hs):
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         self.store = hs.get_datastores().main
         self.user_id = self.register_user("foo", "pass")
 
-    def test_background_remove_deleted_devices_from_device_inbox(self):
+    def test_background_remove_deleted_devices_from_device_inbox(self) -> None:
         """Test that the background task to delete old device_inboxes works properly."""
 
         # create a valid device
@@ -89,7 +93,7 @@ def test_background_remove_deleted_devices_from_device_inbox(self):
         self.assertEqual(1, len(res))
         self.assertEqual(res[0], "cur_device")
 
-    def test_background_remove_hidden_devices_from_device_inbox(self):
+    def test_background_remove_hidden_devices_from_device_inbox(self) -> None:
         """Test that the background task to delete hidden devices
         from device_inboxes works properly."""
 
diff --git a/tests/storage/databases/main/test_events_worker.py b/tests/storage/databases/main/test_events_worker.py
index 5773172ab890..9f33afcca04d 100644
--- a/tests/storage/databases/main/test_events_worker.py
+++ b/tests/storage/databases/main/test_events_worker.py
@@ -45,7 +45,7 @@ class HaveSeenEventsTestCase(unittest.HomeserverTestCase):
         login.register_servlets,
     ]
 
-    def prepare(self, reactor, clock, hs):
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         self.hs = hs
         self.store: EventsWorkerStore = hs.get_datastores().main
 
@@ -68,7 +68,7 @@ def prepare(self, reactor, clock, hs):
 
             self.event_ids.append(event.event_id)
 
-    def test_simple(self):
+    def test_simple(self) -> None:
         with LoggingContext(name="test") as ctx:
             res = self.get_success(
                 self.store.have_seen_events(
@@ -90,7 +90,7 @@ def test_simple(self):
             self.assertEqual(res, {self.event_ids[0]})
             self.assertEqual(ctx.get_resource_usage().db_txn_count, 0)
 
-    def test_persisting_event_invalidates_cache(self):
+    def test_persisting_event_invalidates_cache(self) -> None:
         """
         Test to make sure that the `have_seen_event` cache
         is invalidated after we persist an event and returns
@@ -138,7 +138,7 @@ def test_persisting_event_invalidates_cache(self):
             # That should result in a single db query to lookup
             self.assertEqual(ctx.get_resource_usage().db_txn_count, 1)
 
-    def test_invalidate_cache_by_room_id(self):
+    def test_invalidate_cache_by_room_id(self) -> None:
         """
         Test to make sure that all events associated with the given `(room_id,)`
         are invalidated in the `have_seen_event` cache.
@@ -175,7 +175,7 @@ class EventCacheTestCase(unittest.HomeserverTestCase):
         login.register_servlets,
     ]
 
-    def prepare(self, reactor, clock, hs):
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         self.store: EventsWorkerStore = hs.get_datastores().main
 
         self.user = self.register_user("user", "pass")
@@ -189,7 +189,7 @@ def prepare(self, reactor, clock, hs):
         # Reset the event cache so the tests start with it empty
         self.get_success(self.store._get_event_cache.clear())
 
-    def test_simple(self):
+    def test_simple(self) -> None:
         """Test that we cache events that we pull from the DB."""
 
         with LoggingContext("test") as ctx:
@@ -198,7 +198,7 @@ def test_simple(self):
             # We should have fetched the event from the DB
             self.assertEqual(ctx.get_resource_usage().evt_db_fetch_count, 1)
 
-    def test_event_ref(self):
+    def test_event_ref(self) -> None:
         """Test that we reuse events that are still in memory but have fallen
         out of the cache, rather than requesting them from the DB.
         """
@@ -223,7 +223,7 @@ def test_event_ref(self):
             # from the DB
             self.assertEqual(ctx.get_resource_usage().evt_db_fetch_count, 0)
 
-    def test_dedupe(self):
+    def test_dedupe(self) -> None:
         """Test that if we request the same event multiple times we only pull it
         out once.
         """
@@ -241,7 +241,7 @@ def test_dedupe(self):
 class DatabaseOutageTestCase(unittest.HomeserverTestCase):
     """Test event fetching during a database outage."""
 
-    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer):
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         self.store: EventsWorkerStore = hs.get_datastores().main
 
         self.room_id = f"!room:{hs.hostname}"
@@ -377,7 +377,7 @@ class GetEventCancellationTestCase(unittest.HomeserverTestCase):
         login.register_servlets,
     ]
 
-    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer):
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         self.store: EventsWorkerStore = hs.get_datastores().main
 
         self.user = self.register_user("user", "pass")
@@ -412,7 +412,8 @@ def blocking_get_event_calls(
         unblock: "Deferred[None]" = Deferred()
         original_runWithConnection = self.store.db_pool.runWithConnection
 
-        async def runWithConnection(*args, **kwargs):
+        # Don't bother with the types here, we just pass into the original function.
+        async def runWithConnection(*args, **kwargs):  # type: ignore[no-untyped-def]
             await unblock
             return await original_runWithConnection(*args, **kwargs)
 
@@ -441,7 +442,7 @@ async def get_event(ctx: LoggingContext) -> None:
         self.assertEqual(ctx1.get_resource_usage().evt_db_fetch_count, 1)
         self.assertEqual(ctx2.get_resource_usage().evt_db_fetch_count, 0)
 
-    def test_first_get_event_cancelled(self):
+    def test_first_get_event_cancelled(self) -> None:
         """Test cancellation of the first `get_event` call sharing a database fetch.
 
         The first `get_event` call is the one which initiates the fetch. We expect the
@@ -467,7 +468,7 @@ def test_first_get_event_cancelled(self):
             # The second `get_event` call should complete successfully.
             self.get_success(get_event2)
 
-    def test_second_get_event_cancelled(self):
+    def test_second_get_event_cancelled(self) -> None:
         """Test cancellation of the second `get_event` call sharing a database fetch."""
         with self.blocking_get_event_calls() as (unblock, get_event1, get_event2):
             # Cancel the second `get_event` call.
diff --git a/tests/storage/databases/main/test_lock.py b/tests/storage/databases/main/test_lock.py
index 3cc2a58d8d42..56cb49d9b58a 100644
--- a/tests/storage/databases/main/test_lock.py
+++ b/tests/storage/databases/main/test_lock.py
@@ -15,18 +15,20 @@
 from twisted.internet import defer, reactor
 from twisted.internet.base import ReactorBase
 from twisted.internet.defer import Deferred
+from twisted.test.proto_helpers import MemoryReactor
 
 from synapse.server import HomeServer
 from synapse.storage.databases.main.lock import _LOCK_TIMEOUT_MS
+from synapse.util import Clock
 
 from tests import unittest
 
 
 class LockTestCase(unittest.HomeserverTestCase):
-    def prepare(self, reactor, clock, hs: HomeServer):
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         self.store = hs.get_datastores().main
 
-    def test_acquire_contention(self):
+    def test_acquire_contention(self) -> None:
         # Track the number of tasks holding the lock.
         # Should be at most 1.
         in_lock = 0
@@ -34,7 +36,7 @@ def test_acquire_contention(self):
 
         release_lock: "Deferred[None]" = Deferred()
 
-        async def task():
+        async def task() -> None:
             nonlocal in_lock
             nonlocal max_in_lock
 
@@ -76,7 +78,7 @@ async def task():
         # At most one task should have held the lock at a time.
         self.assertEqual(max_in_lock, 1)
 
-    def test_simple_lock(self):
+    def test_simple_lock(self) -> None:
         """Test that we can take out a lock and that while we hold it nobody
         else can take it out.
         """
@@ -103,7 +105,7 @@ def test_simple_lock(self):
         self.get_success(lock3.__aenter__())
         self.get_success(lock3.__aexit__(None, None, None))
 
-    def test_maintain_lock(self):
+    def test_maintain_lock(self) -> None:
         """Test that we don't time out locks while they're still active"""
 
         lock = self.get_success(self.store.try_acquire_lock("name", "key"))
@@ -119,7 +121,7 @@ def test_maintain_lock(self):
 
         self.get_success(lock.__aexit__(None, None, None))
 
-    def test_timeout_lock(self):
+    def test_timeout_lock(self) -> None:
         """Test that we time out locks if they're not updated for ages"""
 
         lock = self.get_success(self.store.try_acquire_lock("name", "key"))
@@ -139,7 +141,7 @@ def test_timeout_lock(self):
 
         self.assertFalse(self.get_success(lock.is_still_valid()))
 
-    def test_drop(self):
+    def test_drop(self) -> None:
         """Test that dropping the context manager means we stop renewing the lock"""
 
         lock = self.get_success(self.store.try_acquire_lock("name", "key"))
@@ -153,7 +155,7 @@ def test_drop(self):
         lock2 = self.get_success(self.store.try_acquire_lock("name", "key"))
         self.assertIsNotNone(lock2)
 
-    def test_shutdown(self):
+    def test_shutdown(self) -> None:
         """Test that shutting down Synapse releases the locks"""
         # Acquire two locks
         lock = self.get_success(self.store.try_acquire_lock("name", "key1"))
diff --git a/tests/storage/databases/main/test_receipts.py b/tests/storage/databases/main/test_receipts.py
index c4f12d81d73a..68026e283046 100644
--- a/tests/storage/databases/main/test_receipts.py
+++ b/tests/storage/databases/main/test_receipts.py
@@ -33,7 +33,7 @@ class ReceiptsBackgroundUpdateStoreTestCase(HomeserverTestCase):
         login.register_servlets,
     ]
 
-    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer):
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         self.store = hs.get_datastores().main
         self.user_id = self.register_user("foo", "pass")
         self.token = self.login("foo", "pass")
@@ -47,7 +47,7 @@ def _test_background_receipts_unique_index(
         table: str,
         receipts: Dict[Tuple[str, str, str], Sequence[Dict[str, Any]]],
         expected_unique_receipts: Dict[Tuple[str, str, str], Optional[Dict[str, Any]]],
-    ):
+    ) -> None:
         """Test that the background update to uniqueify non-thread receipts in
         the given receipts table works properly.
 
@@ -154,7 +154,7 @@ def drop_receipts_unique_index(txn: LoggingTransaction) -> None:
                     f"Background update did not remove all duplicate receipts from {table}",
                 )
 
-    def test_background_receipts_linearized_unique_index(self):
+    def test_background_receipts_linearized_unique_index(self) -> None:
         """Test that the background update to uniqueify non-thread receipts in
         `receipts_linearized` works properly.
         """
@@ -177,7 +177,7 @@ def test_background_receipts_linearized_unique_index(self):
             },
         )
 
-    def test_background_receipts_graph_unique_index(self):
+    def test_background_receipts_graph_unique_index(self) -> None:
         """Test that the background update to uniqueify non-thread receipts in
         `receipts_graph` works properly.
         """
diff --git a/tests/storage/databases/main/test_room.py b/tests/storage/databases/main/test_room.py
index 1edb61963026..7d961fac649c 100644
--- a/tests/storage/databases/main/test_room.py
+++ b/tests/storage/databases/main/test_room.py
@@ -14,10 +14,14 @@
 
 import json
 
+from twisted.test.proto_helpers import MemoryReactor
+
 from synapse.api.constants import RoomTypes
 from synapse.rest import admin
 from synapse.rest.client import login, room
+from synapse.server import HomeServer
 from synapse.storage.databases.main.room import _BackgroundUpdates
+from synapse.util import Clock
 
 from tests.unittest import HomeserverTestCase
 
@@ -30,7 +34,7 @@ class RoomBackgroundUpdateStoreTestCase(HomeserverTestCase):
         login.register_servlets,
     ]
 
-    def prepare(self, reactor, clock, hs):
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         self.store = hs.get_datastores().main
         self.user_id = self.register_user("foo", "pass")
         self.token = self.login("foo", "pass")
@@ -40,7 +44,7 @@ def _generate_room(self) -> str:
 
         return room_id
 
-    def test_background_populate_rooms_creator_column(self):
+    def test_background_populate_rooms_creator_column(self) -> None:
         """Test that the background update to populate the rooms creator column
         works properly.
         """
@@ -95,7 +99,7 @@ def test_background_populate_rooms_creator_column(self):
         )
         self.assertEqual(room_creator_after, self.user_id)
 
-    def test_background_add_room_type_column(self):
+    def test_background_add_room_type_column(self) -> None:
         """Test that the background update to populate the `room_type` column in
         `room_stats_state` works properly.
         """
diff --git a/tests/storage/test__base.py b/tests/storage/test__base.py
index 09cb06d614a1..8bbf936ae9d7 100644
--- a/tests/storage/test__base.py
+++ b/tests/storage/test__base.py
@@ -106,7 +106,7 @@ def test_upsert_many(self) -> None:
             {(1, "user1", "hello"), (2, "user2", "bleb")},
         )
 
-    def test_simple_update_many(self):
+    def test_simple_update_many(self) -> None:
         """
         simple_update_many performs many updates at once.
         """
diff --git a/tests/storage/test_account_data.py b/tests/storage/test_account_data.py
index 72bf5b3d311c..1bfd11ceae4f 100644
--- a/tests/storage/test_account_data.py
+++ b/tests/storage/test_account_data.py
@@ -14,13 +14,17 @@
 
 from typing import Iterable, Optional, Set
 
+from twisted.test.proto_helpers import MemoryReactor
+
 from synapse.api.constants import AccountDataTypes
+from synapse.server import HomeServer
+from synapse.util import Clock
 
 from tests import unittest
 
 
 class IgnoredUsersTestCase(unittest.HomeserverTestCase):
-    def prepare(self, hs, reactor, clock):
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         self.store = self.hs.get_datastores().main
         self.user = "@user:test"
 
@@ -55,7 +59,7 @@ def assert_ignored(
             expected_ignored_user_ids,
         )
 
-    def test_ignoring_users(self):
+    def test_ignoring_users(self) -> None:
         """Basic adding/removing of users from the ignore list."""
         self._update_ignore_list("@other:test", "@another:remote")
         self.assert_ignored(self.user, {"@other:test", "@another:remote"})
@@ -82,7 +86,7 @@ def test_ignoring_users(self):
         # Check the removed user.
         self.assert_ignorers("@another:remote", {self.user})
 
-    def test_caching(self):
+    def test_caching(self) -> None:
         """Ensure that caching works properly between different users."""
         # The first user ignores a user.
         self._update_ignore_list("@other:test")
@@ -99,7 +103,7 @@ def test_caching(self):
         self.assert_ignored(self.user, set())
         self.assert_ignorers("@other:test", {"@second:test"})
 
-    def test_invalid_data(self):
+    def test_invalid_data(self) -> None:
         """Invalid data ends up clearing out the ignored users list."""
         # Add some data and ensure it is there.
         self._update_ignore_list("@other:test")
diff --git a/tests/storage/test_appservice.py b/tests/storage/test_appservice.py
index 1047ed09c85d..5e1324a16908 100644
--- a/tests/storage/test_appservice.py
+++ b/tests/storage/test_appservice.py
@@ -26,7 +26,7 @@
 from synapse.config._base import ConfigError
 from synapse.events import EventBase
 from synapse.server import HomeServer
-from synapse.storage.database import DatabasePool, make_conn
+from synapse.storage.database import DatabasePool, LoggingDatabaseConnection, make_conn
 from synapse.storage.databases.main.appservice import (
     ApplicationServiceStore,
     ApplicationServiceTransactionStore,
@@ -39,7 +39,7 @@
 
 
 class ApplicationServiceStoreTestCase(unittest.HomeserverTestCase):
-    def setUp(self):
+    def setUp(self) -> None:
         super(ApplicationServiceStoreTestCase, self).setUp()
 
         self.as_yaml_files: List[str] = []
@@ -73,7 +73,9 @@ def tearDown(self) -> None:
 
         super(ApplicationServiceStoreTestCase, self).tearDown()
 
-    def _add_appservice(self, as_token, id, url, hs_token, sender) -> None:
+    def _add_appservice(
+        self, as_token: str, id: str, url: str, hs_token: str, sender: str
+    ) -> None:
         as_yaml = {
             "url": url,
             "as_token": as_token,
@@ -135,7 +137,7 @@ def setUp(self) -> None:
             database, make_conn(db_config, self.engine, "test"), self.hs
         )
 
-    def _add_service(self, url, as_token, id) -> None:
+    def _add_service(self, url: str, as_token: str, id: str) -> None:
         as_yaml = {
             "url": url,
             "as_token": as_token,
@@ -149,7 +151,7 @@ def _add_service(self, url, as_token, id) -> None:
             outfile.write(yaml.dump(as_yaml))
             self.as_yaml_files.append(as_token)
 
-    def _set_state(self, id: str, state: ApplicationServiceState):
+    def _set_state(self, id: str, state: ApplicationServiceState) -> defer.Deferred:
         return self.db_pool.runOperation(
             self.engine.convert_param_style(
                 "INSERT INTO application_services_state(as_id, state) VALUES(?,?)"
@@ -157,7 +159,9 @@ def _set_state(self, id: str, state: ApplicationServiceState):
             (id, state.value),
         )
 
-    def _insert_txn(self, as_id, txn_id, events):
+    def _insert_txn(
+        self, as_id: str, txn_id: int, events: List[Mock]
+    ) -> "defer.Deferred[None]":
         return self.db_pool.runOperation(
             self.engine.convert_param_style(
                 "INSERT INTO application_services_txns(as_id, txn_id, event_ids) "
@@ -448,12 +452,14 @@ def test_set_appservice_stream_type_pos_invalid_type(self) -> None:
 
 # required for ApplicationServiceTransactionStoreTestCase tests
 class TestTransactionStore(ApplicationServiceTransactionStore, ApplicationServiceStore):
-    def __init__(self, database: DatabasePool, db_conn, hs) -> None:
+    def __init__(
+        self, database: DatabasePool, db_conn: LoggingDatabaseConnection, hs: HomeServer
+    ) -> None:
         super().__init__(database, db_conn, hs)
 
 
 class ApplicationServiceStoreConfigTestCase(unittest.HomeserverTestCase):
-    def _write_config(self, suffix, **kwargs) -> str:
+    def _write_config(self, suffix: str, **kwargs: str) -> str:
         vals = {
             "id": "id" + suffix,
             "url": "url" + suffix,
diff --git a/tests/storage/test_base.py b/tests/storage/test_base.py
index 40e58f8199d0..256d28e4c99a 100644
--- a/tests/storage/test_base.py
+++ b/tests/storage/test_base.py
@@ -12,8 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-
 from collections import OrderedDict
+from typing import Generator
 from unittest.mock import Mock
 
 from twisted.internet import defer
@@ -30,7 +30,7 @@
 class SQLBaseStoreTestCase(unittest.TestCase):
     """Test the "simple" SQL generating methods in SQLBaseStore."""
 
-    def setUp(self):
+    def setUp(self) -> None:
         self.db_pool = Mock(spec=["runInteraction"])
         self.mock_txn = Mock()
         self.mock_conn = Mock(spec_set=["cursor", "rollback", "commit"])
@@ -38,12 +38,12 @@ def setUp(self):
         self.mock_conn.rollback.return_value = None
         # Our fake runInteraction just runs synchronously inline
 
-        def runInteraction(func, *args, **kwargs):
+        def runInteraction(func, *args, **kwargs) -> defer.Deferred:  # type: ignore[no-untyped-def]
             return defer.succeed(func(self.mock_txn, *args, **kwargs))
 
         self.db_pool.runInteraction = runInteraction
 
-        def runWithConnection(func, *args, **kwargs):
+        def runWithConnection(func, *args, **kwargs):  # type: ignore[no-untyped-def]
             return defer.succeed(func(self.mock_conn, *args, **kwargs))
 
         self.db_pool.runWithConnection = runWithConnection
@@ -62,7 +62,7 @@ def runWithConnection(func, *args, **kwargs):
         self.datastore = SQLBaseStore(db, None, hs)  # type: ignore[arg-type]
 
     @defer.inlineCallbacks
-    def test_insert_1col(self):
+    def test_insert_1col(self) -> Generator["defer.Deferred[object]", object, None]:
         self.mock_txn.rowcount = 1
 
         yield defer.ensureDeferred(
@@ -76,7 +76,7 @@ def test_insert_1col(self):
         )
 
     @defer.inlineCallbacks
-    def test_insert_3cols(self):
+    def test_insert_3cols(self) -> Generator["defer.Deferred[object]", object, None]:
         self.mock_txn.rowcount = 1
 
         yield defer.ensureDeferred(
@@ -92,7 +92,7 @@ def test_insert_3cols(self):
         )
 
     @defer.inlineCallbacks
-    def test_select_one_1col(self):
+    def test_select_one_1col(self) -> Generator["defer.Deferred[object]", object, None]:
         self.mock_txn.rowcount = 1
         self.mock_txn.__iter__ = Mock(return_value=iter([("Value",)]))
 
@@ -108,7 +108,7 @@ def test_select_one_1col(self):
         )
 
     @defer.inlineCallbacks
-    def test_select_one_3col(self):
+    def test_select_one_3col(self) -> Generator["defer.Deferred[object]", object, None]:
         self.mock_txn.rowcount = 1
         self.mock_txn.fetchone.return_value = (1, 2, 3)
 
@@ -126,7 +126,9 @@ def test_select_one_3col(self):
         )
 
     @defer.inlineCallbacks
-    def test_select_one_missing(self):
+    def test_select_one_missing(
+        self,
+    ) -> Generator["defer.Deferred[object]", object, None]:
         self.mock_txn.rowcount = 0
         self.mock_txn.fetchone.return_value = None
 
@@ -142,7 +144,7 @@ def test_select_one_missing(self):
         self.assertFalse(ret)
 
     @defer.inlineCallbacks
-    def test_select_list(self):
+    def test_select_list(self) -> Generator["defer.Deferred[object]", object, None]:
         self.mock_txn.rowcount = 3
         self.mock_txn.__iter__ = Mock(return_value=iter([(1,), (2,), (3,)]))
         self.mock_txn.description = (("colA", None, None, None, None, None, None),)
@@ -159,7 +161,7 @@ def test_select_list(self):
         )
 
     @defer.inlineCallbacks
-    def test_update_one_1col(self):
+    def test_update_one_1col(self) -> Generator["defer.Deferred[object]", object, None]:
         self.mock_txn.rowcount = 1
 
         yield defer.ensureDeferred(
@@ -176,7 +178,9 @@ def test_update_one_1col(self):
         )
 
     @defer.inlineCallbacks
-    def test_update_one_4cols(self):
+    def test_update_one_4cols(
+        self,
+    ) -> Generator["defer.Deferred[object]", object, None]:
         self.mock_txn.rowcount = 1
 
         yield defer.ensureDeferred(
@@ -193,7 +197,7 @@ def test_update_one_4cols(self):
         )
 
     @defer.inlineCallbacks
-    def test_delete_one(self):
+    def test_delete_one(self) -> Generator["defer.Deferred[object]", object, None]:
         self.mock_txn.rowcount = 1
 
         yield defer.ensureDeferred(
diff --git a/tests/storage/test_cleanup_extrems.py b/tests/storage/test_cleanup_extrems.py
index b998ad42d90f..d570684c9926 100644
--- a/tests/storage/test_cleanup_extrems.py
+++ b/tests/storage/test_cleanup_extrems.py
@@ -15,11 +15,16 @@
 import os.path
 from unittest.mock import Mock, patch
 
+from twisted.test.proto_helpers import MemoryReactor
+
 import synapse.rest.admin
 from synapse.api.constants import EventTypes
 from synapse.rest.client import login, room
+from synapse.server import HomeServer
 from synapse.storage import prepare_database
+from synapse.storage.types import Cursor
 from synapse.types import UserID, create_requester
+from synapse.util import Clock
 
 from tests.unittest import HomeserverTestCase
 
@@ -29,7 +34,9 @@ class CleanupExtremBackgroundUpdateStoreTestCase(HomeserverTestCase):
     Test the background update to clean forward extremities table.
     """
 
-    def prepare(self, reactor, clock, homeserver):
+    def prepare(
+        self, reactor: MemoryReactor, clock: Clock, homeserver: HomeServer
+    ) -> None:
         self.store = homeserver.get_datastores().main
         self.room_creator = homeserver.get_room_creation_handler()
 
@@ -39,7 +46,7 @@ def prepare(self, reactor, clock, homeserver):
         info, _ = self.get_success(self.room_creator.create_room(self.requester, {}))
         self.room_id = info["room_id"]
 
-    def run_background_update(self):
+    def run_background_update(self) -> None:
         """Re run the background update to clean up the extremities."""
         # Make sure we don't clash with in progress updates.
         self.assertTrue(
@@ -54,7 +61,7 @@ def run_background_update(self):
             "delete_forward_extremities.sql",
         )
 
-        def run_delta_file(txn):
+        def run_delta_file(txn: Cursor) -> None:
             prepare_database.executescript(txn, schema_path)
 
         self.get_success(
@@ -84,7 +91,7 @@ def add_extremity(self, room_id: str, event_id: str) -> None:
             (room_id,)
         )
 
-    def test_soft_failed_extremities_handled_correctly(self):
+    def test_soft_failed_extremities_handled_correctly(self) -> None:
         """Test that extremities are correctly calculated in the presence of
         soft failed events.
 
@@ -114,7 +121,7 @@ def test_soft_failed_extremities_handled_correctly(self):
 
         self.assertEqual(latest_event_ids, [event_id_4])
 
-    def test_basic_cleanup(self):
+    def test_basic_cleanup(self) -> None:
         """Test that extremities are correctly calculated in the presence of
         soft failed events.
 
@@ -149,7 +156,7 @@ def test_basic_cleanup(self):
         )
         self.assertEqual(latest_event_ids, [event_id_b])
 
-    def test_chain_of_fail_cleanup(self):
+    def test_chain_of_fail_cleanup(self) -> None:
         """Test that extremities are correctly calculated in the presence of
         soft failed events.
 
@@ -187,7 +194,7 @@ def test_chain_of_fail_cleanup(self):
         )
         self.assertEqual(latest_event_ids, [event_id_b])
 
-    def test_forked_graph_cleanup(self):
+    def test_forked_graph_cleanup(self) -> None:
         r"""Test that extremities are correctly calculated in the presence of
         soft failed events.
 
@@ -252,12 +259,14 @@ class CleanupExtremDummyEventsTestCase(HomeserverTestCase):
         room.register_servlets,
     ]
 
-    def make_homeserver(self, reactor, clock):
+    def make_homeserver(self, reactor: MemoryReactor, clock: Clock) -> HomeServer:
         config = self.default_config()
         config["cleanup_extremities_with_dummy_events"] = True
         return self.setup_test_homeserver(config=config)
 
-    def prepare(self, reactor, clock, homeserver):
+    def prepare(
+        self, reactor: MemoryReactor, clock: Clock, homeserver: HomeServer
+    ) -> None:
         self.store = homeserver.get_datastores().main
         self.room_creator = homeserver.get_room_creation_handler()
         self.event_creator_handler = homeserver.get_event_creation_handler()
@@ -273,7 +282,7 @@ def prepare(self, reactor, clock, homeserver):
         self.event_creator = homeserver.get_event_creation_handler()
         homeserver.config.consent.user_consent_version = self.CONSENT_VERSION
 
-    def test_send_dummy_event(self):
+    def test_send_dummy_event(self) -> None:
         self._create_extremity_rich_graph()
 
         # Pump the reactor repeatedly so that the background updates have a
@@ -286,7 +295,7 @@ def test_send_dummy_event(self):
         self.assertTrue(len(latest_event_ids) < 10, len(latest_event_ids))
 
     @patch("synapse.handlers.message._DUMMY_EVENT_ROOM_EXCLUSION_EXPIRY", new=0)
-    def test_send_dummy_events_when_insufficient_power(self):
+    def test_send_dummy_events_when_insufficient_power(self) -> None:
         self._create_extremity_rich_graph()
         # Criple power levels
         self.helper.send_state(
@@ -317,7 +326,7 @@ def test_send_dummy_events_when_insufficient_power(self):
         self.assertTrue(len(latest_event_ids) < 10, len(latest_event_ids))
 
     @patch("synapse.handlers.message._DUMMY_EVENT_ROOM_EXCLUSION_EXPIRY", new=250)
-    def test_expiry_logic(self):
+    def test_expiry_logic(self) -> None:
         """Simple test to ensure that _expire_rooms_to_exclude_from_dummy_event_insertion()
         expires old entries correctly.
         """
@@ -357,7 +366,7 @@ def test_expiry_logic(self):
             0,
         )
 
-    def _create_extremity_rich_graph(self):
+    def _create_extremity_rich_graph(self) -> None:
         """Helper method to create bushy graph on demand"""
 
         event_id_start = self.create_and_send_event(self.room_id, self.user)
@@ -372,7 +381,7 @@ def _create_extremity_rich_graph(self):
         )
         self.assertEqual(len(latest_event_ids), 50)
 
-    def _enable_consent_checking(self):
+    def _enable_consent_checking(self) -> None:
         """Helper method to enable consent checking"""
         self.event_creator._block_events_without_consent_error = "No consent from user"
         consent_uri_builder = Mock()
diff --git a/tests/storage/test_client_ips.py b/tests/storage/test_client_ips.py
index 49ad3c132425..7f7f4ef892bd 100644
--- a/tests/storage/test_client_ips.py
+++ b/tests/storage/test_client_ips.py
@@ -13,15 +13,20 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from typing import Any, Dict
 from unittest.mock import Mock
 
 from parameterized import parameterized
 
+from twisted.test.proto_helpers import MemoryReactor
+
 import synapse.rest.admin
 from synapse.http.site import XForwardedForRequest
 from synapse.rest.client import login
+from synapse.server import HomeServer
 from synapse.storage.databases.main.client_ips import LAST_SEEN_GRANULARITY
 from synapse.types import UserID
+from synapse.util import Clock
 
 from tests import unittest
 from tests.server import make_request
@@ -30,14 +35,10 @@
 
 
 class ClientIpStoreTestCase(unittest.HomeserverTestCase):
-    def make_homeserver(self, reactor, clock):
-        hs = self.setup_test_homeserver()
-        return hs
-
-    def prepare(self, hs, reactor, clock):
-        self.store = self.hs.get_datastores().main
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
+        self.store = hs.get_datastores().main
 
-    def test_insert_new_client_ip(self):
+    def test_insert_new_client_ip(self) -> None:
         self.reactor.advance(12345678)
 
         user_id = "@user:id"
@@ -76,7 +77,7 @@ def test_insert_new_client_ip(self):
             r,
         )
 
-    def test_insert_new_client_ip_none_device_id(self):
+    def test_insert_new_client_ip_none_device_id(self) -> None:
         """
         An insert with a device ID of NULL will not create a new entry, but
         update an existing entry in the user_ips table.
@@ -148,7 +149,7 @@ def test_insert_new_client_ip_none_device_id(self):
         )
 
     @parameterized.expand([(False,), (True,)])
-    def test_get_last_client_ip_by_device(self, after_persisting: bool):
+    def test_get_last_client_ip_by_device(self, after_persisting: bool) -> None:
         """Test `get_last_client_ip_by_device` for persisted and unpersisted data"""
         self.reactor.advance(12345678)
 
@@ -211,7 +212,7 @@ def test_get_last_client_ip_by_device(self, after_persisting: bool):
             },
         )
 
-    def test_get_last_client_ip_by_device_combined_data(self):
+    def test_get_last_client_ip_by_device_combined_data(self) -> None:
         """Test that `get_last_client_ip_by_device` combines persisted and unpersisted
         data together correctly
         """
@@ -310,7 +311,7 @@ def test_get_last_client_ip_by_device_combined_data(self):
         )
 
     @parameterized.expand([(False,), (True,)])
-    def test_get_user_ip_and_agents(self, after_persisting: bool):
+    def test_get_user_ip_and_agents(self, after_persisting: bool) -> None:
         """Test `get_user_ip_and_agents` for persisted and unpersisted data"""
         self.reactor.advance(12345678)
 
@@ -350,7 +351,7 @@ def test_get_user_ip_and_agents(self, after_persisting: bool):
             ],
         )
 
-    def test_get_user_ip_and_agents_combined_data(self):
+    def test_get_user_ip_and_agents_combined_data(self) -> None:
         """Test that `get_user_ip_and_agents` combines persisted and unpersisted data
         together correctly
         """
@@ -427,7 +428,7 @@ def test_get_user_ip_and_agents_combined_data(self):
         )
 
     @override_config({"limit_usage_by_mau": False, "max_mau_value": 50})
-    def test_disabled_monthly_active_user(self):
+    def test_disabled_monthly_active_user(self) -> None:
         user_id = "@user:server"
         self.get_success(
             self.store.insert_client_ip(
@@ -438,7 +439,7 @@ def test_disabled_monthly_active_user(self):
         self.assertFalse(active)
 
     @override_config({"limit_usage_by_mau": True, "max_mau_value": 50})
-    def test_adding_monthly_active_user_when_full(self):
+    def test_adding_monthly_active_user_when_full(self) -> None:
         lots_of_users = 100
         user_id = "@user:server"
 
@@ -454,7 +455,7 @@ def test_adding_monthly_active_user_when_full(self):
         self.assertFalse(active)
 
     @override_config({"limit_usage_by_mau": True, "max_mau_value": 50})
-    def test_adding_monthly_active_user_when_space(self):
+    def test_adding_monthly_active_user_when_space(self) -> None:
         user_id = "@user:server"
         active = self.get_success(self.store.user_last_seen_monthly_active(user_id))
         self.assertFalse(active)
@@ -471,7 +472,7 @@ def test_adding_monthly_active_user_when_space(self):
         self.assertTrue(active)
 
     @override_config({"limit_usage_by_mau": True, "max_mau_value": 50})
-    def test_updating_monthly_active_user_when_space(self):
+    def test_updating_monthly_active_user_when_space(self) -> None:
         user_id = "@user:server"
         self.get_success(self.store.register_user(user_id=user_id, password_hash=None))
 
@@ -489,7 +490,7 @@ def test_updating_monthly_active_user_when_space(self):
         active = self.get_success(self.store.user_last_seen_monthly_active(user_id))
         self.assertTrue(active)
 
-    def test_devices_last_seen_bg_update(self):
+    def test_devices_last_seen_bg_update(self) -> None:
         # First make sure we have completed all updates.
         self.wait_for_background_updates()
 
@@ -574,7 +575,7 @@ def test_devices_last_seen_bg_update(self):
             r,
         )
 
-    def test_old_user_ips_pruned(self):
+    def test_old_user_ips_pruned(self) -> None:
         # First make sure we have completed all updates.
         self.wait_for_background_updates()
 
@@ -637,11 +638,11 @@ def test_old_user_ips_pruned(self):
         self.assertEqual(result, [])
 
         # But we should still get the correct values for the device
-        result = self.get_success(
+        result2 = self.get_success(
             self.store.get_last_client_ip_by_device(user_id, device_id)
         )
 
-        r = result[(user_id, device_id)]
+        r = result2[(user_id, device_id)]
         self.assertDictContainsSubset(
             {
                 "user_id": user_id,
@@ -661,15 +662,11 @@ class ClientIpAuthTestCase(unittest.HomeserverTestCase):
         login.register_servlets,
     ]
 
-    def make_homeserver(self, reactor, clock):
-        hs = self.setup_test_homeserver()
-        return hs
-
-    def prepare(self, hs, reactor, clock):
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         self.store = self.hs.get_datastores().main
         self.user_id = self.register_user("bob", "abc123", True)
 
-    def test_request_with_xforwarded(self):
+    def test_request_with_xforwarded(self) -> None:
         """
         The IP in X-Forwarded-For is entered into the client IPs table.
         """
@@ -679,14 +676,19 @@ def test_request_with_xforwarded(self):
             {"request": XForwardedForRequest},
         )
 
-    def test_request_from_getPeer(self):
+    def test_request_from_getPeer(self) -> None:
         """
         The IP returned by getPeer is entered into the client IPs table, if
         there's no X-Forwarded-For header.
         """
         self._runtest({}, "127.0.0.1", {})
 
-    def _runtest(self, headers, expected_ip, make_request_args):
+    def _runtest(
+        self,
+        headers: Dict[bytes, bytes],
+        expected_ip: str,
+        make_request_args: Dict[str, Any],
+    ) -> None:
         device_id = "bleb"
 
         access_token = self.login("bob", "abc123", device_id=device_id)
diff --git a/tests/storage/test_database.py b/tests/storage/test_database.py
index a40fc20ef990..543cce6b3e12 100644
--- a/tests/storage/test_database.py
+++ b/tests/storage/test_database.py
@@ -31,7 +31,7 @@
 
 
 class TupleComparisonClauseTestCase(unittest.TestCase):
-    def test_native_tuple_comparison(self):
+    def test_native_tuple_comparison(self) -> None:
         clause, args = make_tuple_comparison_clause([("a", 1), ("b", 2)])
         self.assertEqual(clause, "(a,b) > (?,?)")
         self.assertEqual(args, [1, 2])
diff --git a/tests/storage/test_devices.py b/tests/storage/test_devices.py
index 8e7db2c4ec39..f03807c8f9d4 100644
--- a/tests/storage/test_devices.py
+++ b/tests/storage/test_devices.py
@@ -12,17 +12,24 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from typing import Collection, List, Tuple
+
+from twisted.test.proto_helpers import MemoryReactor
+
 import synapse.api.errors
 from synapse.api.constants import EduTypes
+from synapse.server import HomeServer
+from synapse.types import JsonDict
+from synapse.util import Clock
 
 from tests.unittest import HomeserverTestCase
 
 
 class DeviceStoreTestCase(HomeserverTestCase):
-    def prepare(self, reactor, clock, hs):
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         self.store = hs.get_datastores().main
 
-    def add_device_change(self, user_id, device_ids, host):
+    def add_device_change(self, user_id: str, device_ids: List[str], host: str) -> None:
         """Add a device list change for the given device to
         `device_lists_outbound_pokes` table.
         """
@@ -44,12 +51,13 @@ def add_device_change(self, user_id, device_ids, host):
                 )
             )
 
-    def test_store_new_device(self):
+    def test_store_new_device(self) -> None:
         self.get_success(
             self.store.store_device("user_id", "device_id", "display_name")
         )
 
         res = self.get_success(self.store.get_device("user_id", "device_id"))
+        assert res is not None
         self.assertDictContainsSubset(
             {
                 "user_id": "user_id",
@@ -59,7 +67,7 @@ def test_store_new_device(self):
             res,
         )
 
-    def test_get_devices_by_user(self):
+    def test_get_devices_by_user(self) -> None:
         self.get_success(
             self.store.store_device("user_id", "device1", "display_name 1")
         )
@@ -89,7 +97,7 @@ def test_get_devices_by_user(self):
             res["device2"],
         )
 
-    def test_count_devices_by_users(self):
+    def test_count_devices_by_users(self) -> None:
         self.get_success(
             self.store.store_device("user_id", "device1", "display_name 1")
         )
@@ -114,7 +122,7 @@ def test_count_devices_by_users(self):
         )
         self.assertEqual(3, res)
 
-    def test_get_device_updates_by_remote(self):
+    def test_get_device_updates_by_remote(self) -> None:
         device_ids = ["device_id1", "device_id2"]
 
         # Add two device updates with sequential `stream_id`s
@@ -128,7 +136,7 @@ def test_get_device_updates_by_remote(self):
         # Check original device_ids are contained within these updates
         self._check_devices_in_updates(device_ids, device_updates)
 
-    def test_get_device_updates_by_remote_can_limit_properly(self):
+    def test_get_device_updates_by_remote_can_limit_properly(self) -> None:
         """
         Tests that `get_device_updates_by_remote` returns an appropriate
         stream_id to resume fetching from (without skipping any results).
@@ -280,7 +288,11 @@ def test_get_device_updates_by_remote_cross_signing_key_updates(
         )
         self.assertEqual(device_updates, [])
 
-    def _check_devices_in_updates(self, expected_device_ids, device_updates):
+    def _check_devices_in_updates(
+        self,
+        expected_device_ids: Collection[str],
+        device_updates: List[Tuple[str, JsonDict]],
+    ) -> None:
         """Check that an specific device ids exist in a list of device update EDUs"""
         self.assertEqual(len(device_updates), len(expected_device_ids))
 
@@ -289,17 +301,19 @@ def _check_devices_in_updates(self, expected_device_ids, device_updates):
         }
         self.assertEqual(received_device_ids, set(expected_device_ids))
 
-    def test_update_device(self):
+    def test_update_device(self) -> None:
         self.get_success(
             self.store.store_device("user_id", "device_id", "display_name 1")
         )
 
         res = self.get_success(self.store.get_device("user_id", "device_id"))
+        assert res is not None
         self.assertEqual("display_name 1", res["display_name"])
 
         # do a no-op first
         self.get_success(self.store.update_device("user_id", "device_id"))
         res = self.get_success(self.store.get_device("user_id", "device_id"))
+        assert res is not None
         self.assertEqual("display_name 1", res["display_name"])
 
         # do the update
@@ -311,9 +325,10 @@ def test_update_device(self):
 
         # check it worked
         res = self.get_success(self.store.get_device("user_id", "device_id"))
+        assert res is not None
         self.assertEqual("display_name 2", res["display_name"])
 
-    def test_update_unknown_device(self):
+    def test_update_unknown_device(self) -> None:
         exc = self.get_failure(
             self.store.update_device(
                 "user_id", "unknown_device_id", new_display_name="display_name 2"
diff --git a/tests/storage/test_directory.py b/tests/storage/test_directory.py
index 20bf3ca17b9a..8bedc6bdf350 100644
--- a/tests/storage/test_directory.py
+++ b/tests/storage/test_directory.py
@@ -12,19 +12,23 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from twisted.test.proto_helpers import MemoryReactor
+
+from synapse.server import HomeServer
 from synapse.types import RoomAlias, RoomID
+from synapse.util import Clock
 
 from tests.unittest import HomeserverTestCase
 
 
 class DirectoryStoreTestCase(HomeserverTestCase):
-    def prepare(self, reactor, clock, hs):
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         self.store = hs.get_datastores().main
 
         self.room = RoomID.from_string("!abcde:test")
         self.alias = RoomAlias.from_string("#my-room:test")
 
-    def test_room_to_alias(self):
+    def test_room_to_alias(self) -> None:
         self.get_success(
             self.store.create_room_alias_association(
                 room_alias=self.alias, room_id=self.room.to_string(), servers=["test"]
@@ -36,7 +40,7 @@ def test_room_to_alias(self):
             (self.get_success(self.store.get_aliases_for_room(self.room.to_string()))),
         )
 
-    def test_alias_to_room(self):
+    def test_alias_to_room(self) -> None:
         self.get_success(
             self.store.create_room_alias_association(
                 room_alias=self.alias, room_id=self.room.to_string(), servers=["test"]
@@ -48,7 +52,7 @@ def test_alias_to_room(self):
             (self.get_success(self.store.get_association_from_room_alias(self.alias))),
         )
 
-    def test_delete_alias(self):
+    def test_delete_alias(self) -> None:
         self.get_success(
             self.store.create_room_alias_association(
                 room_alias=self.alias, room_id=self.room.to_string(), servers=["test"]
diff --git a/tests/storage/test_e2e_room_keys.py b/tests/storage/test_e2e_room_keys.py
index fb96ab3a2fd0..9cb326d90a87 100644
--- a/tests/storage/test_e2e_room_keys.py
+++ b/tests/storage/test_e2e_room_keys.py
@@ -12,7 +12,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from twisted.test.proto_helpers import MemoryReactor
+
+from synapse.server import HomeServer
 from synapse.storage.databases.main.e2e_room_keys import RoomKey
+from synapse.util import Clock
 
 from tests import unittest
 
@@ -26,12 +30,12 @@
 
 
 class E2eRoomKeysHandlerTestCase(unittest.HomeserverTestCase):
-    def make_homeserver(self, reactor, clock):
+    def make_homeserver(self, reactor: MemoryReactor, clock: Clock) -> HomeServer:
         hs = self.setup_test_homeserver("server", federation_http_client=None)
         self.store = hs.get_datastores().main
         return hs
 
-    def test_room_keys_version_delete(self):
+    def test_room_keys_version_delete(self) -> None:
         # test that deleting a room key backup deletes the keys
         version1 = self.get_success(
             self.store.create_e2e_room_keys_version(
diff --git a/tests/storage/test_end_to_end_keys.py b/tests/storage/test_end_to_end_keys.py
index 0f04493ad06c..5fde3b9c7879 100644
--- a/tests/storage/test_end_to_end_keys.py
+++ b/tests/storage/test_end_to_end_keys.py
@@ -12,14 +12,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from twisted.test.proto_helpers import MemoryReactor
+
+from synapse.server import HomeServer
+from synapse.util import Clock
+
 from tests.unittest import HomeserverTestCase
 
 
 class EndToEndKeyStoreTestCase(HomeserverTestCase):
-    def prepare(self, reactor, clock, hs):
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         self.store = hs.get_datastores().main
 
-    def test_key_without_device_name(self):
+    def test_key_without_device_name(self) -> None:
         now = 1470174257070
         json = {"key": "value"}
 
@@ -35,7 +40,7 @@ def test_key_without_device_name(self):
         dev = res["user"]["device"]
         self.assertDictContainsSubset(json, dev)
 
-    def test_reupload_key(self):
+    def test_reupload_key(self) -> None:
         now = 1470174257070
         json = {"key": "value"}
 
@@ -53,7 +58,7 @@ def test_reupload_key(self):
         )
         self.assertFalse(changed)
 
-    def test_get_key_with_device_name(self):
+    def test_get_key_with_device_name(self) -> None:
         now = 1470174257070
         json = {"key": "value"}
 
@@ -70,7 +75,7 @@ def test_get_key_with_device_name(self):
             {"key": "value", "unsigned": {"device_display_name": "display_name"}}, dev
         )
 
-    def test_multiple_devices(self):
+    def test_multiple_devices(self) -> None:
         now = 1470174257070
 
         self.get_success(self.store.store_device("user1", "device1", None))
diff --git a/tests/storage/test_event_chain.py b/tests/storage/test_event_chain.py
index de9f4af2de90..c070278db80f 100644
--- a/tests/storage/test_event_chain.py
+++ b/tests/storage/test_event_chain.py
@@ -14,6 +14,7 @@
 
 from typing import Dict, List, Set, Tuple
 
+from twisted.test.proto_helpers import MemoryReactor
 from twisted.trial import unittest
 
 from synapse.api.constants import EventTypes
@@ -22,18 +23,22 @@
 from synapse.events.snapshot import EventContext
 from synapse.rest import admin
 from synapse.rest.client import login, room
+from synapse.server import HomeServer
+from synapse.storage.database import LoggingTransaction
 from synapse.storage.databases.main.events import _LinkMap
+from synapse.storage.types import Cursor
 from synapse.types import create_requester
+from synapse.util import Clock
 
 from tests.unittest import HomeserverTestCase
 
 
 class EventChainStoreTestCase(HomeserverTestCase):
-    def prepare(self, reactor, clock, hs):
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         self.store = hs.get_datastores().main
         self._next_stream_ordering = 1
 
-    def test_simple(self):
+    def test_simple(self) -> None:
         """Test that the example in `docs/auth_chain_difference_algorithm.md`
         works.
         """
@@ -232,7 +237,7 @@ def test_simple(self):
                 ),
             )
 
-    def test_out_of_order_events(self):
+    def test_out_of_order_events(self) -> None:
         """Test that we handle persisting events that we don't have the full
         auth chain for yet (which should only happen for out of band memberships).
         """
@@ -378,7 +383,7 @@ def test_out_of_order_events(self):
     def persist(
         self,
         events: List[EventBase],
-    ):
+    ) -> None:
         """Persist the given events and check that the links generated match
         those given.
         """
@@ -389,7 +394,7 @@ def persist(
             e.internal_metadata.stream_ordering = self._next_stream_ordering
             self._next_stream_ordering += 1
 
-        def _persist(txn):
+        def _persist(txn: LoggingTransaction) -> None:
             # We need to persist the events to the events and state_events
             # tables.
             persist_events_store._store_event_txn(
@@ -456,7 +461,7 @@ def fetch_chains(
 
 
 class LinkMapTestCase(unittest.TestCase):
-    def test_simple(self):
+    def test_simple(self) -> None:
         """Basic tests for the LinkMap."""
         link_map = _LinkMap()
 
@@ -492,7 +497,7 @@ class EventChainBackgroundUpdateTestCase(HomeserverTestCase):
         login.register_servlets,
     ]
 
-    def prepare(self, reactor, clock, hs):
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         self.store = hs.get_datastores().main
         self.user_id = self.register_user("foo", "pass")
         self.token = self.login("foo", "pass")
@@ -559,7 +564,7 @@ def _generate_room(self) -> Tuple[str, List[Set[str]]]:
 
         # Delete the chain cover info.
 
-        def _delete_tables(txn):
+        def _delete_tables(txn: Cursor) -> None:
             txn.execute("DELETE FROM event_auth_chains")
             txn.execute("DELETE FROM event_auth_chain_links")
 
@@ -567,7 +572,7 @@ def _delete_tables(txn):
 
         return room_id, [state1, state2]
 
-    def test_background_update_single_room(self):
+    def test_background_update_single_room(self) -> None:
         """Test that the background update to calculate auth chains for historic
         rooms works correctly.
         """
@@ -602,7 +607,7 @@ def test_background_update_single_room(self):
             )
         )
 
-    def test_background_update_multiple_rooms(self):
+    def test_background_update_multiple_rooms(self) -> None:
         """Test that the background update to calculate auth chains for historic
         rooms works correctly.
         """
@@ -640,7 +645,7 @@ def test_background_update_multiple_rooms(self):
             )
         )
 
-    def test_background_update_single_large_room(self):
+    def test_background_update_single_large_room(self) -> None:
         """Test that the background update to calculate auth chains for historic
         rooms works correctly.
         """
@@ -693,7 +698,7 @@ def test_background_update_single_large_room(self):
             )
         )
 
-    def test_background_update_multiple_large_room(self):
+    def test_background_update_multiple_large_room(self) -> None:
         """Test that the background update to calculate auth chains for historic
         rooms works correctly.
         """
diff --git a/tests/storage/test_event_federation.py b/tests/storage/test_event_federation.py
index 853db930d6af..7fd3e01364e9 100644
--- a/tests/storage/test_event_federation.py
+++ b/tests/storage/test_event_federation.py
@@ -13,7 +13,7 @@
 # limitations under the License.
 
 import datetime
-from typing import Dict, List, Tuple, Union
+from typing import Dict, List, Tuple, Union, cast
 
 import attr
 from parameterized import parameterized
@@ -26,11 +26,12 @@
     EventFormatVersions,
     RoomVersion,
 )
-from synapse.events import _EventInternalMetadata
+from synapse.events import EventBase, _EventInternalMetadata
 from synapse.rest import admin
 from synapse.rest.client import login, room
 from synapse.server import HomeServer
 from synapse.storage.database import LoggingTransaction
+from synapse.storage.types import Cursor
 from synapse.types import JsonDict
 from synapse.util import Clock, json_encoder
 
@@ -54,11 +55,11 @@ class EventFederationWorkerStoreTestCase(tests.unittest.HomeserverTestCase):
     def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         self.store = hs.get_datastores().main
 
-    def test_get_prev_events_for_room(self):
+    def test_get_prev_events_for_room(self) -> None:
         room_id = "@ROOM:local"
 
         # add a bunch of events and hashes to act as forward extremities
-        def insert_event(txn, i):
+        def insert_event(txn: Cursor, i: int) -> None:
             event_id = "$event_%i:local" % i
 
             txn.execute(
@@ -90,12 +91,12 @@ def insert_event(txn, i):
         for i in range(0, 10):
             self.assertEqual("$event_%i:local" % (19 - i), r[i])
 
-    def test_get_rooms_with_many_extremities(self):
+    def test_get_rooms_with_many_extremities(self) -> None:
         room1 = "#room1"
         room2 = "#room2"
         room3 = "#room3"
 
-        def insert_event(txn, i, room_id):
+        def insert_event(txn: Cursor, i: int, room_id: str) -> None:
             event_id = "$event_%i:local" % i
             txn.execute(
                 (
@@ -155,7 +156,7 @@ def _setup_auth_chain(self, use_chain_cover_index: bool) -> str:
         #     |   |
         #     K   J
 
-        auth_graph = {
+        auth_graph: Dict[str, List[str]] = {
             "a": ["e"],
             "b": ["e"],
             "c": ["g", "i"],
@@ -185,7 +186,7 @@ def _setup_auth_chain(self, use_chain_cover_index: bool) -> str:
 
         # Mark the room as maybe having a cover index.
 
-        def store_room(txn):
+        def store_room(txn: LoggingTransaction) -> None:
             self.store.db_pool.simple_insert_txn(
                 txn,
                 "rooms",
@@ -203,7 +204,7 @@ def store_room(txn):
         # We rudely fiddle with the appropriate tables directly, as that's much
         # easier than constructing events properly.
 
-        def insert_event(txn):
+        def insert_event(txn: LoggingTransaction) -> None:
             stream_ordering = 0
 
             for event_id in auth_graph:
@@ -228,7 +229,7 @@ def insert_event(txn):
             self.hs.datastores.persist_events._persist_event_auth_chain_txn(
                 txn,
                 [
-                    FakeEvent(event_id, room_id, auth_graph[event_id])
+                    cast(EventBase, FakeEvent(event_id, room_id, auth_graph[event_id]))
                     for event_id in auth_graph
                 ],
             )
@@ -243,7 +244,7 @@ def insert_event(txn):
         return room_id
 
     @parameterized.expand([(True,), (False,)])
-    def test_auth_chain_ids(self, use_chain_cover_index: bool):
+    def test_auth_chain_ids(self, use_chain_cover_index: bool) -> None:
         room_id = self._setup_auth_chain(use_chain_cover_index)
 
         # a and b have the same auth chain.
@@ -308,7 +309,7 @@ def test_auth_chain_ids(self, use_chain_cover_index: bool):
         self.assertCountEqual(auth_chain_ids, ["i", "j"])
 
     @parameterized.expand([(True,), (False,)])
-    def test_auth_difference(self, use_chain_cover_index: bool):
+    def test_auth_difference(self, use_chain_cover_index: bool) -> None:
         room_id = self._setup_auth_chain(use_chain_cover_index)
 
         # Now actually test that various combinations give the right result:
@@ -353,7 +354,7 @@ def test_auth_difference(self, use_chain_cover_index: bool):
         )
         self.assertSetEqual(difference, set())
 
-    def test_auth_difference_partial_cover(self):
+    def test_auth_difference_partial_cover(self) -> None:
         """Test that we correctly handle rooms where not all events have a chain
         cover calculated. This can happen in some obscure edge cases, including
         during the background update that calculates the chain cover for old
@@ -377,7 +378,7 @@ def test_auth_difference_partial_cover(self):
         #     |   |
         #     K   J
 
-        auth_graph = {
+        auth_graph: Dict[str, List[str]] = {
             "a": ["e"],
             "b": ["e"],
             "c": ["g", "i"],
@@ -408,7 +409,7 @@ def test_auth_difference_partial_cover(self):
         # We rudely fiddle with the appropriate tables directly, as that's much
         # easier than constructing events properly.
 
-        def insert_event(txn):
+        def insert_event(txn: LoggingTransaction) -> None:
             # First insert the room and mark it as having a chain cover.
             self.store.db_pool.simple_insert_txn(
                 txn,
@@ -447,7 +448,7 @@ def insert_event(txn):
             self.hs.datastores.persist_events._persist_event_auth_chain_txn(
                 txn,
                 [
-                    FakeEvent(event_id, room_id, auth_graph[event_id])
+                    cast(EventBase, FakeEvent(event_id, room_id, auth_graph[event_id]))
                     for event_id in auth_graph
                     if event_id != "b"
                 ],
@@ -465,7 +466,7 @@ def insert_event(txn):
 
             self.hs.datastores.persist_events._persist_event_auth_chain_txn(
                 txn,
-                [FakeEvent("b", room_id, auth_graph["b"])],
+                [cast(EventBase, FakeEvent("b", room_id, auth_graph["b"]))],
             )
 
             self.store.db_pool.simple_update_txn(
@@ -527,7 +528,7 @@ def insert_event(txn):
     @parameterized.expand(
         [(room_version,) for room_version in KNOWN_ROOM_VERSIONS.values()]
     )
-    def test_prune_inbound_federation_queue(self, room_version: RoomVersion):
+    def test_prune_inbound_federation_queue(self, room_version: RoomVersion) -> None:
         """Test that pruning of inbound federation queues work"""
 
         room_id = "some_room_id"
@@ -686,7 +687,7 @@ def _setup_room_for_backfill_tests(self) -> _BackfillSetupInfo:
 
             stream_ordering += 1
 
-        def populate_db(txn: LoggingTransaction):
+        def populate_db(txn: LoggingTransaction) -> None:
             # Insert the room to satisfy the foreign key constraint of
             # `event_failed_pull_attempts`
             self.store.db_pool.simple_insert_txn(
@@ -760,7 +761,7 @@ def populate_db(txn: LoggingTransaction):
 
         return _BackfillSetupInfo(room_id=room_id, depth_map=depth_map)
 
-    def test_get_backfill_points_in_room(self):
+    def test_get_backfill_points_in_room(self) -> None:
         """
         Test to make sure only backfill points that are older and come before
         the `current_depth` are returned.
@@ -787,7 +788,7 @@ def test_get_backfill_points_in_room(self):
 
     def test_get_backfill_points_in_room_excludes_events_we_have_attempted(
         self,
-    ):
+    ) -> None:
         """
         Test to make sure that events we have attempted to backfill (and within
         backoff timeout duration) do not show up as an event to backfill again.
@@ -824,7 +825,7 @@ def test_get_backfill_points_in_room_excludes_events_we_have_attempted(
 
     def test_get_backfill_points_in_room_attempted_event_retry_after_backoff_duration(
         self,
-    ):
+    ) -> None:
         """
         Test to make sure after we fake attempt to backfill event "b3" many times,
         we can see retry and see the "b3" again after the backoff timeout duration
@@ -941,7 +942,7 @@ def _setup_room_for_insertion_backfill_tests(self) -> _BackfillSetupInfo:
             "5": 7,
         }
 
-        def populate_db(txn: LoggingTransaction):
+        def populate_db(txn: LoggingTransaction) -> None:
             # Insert the room to satisfy the foreign key constraint of
             # `event_failed_pull_attempts`
             self.store.db_pool.simple_insert_txn(
@@ -996,7 +997,7 @@ def populate_db(txn: LoggingTransaction):
 
         return _BackfillSetupInfo(room_id=room_id, depth_map=depth_map)
 
-    def test_get_insertion_event_backward_extremities_in_room(self):
+    def test_get_insertion_event_backward_extremities_in_room(self) -> None:
         """
         Test to make sure only insertion event backward extremities that are
         older and come before the `current_depth` are returned.
@@ -1027,7 +1028,7 @@ def test_get_insertion_event_backward_extremities_in_room(self):
 
     def test_get_insertion_event_backward_extremities_in_room_excludes_events_we_have_attempted(
         self,
-    ):
+    ) -> None:
         """
         Test to make sure that insertion events we have attempted to backfill
         (and within backoff timeout duration) do not show up as an event to
@@ -1060,7 +1061,7 @@ def test_get_insertion_event_backward_extremities_in_room_excludes_events_we_hav
 
     def test_get_insertion_event_backward_extremities_in_room_attempted_event_retry_after_backoff_duration(
         self,
-    ):
+    ) -> None:
         """
         Test to make sure after we fake attempt to backfill event
         "insertion_eventA" many times, we can see retry and see the
@@ -1130,9 +1131,7 @@ def test_get_insertion_event_backward_extremities_in_room_attempted_event_retry_
         backfill_event_ids = [backfill_point[0] for backfill_point in backfill_points]
         self.assertEqual(backfill_event_ids, ["insertion_eventA"])
 
-    def test_get_event_ids_to_not_pull_from_backoff(
-        self,
-    ):
+    def test_get_event_ids_to_not_pull_from_backoff(self) -> None:
         """
         Test to make sure only event IDs we should backoff from are returned.
         """
@@ -1157,7 +1156,7 @@ def test_get_event_ids_to_not_pull_from_backoff(
 
     def test_get_event_ids_to_not_pull_from_backoff_retry_after_backoff_duration(
         self,
-    ):
+    ) -> None:
         """
         Test to make sure no event IDs are returned after the backoff duration has
         elapsed.
@@ -1187,19 +1186,19 @@ def test_get_event_ids_to_not_pull_from_backoff_retry_after_backoff_duration(
         self.assertEqual(event_ids_to_backoff, [])
 
 
-@attr.s
+@attr.s(auto_attribs=True)
 class FakeEvent:
-    event_id = attr.ib()
-    room_id = attr.ib()
-    auth_events = attr.ib()
+    event_id: str
+    room_id: str
+    auth_events: List[str]
 
     type = "foo"
     state_key = "foo"
 
     internal_metadata = _EventInternalMetadata({})
 
-    def auth_event_ids(self):
+    def auth_event_ids(self) -> List[str]:
         return self.auth_events
 
-    def is_state(self):
+    def is_state(self) -> bool:
         return True
diff --git a/tests/storage/test_event_metrics.py b/tests/storage/test_event_metrics.py
index 6f1135eef4da..a91411168cdd 100644
--- a/tests/storage/test_event_metrics.py
+++ b/tests/storage/test_event_metrics.py
@@ -20,7 +20,7 @@
 
 
 class ExtremStatisticsTestCase(HomeserverTestCase):
-    def test_exposed_to_prometheus(self):
+    def test_exposed_to_prometheus(self) -> None:
         """
         Forward extremity counts are exposed via Prometheus.
         """
diff --git a/tests/storage/test_events.py b/tests/storage/test_events.py
index 3ce4f35cb74d..05661a537dbd 100644
--- a/tests/storage/test_events.py
+++ b/tests/storage/test_events.py
@@ -12,12 +12,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from typing import List, Optional
+
+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.federation.federation_base import event_from_pdu_json
 from synapse.rest import admin
 from synapse.rest.client import login, room
+from synapse.server import HomeServer
+from synapse.types import StateMap
+from synapse.util import Clock
 
 from tests.unittest import HomeserverTestCase
 
@@ -29,7 +36,9 @@ class ExtremPruneTestCase(HomeserverTestCase):
         login.register_servlets,
     ]
 
-    def prepare(self, reactor, clock, homeserver):
+    def prepare(
+        self, reactor: MemoryReactor, clock: Clock, homeserver: HomeServer
+    ) -> None:
         self.state = self.hs.get_state_handler()
         self._persistence = self.hs.get_storage_controllers().persistence
         self._state_storage_controller = self.hs.get_storage_controllers().state
@@ -67,7 +76,9 @@ def prepare(self, reactor, clock, homeserver):
         # Check that the current extremities is the remote event.
         self.assert_extremities([self.remote_event_1.event_id])
 
-    def persist_event(self, event, state=None):
+    def persist_event(
+        self, event: EventBase, state: Optional[StateMap[str]] = None
+    ) -> None:
         """Persist the event, with optional state"""
         context = self.get_success(
             self.state.compute_event_context(
@@ -78,14 +89,14 @@ def persist_event(self, event, state=None):
         )
         self.get_success(self._persistence.persist_event(event, context))
 
-    def assert_extremities(self, expected_extremities):
+    def assert_extremities(self, expected_extremities: List[str]) -> None:
         """Assert the current extremities for the room"""
         extremities = self.get_success(
             self.store.get_prev_events_for_room(self.room_id)
         )
         self.assertCountEqual(extremities, expected_extremities)
 
-    def test_prune_gap(self):
+    def test_prune_gap(self) -> None:
         """Test that we drop extremities after a gap when we see an event from
         the same domain.
         """
@@ -117,7 +128,7 @@ def test_prune_gap(self):
         # Check the new extremity is just the new remote event.
         self.assert_extremities([remote_event_2.event_id])
 
-    def test_do_not_prune_gap_if_state_different(self):
+    def test_do_not_prune_gap_if_state_different(self) -> None:
         """Test that we don't prune extremities after a gap if the resolved
         state is different.
         """
@@ -161,7 +172,7 @@ def test_do_not_prune_gap_if_state_different(self):
         # Check that we haven't dropped the old extremity.
         self.assert_extremities([self.remote_event_1.event_id, remote_event_2.event_id])
 
-    def test_prune_gap_if_old(self):
+    def test_prune_gap_if_old(self) -> None:
         """Test that we drop extremities after a gap when the previous extremity
         is "old"
         """
@@ -197,7 +208,7 @@ def test_prune_gap_if_old(self):
         # Check the new extremity is just the new remote event.
         self.assert_extremities([remote_event_2.event_id])
 
-    def test_do_not_prune_gap_if_other_server(self):
+    def test_do_not_prune_gap_if_other_server(self) -> None:
         """Test that we do not drop extremities after a gap when we see an event
         from a different domain.
         """
@@ -229,7 +240,7 @@ def test_do_not_prune_gap_if_other_server(self):
         # Check the new extremity is just the new remote event.
         self.assert_extremities([self.remote_event_1.event_id, remote_event_2.event_id])
 
-    def test_prune_gap_if_dummy_remote(self):
+    def test_prune_gap_if_dummy_remote(self) -> None:
         """Test that we drop extremities after a gap when the previous extremity
         is a local dummy event and only points to remote events.
         """
@@ -271,7 +282,7 @@ def test_prune_gap_if_dummy_remote(self):
         # Check the new extremity is just the new remote event.
         self.assert_extremities([remote_event_2.event_id])
 
-    def test_prune_gap_if_dummy_local(self):
+    def test_prune_gap_if_dummy_local(self) -> None:
         """Test that we don't drop extremities after a gap when the previous
         extremity is a local dummy event and points to local events.
         """
@@ -315,7 +326,7 @@ def test_prune_gap_if_dummy_local(self):
         # Check the new extremity is just the new remote event.
         self.assert_extremities([remote_event_2.event_id, local_message_event_id])
 
-    def test_do_not_prune_gap_if_not_dummy(self):
+    def test_do_not_prune_gap_if_not_dummy(self) -> None:
         """Test that we do not drop extremities after a gap when the previous extremity
         is not a dummy event.
         """
@@ -359,12 +370,14 @@ class InvalideUsersInRoomCacheTestCase(HomeserverTestCase):
         login.register_servlets,
     ]
 
-    def prepare(self, reactor, clock, homeserver):
+    def prepare(
+        self, reactor: MemoryReactor, clock: Clock, homeserver: HomeServer
+    ) -> None:
         self.state = self.hs.get_state_handler()
         self._persistence = self.hs.get_storage_controllers().persistence
         self.store = self.hs.get_datastores().main
 
-    def test_remote_user_rooms_cache_invalidated(self):
+    def test_remote_user_rooms_cache_invalidated(self) -> None:
         """Test that if the server leaves a room the `get_rooms_for_user` cache
         is invalidated for remote users.
         """
@@ -411,7 +424,7 @@ def test_remote_user_rooms_cache_invalidated(self):
         rooms = self.get_success(self.store.get_rooms_for_user(remote_user))
         self.assertEqual(set(rooms), set())
 
-    def test_room_remote_user_cache_invalidated(self):
+    def test_room_remote_user_cache_invalidated(self) -> None:
         """Test that if the server leaves a room the `get_users_in_room` cache
         is invalidated for remote users.
         """
diff --git a/tests/storage/test_keys.py b/tests/storage/test_keys.py
index 9059095525e0..aa4b5bd3b18d 100644
--- a/tests/storage/test_keys.py
+++ b/tests/storage/test_keys.py
@@ -13,6 +13,7 @@
 # limitations under the License.
 
 import signedjson.key
+import signedjson.types
 import unpaddedbase64
 
 from twisted.internet.defer import Deferred
@@ -22,7 +23,9 @@
 import tests.unittest
 
 
-def decode_verify_key_base64(key_id: str, key_base64: str):
+def decode_verify_key_base64(
+    key_id: str, key_base64: str
+) -> signedjson.types.VerifyKey:
     key_bytes = unpaddedbase64.decode_base64(key_base64)
     return signedjson.key.decode_verify_key_bytes(key_id, key_bytes)
 
@@ -36,7 +39,7 @@ def decode_verify_key_base64(key_id: str, key_base64: str):
 
 
 class KeyStoreTestCase(tests.unittest.HomeserverTestCase):
-    def test_get_server_verify_keys(self):
+    def test_get_server_verify_keys(self) -> None:
         store = self.hs.get_datastores().main
 
         key_id_1 = "ed25519:key1"
@@ -71,7 +74,7 @@ def test_get_server_verify_keys(self):
         # non-existent result gives None
         self.assertIsNone(res[("server1", "ed25519:key3")])
 
-    def test_cache(self):
+    def test_cache(self) -> None:
         """Check that updates correctly invalidate the cache."""
 
         store = self.hs.get_datastores().main
diff --git a/tests/storage/test_monthly_active_users.py b/tests/storage/test_monthly_active_users.py
index c55c4db97033..282773837907 100644
--- a/tests/storage/test_monthly_active_users.py
+++ b/tests/storage/test_monthly_active_users.py
@@ -53,7 +53,7 @@ def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         self.reactor.advance(FORTY_DAYS)
 
     @override_config({"max_mau_value": 3, "mau_limit_reserved_threepids": gen_3pids(3)})
-    def test_initialise_reserved_users(self):
+    def test_initialise_reserved_users(self) -> None:
         threepids = self.hs.config.server.mau_limits_reserved_threepids
 
         # register three users, of which two have reserved 3pids, and a third
@@ -133,7 +133,7 @@ def test_initialise_reserved_users(self):
         active_count = self.get_success(self.store.get_monthly_active_count())
         self.assertEqual(active_count, 3)
 
-    def test_can_insert_and_count_mau(self):
+    def test_can_insert_and_count_mau(self) -> None:
         count = self.get_success(self.store.get_monthly_active_count())
         self.assertEqual(count, 0)
 
@@ -143,7 +143,7 @@ def test_can_insert_and_count_mau(self):
         count = self.get_success(self.store.get_monthly_active_count())
         self.assertEqual(count, 1)
 
-    def test_appservice_user_not_counted_in_mau(self):
+    def test_appservice_user_not_counted_in_mau(self) -> None:
         self.get_success(
             self.store.register_user(
                 user_id="@appservice_user:server", appservice_id="wibble"
@@ -158,7 +158,7 @@ def test_appservice_user_not_counted_in_mau(self):
         count = self.get_success(self.store.get_monthly_active_count())
         self.assertEqual(count, 0)
 
-    def test_user_last_seen_monthly_active(self):
+    def test_user_last_seen_monthly_active(self) -> None:
         user_id1 = "@user1:server"
         user_id2 = "@user2:server"
         user_id3 = "@user3:server"
@@ -177,7 +177,7 @@ def test_user_last_seen_monthly_active(self):
         self.assertIsNone(result)
 
     @override_config({"max_mau_value": 5})
-    def test_reap_monthly_active_users(self):
+    def test_reap_monthly_active_users(self) -> None:
         initial_users = 10
         for i in range(initial_users):
             self.get_success(
@@ -204,7 +204,7 @@ def test_reap_monthly_active_users(self):
     # Note that below says mau_limit (no s), this is the name of the config
     # value, although it gets stored on the config object as mau_limits.
     @override_config({"max_mau_value": 5, "mau_limit_reserved_threepids": gen_3pids(5)})
-    def test_reap_monthly_active_users_reserved_users(self):
+    def test_reap_monthly_active_users_reserved_users(self) -> None:
         """Tests that reaping correctly handles reaping where reserved users are
         present"""
         threepids = self.hs.config.server.mau_limits_reserved_threepids
@@ -244,7 +244,7 @@ def test_reap_monthly_active_users_reserved_users(self):
         count = self.get_success(self.store.get_monthly_active_count())
         self.assertEqual(count, self.hs.config.server.max_mau_value)
 
-    def test_populate_monthly_users_is_guest(self):
+    def test_populate_monthly_users_is_guest(self) -> None:
         # Test that guest users are not added to mau list
         user_id = "@user_id:host"
 
@@ -260,7 +260,7 @@ def test_populate_monthly_users_is_guest(self):
 
         self.store.upsert_monthly_active_user.assert_not_called()
 
-    def test_populate_monthly_users_should_update(self):
+    def test_populate_monthly_users_should_update(self) -> None:
         self.store.upsert_monthly_active_user = Mock(return_value=make_awaitable(None))  # type: ignore[assignment]
 
         self.store.is_trial_user = Mock(return_value=make_awaitable(False))  # type: ignore[assignment]
@@ -273,7 +273,7 @@ def test_populate_monthly_users_should_update(self):
 
         self.store.upsert_monthly_active_user.assert_called_once()
 
-    def test_populate_monthly_users_should_not_update(self):
+    def test_populate_monthly_users_should_not_update(self) -> None:
         self.store.upsert_monthly_active_user = Mock(return_value=make_awaitable(None))  # type: ignore[assignment]
 
         self.store.is_trial_user = Mock(return_value=make_awaitable(False))  # type: ignore[assignment]
@@ -286,7 +286,7 @@ def test_populate_monthly_users_should_not_update(self):
 
         self.store.upsert_monthly_active_user.assert_not_called()
 
-    def test_get_reserved_real_user_account(self):
+    def test_get_reserved_real_user_account(self) -> None:
         # Test no reserved users, or reserved threepids
         users = self.get_success(self.store.get_registered_reserved_users())
         self.assertEqual(len(users), 0)
@@ -326,7 +326,7 @@ def test_get_reserved_real_user_account(self):
         users = self.get_success(self.store.get_registered_reserved_users())
         self.assertEqual(len(users), len(threepids))
 
-    def test_support_user_not_add_to_mau_limits(self):
+    def test_support_user_not_add_to_mau_limits(self) -> None:
         support_user_id = "@support:test"
 
         count = self.get_success(self.store.get_monthly_active_count())
@@ -347,7 +347,7 @@ def test_support_user_not_add_to_mau_limits(self):
     @override_config(
         {"limit_usage_by_mau": False, "mau_stats_only": True, "max_mau_value": 1}
     )
-    def test_track_monthly_users_without_cap(self):
+    def test_track_monthly_users_without_cap(self) -> None:
         count = self.get_success(self.store.get_monthly_active_count())
         self.assertEqual(0, count)
 
@@ -358,14 +358,14 @@ def test_track_monthly_users_without_cap(self):
         self.assertEqual(2, count)
 
     @override_config({"limit_usage_by_mau": False, "mau_stats_only": False})
-    def test_no_users_when_not_tracking(self):
+    def test_no_users_when_not_tracking(self) -> None:
         self.store.upsert_monthly_active_user = Mock(return_value=make_awaitable(None))  # type: ignore[assignment]
 
         self.get_success(self.store.populate_monthly_active_users("@user:sever"))
 
         self.store.upsert_monthly_active_user.assert_not_called()
 
-    def test_get_monthly_active_count_by_service(self):
+    def test_get_monthly_active_count_by_service(self) -> None:
         appservice1_user1 = "@appservice1_user1:example.com"
         appservice1_user2 = "@appservice1_user2:example.com"
 
@@ -413,7 +413,7 @@ def test_get_monthly_active_count_by_service(self):
         self.assertEqual(result[service2], 1)
         self.assertEqual(result[native], 1)
 
-    def test_get_monthly_active_users_by_service(self):
+    def test_get_monthly_active_users_by_service(self) -> None:
         # (No users, no filtering) -> empty result
         result = self.get_success(self.store.get_monthly_active_users_by_service())
 
diff --git a/tests/storage/test_purge.py b/tests/storage/test_purge.py
index 9c1182ed16b5..010cc74c3164 100644
--- a/tests/storage/test_purge.py
+++ b/tests/storage/test_purge.py
@@ -12,8 +12,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from twisted.test.proto_helpers import MemoryReactor
+
 from synapse.api.errors import NotFoundError, SynapseError
 from synapse.rest.client import room
+from synapse.server import HomeServer
+from synapse.util import Clock
 
 from tests.unittest import HomeserverTestCase
 
@@ -23,17 +27,17 @@ class PurgeTests(HomeserverTestCase):
     user_id = "@red:server"
     servlets = [room.register_servlets]
 
-    def make_homeserver(self, reactor, clock):
+    def make_homeserver(self, reactor: MemoryReactor, clock: Clock) -> HomeServer:
         hs = self.setup_test_homeserver("server", federation_http_client=None)
         return hs
 
-    def prepare(self, reactor, clock, hs):
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         self.room_id = self.helper.create_room_as(self.user_id)
 
         self.store = hs.get_datastores().main
         self._storage_controllers = self.hs.get_storage_controllers()
 
-    def test_purge_history(self):
+    def test_purge_history(self) -> None:
         """
         Purging a room history will delete everything before the topological point.
         """
@@ -63,7 +67,7 @@ def test_purge_history(self):
         self.get_failure(self.store.get_event(third["event_id"]), NotFoundError)
         self.get_success(self.store.get_event(last["event_id"]))
 
-    def test_purge_history_wont_delete_extrems(self):
+    def test_purge_history_wont_delete_extrems(self) -> None:
         """
         Purging a room history will delete everything before the topological point.
         """
@@ -77,6 +81,7 @@ def test_purge_history_wont_delete_extrems(self):
         token = self.get_success(
             self.store.get_topological_token_for_event(last["event_id"])
         )
+        assert token.topological is not None
         event = f"t{token.topological + 1}-{token.stream + 1}"
 
         # Purge everything before this topological token
@@ -94,7 +99,7 @@ def test_purge_history_wont_delete_extrems(self):
         self.get_success(self.store.get_event(third["event_id"]))
         self.get_success(self.store.get_event(last["event_id"]))
 
-    def test_purge_room(self):
+    def test_purge_room(self) -> None:
         """
         Purging a room will delete everything about it.
         """
diff --git a/tests/storage/test_receipts.py b/tests/storage/test_receipts.py
index 81253d0361d3..d8d84152dc5d 100644
--- a/tests/storage/test_receipts.py
+++ b/tests/storage/test_receipts.py
@@ -14,8 +14,12 @@
 
 from typing import Collection, Optional
 
+from twisted.test.proto_helpers import MemoryReactor
+
 from synapse.api.constants import ReceiptTypes
+from synapse.server import HomeServer
 from synapse.types import UserID, create_requester
+from synapse.util import Clock
 
 from tests.test_utils.event_injection import create_event
 from tests.unittest import HomeserverTestCase
@@ -25,7 +29,9 @@
 
 
 class ReceiptTestCase(HomeserverTestCase):
-    def prepare(self, reactor, clock, homeserver) -> None:
+    def prepare(
+        self, reactor: MemoryReactor, clock: Clock, homeserver: HomeServer
+    ) -> None:
         super().prepare(reactor, clock, homeserver)
 
         self.store = homeserver.get_datastores().main
@@ -135,11 +141,11 @@ def test_return_empty_with_no_data(self) -> None:
         )
         self.assertEqual(res, {})
 
-        res = self.get_last_unthreaded_receipt(
+        res2 = self.get_last_unthreaded_receipt(
             [ReceiptTypes.READ, ReceiptTypes.READ_PRIVATE]
         )
 
-        self.assertEqual(res, None)
+        self.assertIsNone(res2)
 
     def test_get_receipts_for_user(self) -> None:
         # Send some events into the first room
diff --git a/tests/storage/test_redaction.py b/tests/storage/test_redaction.py
index 6c4e63b77cac..df4740f9d9f2 100644
--- a/tests/storage/test_redaction.py
+++ b/tests/storage/test_redaction.py
@@ -11,27 +11,35 @@
 # 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.
-from typing import List, Optional
+from typing import List, Optional, cast
 
 from canonicaljson import json
 
+from twisted.test.proto_helpers import MemoryReactor
+
 from synapse.api.constants import EventTypes, Membership
 from synapse.api.room_versions import RoomVersions
-from synapse.types import RoomID, UserID
+from synapse.events import EventBase, _EventInternalMetadata
+from synapse.events.builder import EventBuilder
+from synapse.server import HomeServer
+from synapse.types import JsonDict, RoomID, UserID
+from synapse.util import Clock
 
 from tests import unittest
 from tests.utils import create_room
 
 
 class RedactionTestCase(unittest.HomeserverTestCase):
-    def default_config(self):
+    def default_config(self) -> JsonDict:
         config = super().default_config()
         config["redaction_retention_period"] = "30d"
         return config
 
-    def prepare(self, reactor, clock, hs):
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         self.store = hs.get_datastores().main
-        self._storage = hs.get_storage_controllers()
+        storage = hs.get_storage_controllers()
+        assert storage.persistence is not None
+        self._persistence = storage.persistence
         self.event_builder_factory = hs.get_event_builder_factory()
         self.event_creation_handler = hs.get_event_creation_handler()
 
@@ -46,14 +54,13 @@ def prepare(self, reactor, clock, hs):
 
         self.depth = 1
 
-    def inject_room_member(
+    def inject_room_member(  # type: ignore[override]
         self,
-        room,
-        user,
-        membership,
-        replaces_state=None,
-        extra_content: Optional[dict] = None,
-    ):
+        room: RoomID,
+        user: UserID,
+        membership: str,
+        extra_content: Optional[JsonDict] = None,
+    ) -> EventBase:
         content = {"membership": membership}
         content.update(extra_content or {})
         builder = self.event_builder_factory.for_room_version(
@@ -71,11 +78,11 @@ def inject_room_member(
             self.event_creation_handler.create_new_client_event(builder)
         )
 
-        self.get_success(self._storage.persistence.persist_event(event, context))
+        self.get_success(self._persistence.persist_event(event, context))
 
         return event
 
-    def inject_message(self, room, user, body):
+    def inject_message(self, room: RoomID, user: UserID, body: str) -> EventBase:
         self.depth += 1
 
         builder = self.event_builder_factory.for_room_version(
@@ -93,11 +100,13 @@ def inject_message(self, room, user, body):
             self.event_creation_handler.create_new_client_event(builder)
         )
 
-        self.get_success(self._storage.persistence.persist_event(event, context))
+        self.get_success(self._persistence.persist_event(event, context))
 
         return event
 
-    def inject_redaction(self, room, event_id, user, reason):
+    def inject_redaction(
+        self, room: RoomID, event_id: str, user: UserID, reason: str
+    ) -> EventBase:
         builder = self.event_builder_factory.for_room_version(
             RoomVersions.V1,
             {
@@ -114,11 +123,11 @@ def inject_redaction(self, room, event_id, user, reason):
             self.event_creation_handler.create_new_client_event(builder)
         )
 
-        self.get_success(self._storage.persistence.persist_event(event, context))
+        self.get_success(self._persistence.persist_event(event, context))
 
         return event
 
-    def test_redact(self):
+    def test_redact(self) -> None:
         self.inject_room_member(self.room1, self.u_alice, Membership.JOIN)
 
         msg_event = self.inject_message(self.room1, self.u_alice, "t")
@@ -165,7 +174,7 @@ def test_redact(self):
             event.unsigned["redacted_because"],
         )
 
-    def test_redact_join(self):
+    def test_redact_join(self) -> None:
         self.inject_room_member(self.room1, self.u_alice, Membership.JOIN)
 
         msg_event = self.inject_room_member(
@@ -213,12 +222,12 @@ def test_redact_join(self):
             event.unsigned["redacted_because"],
         )
 
-    def test_circular_redaction(self):
+    def test_circular_redaction(self) -> None:
         redaction_event_id1 = "$redaction1_id:test"
         redaction_event_id2 = "$redaction2_id:test"
 
         class EventIdManglingBuilder:
-            def __init__(self, base_builder, event_id):
+            def __init__(self, base_builder: EventBuilder, event_id: str):
                 self._base_builder = base_builder
                 self._event_id = event_id
 
@@ -227,67 +236,73 @@ async def build(
                 prev_event_ids: List[str],
                 auth_event_ids: Optional[List[str]],
                 depth: Optional[int] = None,
-            ):
+            ) -> EventBase:
                 built_event = await self._base_builder.build(
                     prev_event_ids=prev_event_ids, auth_event_ids=auth_event_ids
                 )
 
-                built_event._event_id = self._event_id
+                built_event._event_id = self._event_id  # type: ignore[attr-defined]
                 built_event._dict["event_id"] = self._event_id
                 assert built_event.event_id == self._event_id
 
                 return built_event
 
             @property
-            def room_id(self):
+            def room_id(self) -> str:
                 return self._base_builder.room_id
 
             @property
-            def type(self):
+            def type(self) -> str:
                 return self._base_builder.type
 
             @property
-            def internal_metadata(self):
+            def internal_metadata(self) -> _EventInternalMetadata:
                 return self._base_builder.internal_metadata
 
         event_1, context_1 = self.get_success(
             self.event_creation_handler.create_new_client_event(
-                EventIdManglingBuilder(
-                    self.event_builder_factory.for_room_version(
-                        RoomVersions.V1,
-                        {
-                            "type": EventTypes.Redaction,
-                            "sender": self.u_alice.to_string(),
-                            "room_id": self.room1.to_string(),
-                            "content": {"reason": "test"},
-                            "redacts": redaction_event_id2,
-                        },
+                cast(
+                    EventBuilder,
+                    EventIdManglingBuilder(
+                        self.event_builder_factory.for_room_version(
+                            RoomVersions.V1,
+                            {
+                                "type": EventTypes.Redaction,
+                                "sender": self.u_alice.to_string(),
+                                "room_id": self.room1.to_string(),
+                                "content": {"reason": "test"},
+                                "redacts": redaction_event_id2,
+                            },
+                        ),
+                        redaction_event_id1,
                     ),
-                    redaction_event_id1,
                 )
             )
         )
 
-        self.get_success(self._storage.persistence.persist_event(event_1, context_1))
+        self.get_success(self._persistence.persist_event(event_1, context_1))
 
         event_2, context_2 = self.get_success(
             self.event_creation_handler.create_new_client_event(
-                EventIdManglingBuilder(
-                    self.event_builder_factory.for_room_version(
-                        RoomVersions.V1,
-                        {
-                            "type": EventTypes.Redaction,
-                            "sender": self.u_alice.to_string(),
-                            "room_id": self.room1.to_string(),
-                            "content": {"reason": "test"},
-                            "redacts": redaction_event_id1,
-                        },
+                cast(
+                    EventBuilder,
+                    EventIdManglingBuilder(
+                        self.event_builder_factory.for_room_version(
+                            RoomVersions.V1,
+                            {
+                                "type": EventTypes.Redaction,
+                                "sender": self.u_alice.to_string(),
+                                "room_id": self.room1.to_string(),
+                                "content": {"reason": "test"},
+                                "redacts": redaction_event_id1,
+                            },
+                        ),
+                        redaction_event_id2,
                     ),
-                    redaction_event_id2,
                 )
             )
         )
-        self.get_success(self._storage.persistence.persist_event(event_2, context_2))
+        self.get_success(self._persistence.persist_event(event_2, context_2))
 
         # fetch one of the redactions
         fetched = self.get_success(self.store.get_event(redaction_event_id1))
@@ -298,7 +313,7 @@ def internal_metadata(self):
             fetched.unsigned["redacted_because"].event_id, redaction_event_id2
         )
 
-    def test_redact_censor(self):
+    def test_redact_censor(self) -> None:
         """Test that a redacted event gets censored in the DB after a month"""
 
         self.inject_room_member(self.room1, self.u_alice, Membership.JOIN)
@@ -364,7 +379,7 @@ def test_redact_censor(self):
 
         self.assert_dict({"content": {}}, json.loads(event_json))
 
-    def test_redact_redaction(self):
+    def test_redact_redaction(self) -> None:
         """Tests that we can redact a redaction and can fetch it again."""
 
         self.inject_room_member(self.room1, self.u_alice, Membership.JOIN)
@@ -391,7 +406,7 @@ def test_redact_redaction(self):
             self.store.get_event(first_redact_event.event_id, allow_none=True)
         )
 
-    def test_store_redacted_redaction(self):
+    def test_store_redacted_redaction(self) -> None:
         """Tests that we can store a redacted redaction."""
 
         self.inject_room_member(self.room1, self.u_alice, Membership.JOIN)
@@ -410,9 +425,7 @@ def test_store_redacted_redaction(self):
             self.event_creation_handler.create_new_client_event(builder)
         )
 
-        self.get_success(
-            self._storage.persistence.persist_event(redaction_event, context)
-        )
+        self.get_success(self._persistence.persist_event(redaction_event, context))
 
         # Now lets jump to the future where we have censored the redaction event
         # in the DB.
diff --git a/tests/storage/test_rollback_worker.py b/tests/storage/test_rollback_worker.py
index 0baa54312e33..966aafea6fd3 100644
--- a/tests/storage/test_rollback_worker.py
+++ b/tests/storage/test_rollback_worker.py
@@ -14,10 +14,15 @@
 from typing import List
 from unittest import mock
 
+from twisted.test.proto_helpers import MemoryReactor
+
 from synapse.app.generic_worker import GenericWorkerServer
+from synapse.server import HomeServer
 from synapse.storage.database import LoggingDatabaseConnection
 from synapse.storage.prepare_database import PrepareDatabaseException, prepare_database
 from synapse.storage.schema import SCHEMA_VERSION
+from synapse.types import JsonDict
+from synapse.util import Clock
 
 from tests.unittest import HomeserverTestCase
 
@@ -39,13 +44,13 @@ def fake_listdir(filepath: str) -> List[str]:
 
 
 class WorkerSchemaTests(HomeserverTestCase):
-    def make_homeserver(self, reactor, clock):
+    def make_homeserver(self, reactor: MemoryReactor, clock: Clock) -> HomeServer:
         hs = self.setup_test_homeserver(
             federation_http_client=None, homeserver_to_use=GenericWorkerServer
         )
         return hs
 
-    def default_config(self):
+    def default_config(self) -> JsonDict:
         conf = super().default_config()
 
         # Mark this as a worker app.
@@ -53,7 +58,7 @@ def default_config(self):
 
         return conf
 
-    def test_rolling_back(self):
+    def test_rolling_back(self) -> None:
         """Test that workers can start if the DB is a newer schema version"""
 
         db_pool = self.hs.get_datastores().main.db_pool
@@ -70,7 +75,7 @@ def test_rolling_back(self):
 
         prepare_database(db_conn, db_pool.engine, self.hs.config)
 
-    def test_not_upgraded_old_schema_version(self):
+    def test_not_upgraded_old_schema_version(self) -> None:
         """Test that workers don't start if the DB has an older schema version"""
         db_pool = self.hs.get_datastores().main.db_pool
         db_conn = LoggingDatabaseConnection(
@@ -87,7 +92,7 @@ def test_not_upgraded_old_schema_version(self):
         with self.assertRaises(PrepareDatabaseException):
             prepare_database(db_conn, db_pool.engine, self.hs.config)
 
-    def test_not_upgraded_current_schema_version_with_outstanding_deltas(self):
+    def test_not_upgraded_current_schema_version_with_outstanding_deltas(self) -> None:
         """
         Test that workers don't start if the DB is on the current schema version,
         but there are still outstanding delta migrations to run.
diff --git a/tests/storage/test_room.py b/tests/storage/test_room.py
index 3405efb6a8e8..71ec74eadc91 100644
--- a/tests/storage/test_room.py
+++ b/tests/storage/test_room.py
@@ -12,14 +12,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from twisted.test.proto_helpers import MemoryReactor
+
 from synapse.api.room_versions import RoomVersions
+from synapse.server import HomeServer
 from synapse.types import RoomAlias, RoomID, UserID
+from synapse.util import Clock
 
 from tests.unittest import HomeserverTestCase
 
 
 class RoomStoreTestCase(HomeserverTestCase):
-    def prepare(self, reactor, clock, hs):
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         # We can't test RoomStore on its own without the DirectoryStore, for
         # management of the 'room_aliases' table
         self.store = hs.get_datastores().main
@@ -37,30 +41,34 @@ def prepare(self, reactor, clock, hs):
             )
         )
 
-    def test_get_room(self):
+    def test_get_room(self) -> None:
+        res = self.get_success(self.store.get_room(self.room.to_string()))
+        assert res is not None
         self.assertDictContainsSubset(
             {
                 "room_id": self.room.to_string(),
                 "creator": self.u_creator.to_string(),
                 "is_public": True,
             },
-            (self.get_success(self.store.get_room(self.room.to_string()))),
+            res,
         )
 
-    def test_get_room_unknown_room(self):
+    def test_get_room_unknown_room(self) -> None:
         self.assertIsNone(self.get_success(self.store.get_room("!uknown:test")))
 
-    def test_get_room_with_stats(self):
+    def test_get_room_with_stats(self) -> None:
+        res = self.get_success(self.store.get_room_with_stats(self.room.to_string()))
+        assert res is not None
         self.assertDictContainsSubset(
             {
                 "room_id": self.room.to_string(),
                 "creator": self.u_creator.to_string(),
                 "public": True,
             },
-            (self.get_success(self.store.get_room_with_stats(self.room.to_string()))),
+            res,
         )
 
-    def test_get_room_with_stats_unknown_room(self):
+    def test_get_room_with_stats_unknown_room(self) -> None:
         self.assertIsNone(
-            (self.get_success(self.store.get_room_with_stats("!uknown:test"))),
+            self.get_success(self.store.get_room_with_stats("!uknown:test"))
         )
diff --git a/tests/storage/test_room_search.py b/tests/storage/test_room_search.py
index ef850daa73d7..14d872514d21 100644
--- a/tests/storage/test_room_search.py
+++ b/tests/storage/test_room_search.py
@@ -39,7 +39,7 @@ class EventSearchInsertionTest(HomeserverTestCase):
         room.register_servlets,
     ]
 
-    def test_null_byte(self):
+    def test_null_byte(self) -> None:
         """
         Postgres/SQLite don't like null bytes going into the search tables. Internally
         we replace those with a space.
@@ -86,7 +86,7 @@ def test_null_byte(self):
         if isinstance(store.database_engine, PostgresEngine):
             self.assertIn("alice", result.get("highlights"))
 
-    def test_non_string(self):
+    def test_non_string(self) -> None:
         """Test that non-string `value`s are not inserted into `event_search`.
 
         This is particularly important when using sqlite, since a sqlite column can hold
@@ -157,7 +157,7 @@ def test_non_string(self):
         self.assertEqual(f.value.code, 404)
 
     @skip_unless(not USE_POSTGRES_FOR_TESTS, "requires sqlite")
-    def test_sqlite_non_string_deletion_background_update(self):
+    def test_sqlite_non_string_deletion_background_update(self) -> None:
         """Test the background update to delete bad rows from `event_search`."""
         store = self.hs.get_datastores().main
 
@@ -350,7 +350,7 @@ def _check_test_cases(
                 "results array length should match count",
             )
 
-    def test_postgres_web_search_for_phrase(self):
+    def test_postgres_web_search_for_phrase(self) -> None:
         """
         Test searching for phrases using typical web search syntax, as per postgres' websearch_to_tsquery.
         This test is skipped unless the postgres instance supports websearch_to_tsquery.
@@ -364,7 +364,7 @@ def test_postgres_web_search_for_phrase(self):
 
         self._check_test_cases(store, self.COMMON_CASES + self.POSTGRES_CASES)
 
-    def test_sqlite_search(self):
+    def test_sqlite_search(self) -> None:
         """
         Test sqlite searching for phrases.
         """
diff --git a/tests/storage/test_state.py b/tests/storage/test_state.py
index 5564161750e6..d4e6d4236c10 100644
--- a/tests/storage/test_state.py
+++ b/tests/storage/test_state.py
@@ -16,10 +16,15 @@
 
 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.storage.state import StateFilter
-from synapse.types import RoomID, UserID
+from synapse.types import JsonDict, RoomID, StateMap, UserID
+from synapse.util import Clock
 
 from tests.unittest import HomeserverTestCase, TestCase
 
@@ -27,7 +32,7 @@
 
 
 class StateStoreTestCase(HomeserverTestCase):
-    def prepare(self, reactor, clock, hs):
+    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
@@ -48,7 +53,9 @@ def prepare(self, reactor, clock, hs):
             )
         )
 
-    def inject_state_event(self, room, sender, typ, state_key, content):
+    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,
             {
@@ -64,24 +71,29 @@ def inject_state_event(self, room, sender, typ, state_key, content):
             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, s2):
+    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):
+    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, [e2.event_id])
+            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]
@@ -90,21 +102,21 @@ def test_get_state_groups_ids(self):
             {(EventTypes.Create, ""): e1.event_id, (EventTypes.Name, ""): e2.event_id},
         )
 
-    def test_get_state_groups(self):
+    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, [e2.event_id])
+            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):
+    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, "", {})
@@ -487,14 +499,16 @@ def test_get_state_for_event(self):
 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):
+    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
@@ -610,7 +624,7 @@ def test_state_filter_difference_no_include_other_minus_no_include_other(self):
             ),
         )
 
-    def test_state_filter_difference_include_other_minus_no_include_other(self):
+    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.
@@ -739,7 +753,7 @@ def test_state_filter_difference_include_other_minus_no_include_other(self):
             ),
         )
 
-    def test_state_filter_difference_include_other_minus_include_other(self):
+    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
@@ -864,7 +878,7 @@ def test_state_filter_difference_include_other_minus_include_other(self):
             ),
         )
 
-    def test_state_filter_difference_no_include_other_minus_include_other(self):
+    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.
@@ -979,7 +993,7 @@ def test_state_filter_difference_no_include_other_minus_include_other(self):
             ),
         )
 
-    def test_state_filter_difference_simple_cases(self):
+    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.
@@ -995,7 +1009,7 @@ def test_state_filter_difference_simple_cases(self):
 
 
 class StateFilterTestCase(TestCase):
-    def test_return_expanded(self):
+    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).
diff --git a/tests/storage/test_stream.py b/tests/storage/test_stream.py
index 34fa810cf61a..bc090ebce039 100644
--- a/tests/storage/test_stream.py
+++ b/tests/storage/test_stream.py
@@ -14,11 +14,15 @@
 
 from typing import List
 
+from twisted.test.proto_helpers import MemoryReactor
+
 from synapse.api.constants import EventTypes, RelationTypes
 from synapse.api.filtering import Filter
 from synapse.rest import admin
 from synapse.rest.client import login, room
+from synapse.server import HomeServer
 from synapse.types import JsonDict
+from synapse.util import Clock
 
 from tests.unittest import HomeserverTestCase
 
@@ -37,12 +41,14 @@ class PaginationTestCase(HomeserverTestCase):
         login.register_servlets,
     ]
 
-    def default_config(self):
+    def default_config(self) -> JsonDict:
         config = super().default_config()
         config["experimental_features"] = {"msc3874_enabled": True}
         return config
 
-    def prepare(self, reactor, clock, homeserver):
+    def prepare(
+        self, reactor: MemoryReactor, clock: Clock, homeserver: HomeServer
+    ) -> None:
         self.user_id = self.register_user("test", "test")
         self.tok = self.login("test", "test")
         self.room_id = self.helper.create_room_as(self.user_id, tok=self.tok)
@@ -130,7 +136,7 @@ def _filter_messages(self, filter: JsonDict) -> List[str]:
 
         return [ev.event_id for ev in events]
 
-    def test_filter_relation_senders(self):
+    def test_filter_relation_senders(self) -> None:
         # Messages which second user reacted to.
         filter = {"related_by_senders": [self.second_user_id]}
         chunk = self._filter_messages(filter)
@@ -146,7 +152,7 @@ def test_filter_relation_senders(self):
         chunk = self._filter_messages(filter)
         self.assertCountEqual(chunk, [self.event_id_1, self.event_id_2])
 
-    def test_filter_relation_type(self):
+    def test_filter_relation_type(self) -> None:
         # Messages which have annotations.
         filter = {"related_by_rel_types": [RelationTypes.ANNOTATION]}
         chunk = self._filter_messages(filter)
@@ -167,7 +173,7 @@ def test_filter_relation_type(self):
         chunk = self._filter_messages(filter)
         self.assertCountEqual(chunk, [self.event_id_1, self.event_id_2])
 
-    def test_filter_relation_senders_and_type(self):
+    def test_filter_relation_senders_and_type(self) -> None:
         # Messages which second user reacted to.
         filter = {
             "related_by_senders": [self.second_user_id],
@@ -176,7 +182,7 @@ def test_filter_relation_senders_and_type(self):
         chunk = self._filter_messages(filter)
         self.assertEqual(chunk, [self.event_id_1])
 
-    def test_duplicate_relation(self):
+    def test_duplicate_relation(self) -> None:
         """An event should only be returned once if there are multiple relations to it."""
         self.helper.send_event(
             room_id=self.room_id,
diff --git a/tests/storage/test_transactions.py b/tests/storage/test_transactions.py
index e05daa285e4c..db9ee9955e93 100644
--- a/tests/storage/test_transactions.py
+++ b/tests/storage/test_transactions.py
@@ -12,17 +12,23 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from twisted.test.proto_helpers import MemoryReactor
+
+from synapse.server import HomeServer
 from synapse.storage.databases.main.transactions import DestinationRetryTimings
+from synapse.util import Clock
 from synapse.util.retryutils import MAX_RETRY_INTERVAL
 
 from tests.unittest import HomeserverTestCase
 
 
 class TransactionStoreTestCase(HomeserverTestCase):
-    def prepare(self, reactor, clock, homeserver):
+    def prepare(
+        self, reactor: MemoryReactor, clock: Clock, homeserver: HomeServer
+    ) -> None:
         self.store = homeserver.get_datastores().main
 
-    def test_get_set_transactions(self):
+    def test_get_set_transactions(self) -> None:
         """Tests that we can successfully get a non-existent entry for
         destination retries, as well as testing tht we can set and get
         correctly.
@@ -44,18 +50,18 @@ def test_get_set_transactions(self):
             r,
         )
 
-    def test_initial_set_transactions(self):
+    def test_initial_set_transactions(self) -> None:
         """Tests that we can successfully set the destination retries (there
         was a bug around invalidating the cache that broke this)
         """
         d = self.store.set_destination_retry_timings("example.com", 1000, 50, 100)
         self.get_success(d)
 
-    def test_large_destination_retry(self):
+    def test_large_destination_retry(self) -> None:
         d = self.store.set_destination_retry_timings(
             "example.com", MAX_RETRY_INTERVAL, MAX_RETRY_INTERVAL, MAX_RETRY_INTERVAL
         )
         self.get_success(d)
 
-        d = self.store.get_destination_retry_timings("example.com")
-        self.get_success(d)
+        d2 = self.store.get_destination_retry_timings("example.com")
+        self.get_success(d2)
diff --git a/tests/storage/test_txn_limit.py b/tests/storage/test_txn_limit.py
index ace82cbf420f..15ea4770bd7e 100644
--- a/tests/storage/test_txn_limit.py
+++ b/tests/storage/test_txn_limit.py
@@ -12,21 +12,27 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from twisted.test.proto_helpers import MemoryReactor
+
+from synapse.server import HomeServer
+from synapse.storage.types import Cursor
+from synapse.util import Clock
+
 from tests import unittest
 
 
 class SQLTransactionLimitTestCase(unittest.HomeserverTestCase):
     """Test SQL transaction limit doesn't break transactions."""
 
-    def make_homeserver(self, reactor, clock):
+    def make_homeserver(self, reactor: MemoryReactor, clock: Clock) -> HomeServer:
         return self.setup_test_homeserver(db_txn_limit=1000)
 
-    def test_config(self):
+    def test_config(self) -> None:
         db_config = self.hs.config.database.get_single_database()
         self.assertEqual(db_config.config["txn_limit"], 1000)
 
-    def test_select(self):
-        def do_select(txn):
+    def test_select(self) -> None:
+        def do_select(txn: Cursor) -> None:
             txn.execute("SELECT 1")
 
         db_pool = self.hs.get_datastores().databases[0]
diff --git a/tests/storage/util/test_partial_state_events_tracker.py b/tests/storage/util/test_partial_state_events_tracker.py
index cae14151c0fa..0e3fc2a77f05 100644
--- a/tests/storage/util/test_partial_state_events_tracker.py
+++ b/tests/storage/util/test_partial_state_events_tracker.py
@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from typing import Dict
+from typing import Collection, Dict
 from unittest import mock
 
 from twisted.internet.defer import CancelledError, ensureDeferred
@@ -31,7 +31,7 @@ def setUp(self) -> None:
         # the results to be returned by the mocked get_partial_state_events
         self._events_dict: Dict[str, bool] = {}
 
-        async def get_partial_state_events(events):
+        async def get_partial_state_events(events: Collection[str]) -> Dict[str, bool]:
             return {e: self._events_dict[e] for e in events}
 
         self.mock_store = mock.Mock(spec_set=["get_partial_state_events"])
@@ -39,7 +39,7 @@ async def get_partial_state_events(events):
 
         self.tracker = PartialStateEventsTracker(self.mock_store)
 
-    def test_does_not_block_for_full_state_events(self):
+    def test_does_not_block_for_full_state_events(self) -> None:
         self._events_dict = {"event1": False, "event2": False}
 
         self.successResultOf(
@@ -50,7 +50,7 @@ def test_does_not_block_for_full_state_events(self):
             ["event1", "event2"]
         )
 
-    def test_blocks_for_partial_state_events(self):
+    def test_blocks_for_partial_state_events(self) -> None:
         self._events_dict = {"event1": True, "event2": False}
 
         d = ensureDeferred(self.tracker.await_full_state(["event1", "event2"]))
@@ -62,12 +62,12 @@ def test_blocks_for_partial_state_events(self):
         self.tracker.notify_un_partial_stated("event1")
         self.successResultOf(d)
 
-    def test_un_partial_state_race(self):
+    def test_un_partial_state_race(self) -> None:
         # if the event is un-partial-stated between the initial check and the
         # registration of the listener, it should not block.
         self._events_dict = {"event1": True, "event2": False}
 
-        async def get_partial_state_events(events):
+        async def get_partial_state_events(events: Collection[str]) -> Dict[str, bool]:
             res = {e: self._events_dict[e] for e in events}
             # change the result for next time
             self._events_dict = {"event1": False, "event2": False}
@@ -79,19 +79,19 @@ async def get_partial_state_events(events):
             ensureDeferred(self.tracker.await_full_state(["event1", "event2"]))
         )
 
-    def test_un_partial_state_during_get_partial_state_events(self):
+    def test_un_partial_state_during_get_partial_state_events(self) -> None:
         # we should correctly handle a call to notify_un_partial_stated during the
         # second call to get_partial_state_events.
 
         self._events_dict = {"event1": True, "event2": False}
 
-        async def get_partial_state_events1(events):
+        async def get_partial_state_events1(events: Collection[str]) -> Dict[str, bool]:
             self.mock_store.get_partial_state_events.side_effect = (
                 get_partial_state_events2
             )
             return {e: self._events_dict[e] for e in events}
 
-        async def get_partial_state_events2(events):
+        async def get_partial_state_events2(events: Collection[str]) -> Dict[str, bool]:
             self.tracker.notify_un_partial_stated("event1")
             self._events_dict["event1"] = False
             return {e: self._events_dict[e] for e in events}
@@ -102,7 +102,7 @@ async def get_partial_state_events2(events):
             ensureDeferred(self.tracker.await_full_state(["event1", "event2"]))
         )
 
-    def test_cancellation(self):
+    def test_cancellation(self) -> None:
         self._events_dict = {"event1": True, "event2": False}
 
         d1 = ensureDeferred(self.tracker.await_full_state(["event1", "event2"]))
@@ -127,12 +127,12 @@ def setUp(self) -> None:
 
         self.tracker = PartialCurrentStateTracker(self.mock_store)
 
-    def test_does_not_block_for_full_state_rooms(self):
+    def test_does_not_block_for_full_state_rooms(self) -> None:
         self.mock_store.is_partial_state_room.return_value = make_awaitable(False)
 
         self.successResultOf(ensureDeferred(self.tracker.await_full_state("room_id")))
 
-    def test_blocks_for_partial_room_state(self):
+    def test_blocks_for_partial_room_state(self) -> None:
         self.mock_store.is_partial_state_room.return_value = make_awaitable(True)
 
         d = ensureDeferred(self.tracker.await_full_state("room_id"))
@@ -144,10 +144,10 @@ def test_blocks_for_partial_room_state(self):
         self.tracker.notify_un_partial_stated("room_id")
         self.successResultOf(d)
 
-    def test_un_partial_state_race(self):
+    def test_un_partial_state_race(self) -> None:
         # We should correctly handle race between awaiting the state and us
         # un-partialling the state
-        async def is_partial_state_room(events):
+        async def is_partial_state_room(room_id: str) -> bool:
             self.tracker.notify_un_partial_stated("room_id")
             return True
 
@@ -155,7 +155,7 @@ async def is_partial_state_room(events):
 
         self.successResultOf(ensureDeferred(self.tracker.await_full_state("room_id")))
 
-    def test_cancellation(self):
+    def test_cancellation(self) -> None:
         self.mock_store.is_partial_state_room.return_value = make_awaitable(True)
 
         d1 = ensureDeferred(self.tracker.await_full_state("room_id"))