diff --git a/changelog.d/10347.misc b/changelog.d/10347.misc
new file mode 100644
index 000000000000..b2275a1350b9
--- /dev/null
+++ b/changelog.d/10347.misc
@@ -0,0 +1 @@
+Run `pyupgrade` on the codebase.
\ No newline at end of file
diff --git a/tests/config/test_load.py b/tests/config/test_load.py
index ebe2c0516570..903c69127d13 100644
--- a/tests/config/test_load.py
+++ b/tests/config/test_load.py
@@ -43,7 +43,7 @@ def test_load_fails_if_server_name_missing(self):
     def test_generates_and_loads_macaroon_secret_key(self):
         self.generate_config()
 
-        with open(self.file, "r") as f:
+        with open(self.file) as f:
             raw = yaml.safe_load(f)
         self.assertIn("macaroon_secret_key", raw)
 
@@ -120,7 +120,7 @@ def generate_config(self):
     def generate_config_and_remove_lines_containing(self, needle):
         self.generate_config()
 
-        with open(self.file, "r") as f:
+        with open(self.file) as f:
             contents = f.readlines()
         contents = [line for line in contents if needle not in line]
         with open(self.file, "w") as f:
diff --git a/tests/handlers/test_profile.py b/tests/handlers/test_profile.py
index cdb41101b3c4..2928c4f48cca 100644
--- a/tests/handlers/test_profile.py
+++ b/tests/handlers/test_profile.py
@@ -103,7 +103,7 @@ def test_set_my_name(self):
         )
 
         self.assertIsNone(
-            (self.get_success(self.store.get_profile_displayname(self.frank.localpart)))
+            self.get_success(self.store.get_profile_displayname(self.frank.localpart))
         )
 
     def test_set_my_name_if_disabled(self):
diff --git a/tests/http/federation/test_matrix_federation_agent.py b/tests/http/federation/test_matrix_federation_agent.py
index e45980316b6d..a37bce08c33a 100644
--- a/tests/http/federation/test_matrix_federation_agent.py
+++ b/tests/http/federation/test_matrix_federation_agent.py
@@ -273,7 +273,7 @@ def test_get(self):
         self.assertEqual(response.code, 200)
 
         # Send the body
-        request.write('{ "a": 1 }'.encode("ascii"))
+        request.write(b'{ "a": 1 }')
         request.finish()
 
         self.reactor.pump((0.1,))
diff --git a/tests/http/test_fedclient.py b/tests/http/test_fedclient.py
index ed9a884d761b..d9a8b077d390 100644
--- a/tests/http/test_fedclient.py
+++ b/tests/http/test_fedclient.py
@@ -102,7 +102,7 @@ def do_request():
         self.assertNoResult(test_d)
 
         # Send it the HTTP response
-        res_json = '{ "a": 1 }'.encode("ascii")
+        res_json = b'{ "a": 1 }'
         protocol.dataReceived(
             b"HTTP/1.1 200 OK\r\n"
             b"Server: Fake\r\n"
@@ -339,10 +339,8 @@ def test_timeout_reading_body(self, method_name: str):
 
         # Send it the HTTP response
         client.dataReceived(
-            (
-                b"HTTP/1.1 200 OK\r\nContent-Type: application/json\r\n"
-                b"Server: Fake\r\n\r\n"
-            )
+            b"HTTP/1.1 200 OK\r\nContent-Type: application/json\r\n"
+            b"Server: Fake\r\n\r\n"
         )
 
         # Push by enough to time it out
diff --git a/tests/replication/_base.py b/tests/replication/_base.py
index 624bd1b92722..386ea70a2596 100644
--- a/tests/replication/_base.py
+++ b/tests/replication/_base.py
@@ -550,12 +550,12 @@ def encode(self, obj):
         if obj is None:
             return "$-1\r\n"
         if isinstance(obj, str):
-            return "${len}\r\n{str}\r\n".format(len=len(obj), str=obj)
+            return f"${len(obj)}\r\n{obj}\r\n"
         if isinstance(obj, int):
-            return ":{val}\r\n".format(val=obj)
+            return f":{obj}\r\n"
         if isinstance(obj, (list, tuple)):
             items = "".join(self.encode(a) for a in obj)
-            return "*{len}\r\n{items}".format(len=len(obj), items=items)
+            return f"*{len(obj)}\r\n{items}"
 
         raise Exception("Unrecognized type for encoding redis: %r: %r", type(obj), obj)
 
diff --git a/tests/replication/test_multi_media_repo.py b/tests/replication/test_multi_media_repo.py
index 76e6644353d0..b42f1288eb7f 100644
--- a/tests/replication/test_multi_media_repo.py
+++ b/tests/replication/test_multi_media_repo.py
@@ -70,7 +70,7 @@ def _get_media_req(
             self.reactor,
             FakeSite(resource),
             "GET",
-            "/{}/{}".format(target, media_id),
+            f"/{target}/{media_id}",
             shorthand=False,
             access_token=self.access_token,
             await_result=False,
@@ -113,7 +113,7 @@ def _get_media_req(
         self.assertEqual(request.method, b"GET")
         self.assertEqual(
             request.path,
-            "/_matrix/media/r0/download/{}/{}".format(target, media_id).encode("utf-8"),
+            f"/_matrix/media/r0/download/{target}/{media_id}".encode("utf-8"),
         )
         self.assertEqual(
             request.requestHeaders.getRawHeaders(b"host"), [target.encode("utf-8")]
diff --git a/tests/replication/test_sharded_event_persister.py b/tests/replication/test_sharded_event_persister.py
index 5eca5c165d0a..f3615af97e86 100644
--- a/tests/replication/test_sharded_event_persister.py
+++ b/tests/replication/test_sharded_event_persister.py
@@ -211,7 +211,7 @@ def test_vector_clock_token(self):
             self.reactor,
             sync_hs_site,
             "GET",
-            "/sync?since={}".format(next_batch),
+            f"/sync?since={next_batch}",
             access_token=access_token,
         )
 
@@ -241,7 +241,7 @@ def test_vector_clock_token(self):
             self.reactor,
             sync_hs_site,
             "GET",
-            "/sync?since={}".format(vector_clock_token),
+            f"/sync?since={vector_clock_token}",
             access_token=access_token,
         )
 
@@ -266,7 +266,7 @@ def test_vector_clock_token(self):
             self.reactor,
             sync_hs_site,
             "GET",
-            "/sync?since={}".format(next_batch),
+            f"/sync?since={next_batch}",
             access_token=access_token,
         )
 
diff --git a/tests/rest/admin/test_admin.py b/tests/rest/admin/test_admin.py
index 2f7090e5543b..a7c6e595b983 100644
--- a/tests/rest/admin/test_admin.py
+++ b/tests/rest/admin/test_admin.py
@@ -66,7 +66,7 @@ def test_delete_group(self):
         # Create a new group
         channel = self.make_request(
             "POST",
-            "/create_group".encode("ascii"),
+            b"/create_group",
             access_token=self.admin_user_tok,
             content={"localpart": "test"},
         )
@@ -129,9 +129,7 @@ def _check_group(self, group_id, expect_code):
 
     def _get_groups_user_is_in(self, access_token):
         """Returns the list of groups the user is in (given their access token)"""
-        channel = self.make_request(
-            "GET", "/joined_groups".encode("ascii"), access_token=access_token
-        )
+        channel = self.make_request("GET", b"/joined_groups", access_token=access_token)
 
         self.assertEqual(200, int(channel.result["code"]), msg=channel.result["body"])
 
diff --git a/tests/rest/admin/test_room.py b/tests/rest/admin/test_room.py
index 959d3cea77e0..17ec8bfd3b93 100644
--- a/tests/rest/admin/test_room.py
+++ b/tests/rest/admin/test_room.py
@@ -535,7 +535,7 @@ def _is_purged(self, room_id):
                 )
             )
 
-            self.assertEqual(count, 0, msg="Rows not purged in {}".format(table))
+            self.assertEqual(count, 0, msg=f"Rows not purged in {table}")
 
     def _assert_peek(self, room_id, expect_code):
         """Assert that the admin user can (or cannot) peek into the room."""
@@ -599,7 +599,7 @@ def test_purge_room(self):
                 )
             )
 
-            self.assertEqual(count, 0, msg="Rows not purged in {}".format(table))
+            self.assertEqual(count, 0, msg=f"Rows not purged in {table}")
 
 
 class RoomTestCase(unittest.HomeserverTestCase):
@@ -1280,7 +1280,7 @@ def prepare(self, reactor, clock, homeserver):
         self.public_room_id = self.helper.create_room_as(
             self.creator, tok=self.creator_tok, is_public=True
         )
-        self.url = "/_synapse/admin/v1/join/{}".format(self.public_room_id)
+        self.url = f"/_synapse/admin/v1/join/{self.public_room_id}"
 
     def test_requester_is_no_admin(self):
         """
@@ -1420,7 +1420,7 @@ def test_join_private_room_if_not_member(self):
         private_room_id = self.helper.create_room_as(
             self.creator, tok=self.creator_tok, is_public=False
         )
-        url = "/_synapse/admin/v1/join/{}".format(private_room_id)
+        url = f"/_synapse/admin/v1/join/{private_room_id}"
         body = json.dumps({"user_id": self.second_user_id})
 
         channel = self.make_request(
@@ -1463,7 +1463,7 @@ def test_join_private_room_if_member(self):
 
         # Join user to room.
 
-        url = "/_synapse/admin/v1/join/{}".format(private_room_id)
+        url = f"/_synapse/admin/v1/join/{private_room_id}"
         body = json.dumps({"user_id": self.second_user_id})
 
         channel = self.make_request(
@@ -1493,7 +1493,7 @@ def test_join_private_room_if_owner(self):
         private_room_id = self.helper.create_room_as(
             self.admin_user, tok=self.admin_user_tok, is_public=False
         )
-        url = "/_synapse/admin/v1/join/{}".format(private_room_id)
+        url = f"/_synapse/admin/v1/join/{private_room_id}"
         body = json.dumps({"user_id": self.second_user_id})
 
         channel = self.make_request(
@@ -1633,7 +1633,7 @@ def test_public_room(self):
 
         channel = self.make_request(
             "POST",
-            "/_synapse/admin/v1/rooms/{}/make_room_admin".format(room_id),
+            f"/_synapse/admin/v1/rooms/{room_id}/make_room_admin",
             content={},
             access_token=self.admin_user_tok,
         )
@@ -1660,7 +1660,7 @@ def test_private_room(self):
 
         channel = self.make_request(
             "POST",
-            "/_synapse/admin/v1/rooms/{}/make_room_admin".format(room_id),
+            f"/_synapse/admin/v1/rooms/{room_id}/make_room_admin",
             content={},
             access_token=self.admin_user_tok,
         )
@@ -1686,7 +1686,7 @@ def test_other_user(self):
 
         channel = self.make_request(
             "POST",
-            "/_synapse/admin/v1/rooms/{}/make_room_admin".format(room_id),
+            f"/_synapse/admin/v1/rooms/{room_id}/make_room_admin",
             content={"user_id": self.second_user_id},
             access_token=self.admin_user_tok,
         )
@@ -1720,7 +1720,7 @@ def test_not_enough_power(self):
 
         channel = self.make_request(
             "POST",
-            "/_synapse/admin/v1/rooms/{}/make_room_admin".format(room_id),
+            f"/_synapse/admin/v1/rooms/{room_id}/make_room_admin",
             content={},
             access_token=self.admin_user_tok,
         )
diff --git a/tests/rest/client/v1/test_rooms.py b/tests/rest/client/v1/test_rooms.py
index e94566ffd70b..3df070c93653 100644
--- a/tests/rest/client/v1/test_rooms.py
+++ b/tests/rest/client/v1/test_rooms.py
@@ -1206,7 +1206,7 @@ def test_join_reason(self):
         reason = "hello"
         channel = self.make_request(
             "POST",
-            "/_matrix/client/r0/rooms/{}/join".format(self.room_id),
+            f"/_matrix/client/r0/rooms/{self.room_id}/join",
             content={"reason": reason},
             access_token=self.second_tok,
         )
@@ -1220,7 +1220,7 @@ def test_leave_reason(self):
         reason = "hello"
         channel = self.make_request(
             "POST",
-            "/_matrix/client/r0/rooms/{}/leave".format(self.room_id),
+            f"/_matrix/client/r0/rooms/{self.room_id}/leave",
             content={"reason": reason},
             access_token=self.second_tok,
         )
@@ -1234,7 +1234,7 @@ def test_kick_reason(self):
         reason = "hello"
         channel = self.make_request(
             "POST",
-            "/_matrix/client/r0/rooms/{}/kick".format(self.room_id),
+            f"/_matrix/client/r0/rooms/{self.room_id}/kick",
             content={"reason": reason, "user_id": self.second_user_id},
             access_token=self.second_tok,
         )
@@ -1248,7 +1248,7 @@ def test_ban_reason(self):
         reason = "hello"
         channel = self.make_request(
             "POST",
-            "/_matrix/client/r0/rooms/{}/ban".format(self.room_id),
+            f"/_matrix/client/r0/rooms/{self.room_id}/ban",
             content={"reason": reason, "user_id": self.second_user_id},
             access_token=self.creator_tok,
         )
@@ -1260,7 +1260,7 @@ def test_unban_reason(self):
         reason = "hello"
         channel = self.make_request(
             "POST",
-            "/_matrix/client/r0/rooms/{}/unban".format(self.room_id),
+            f"/_matrix/client/r0/rooms/{self.room_id}/unban",
             content={"reason": reason, "user_id": self.second_user_id},
             access_token=self.creator_tok,
         )
@@ -1272,7 +1272,7 @@ def test_invite_reason(self):
         reason = "hello"
         channel = self.make_request(
             "POST",
-            "/_matrix/client/r0/rooms/{}/invite".format(self.room_id),
+            f"/_matrix/client/r0/rooms/{self.room_id}/invite",
             content={"reason": reason, "user_id": self.second_user_id},
             access_token=self.creator_tok,
         )
@@ -1291,7 +1291,7 @@ def test_reject_invite_reason(self):
         reason = "hello"
         channel = self.make_request(
             "POST",
-            "/_matrix/client/r0/rooms/{}/leave".format(self.room_id),
+            f"/_matrix/client/r0/rooms/{self.room_id}/leave",
             content={"reason": reason},
             access_token=self.second_tok,
         )
diff --git a/tests/rest/client/v2_alpha/test_relations.py b/tests/rest/client/v2_alpha/test_relations.py
index 856aa8682f7e..2e2f94742ef8 100644
--- a/tests/rest/client/v2_alpha/test_relations.py
+++ b/tests/rest/client/v2_alpha/test_relations.py
@@ -273,7 +273,7 @@ def test_aggregation_pagination_within_group(self):
 
         prev_token = None
         found_event_ids = []
-        encoded_key = urllib.parse.quote_plus("👍".encode("utf-8"))
+        encoded_key = urllib.parse.quote_plus("👍".encode())
         for _ in range(20):
             from_token = ""
             if prev_token:
diff --git a/tests/rest/client/v2_alpha/test_report_event.py b/tests/rest/client/v2_alpha/test_report_event.py
index 1ec6b05e5bd2..a76a6fef1e3f 100644
--- a/tests/rest/client/v2_alpha/test_report_event.py
+++ b/tests/rest/client/v2_alpha/test_report_event.py
@@ -41,7 +41,7 @@ def prepare(self, reactor, clock, hs):
         self.helper.join(self.room_id, user=self.admin_user, tok=self.admin_user_tok)
         resp = self.helper.send(self.room_id, tok=self.admin_user_tok)
         self.event_id = resp["event_id"]
-        self.report_path = "rooms/{}/report/{}".format(self.room_id, self.event_id)
+        self.report_path = f"rooms/{self.room_id}/report/{self.event_id}"
 
     def test_reason_str_and_score_int(self):
         data = {"reason": "this makes me sad", "score": -100}
diff --git a/tests/rest/media/v1/test_media_storage.py b/tests/rest/media/v1/test_media_storage.py
index 95e707584160..2d6b49692ee7 100644
--- a/tests/rest/media/v1/test_media_storage.py
+++ b/tests/rest/media/v1/test_media_storage.py
@@ -310,7 +310,7 @@ def test_disposition_filenamestar_utf8escaped(self):
         correctly decode it as the UTF-8 string, and use filename* in the
         response.
         """
-        filename = parse.quote("\u2603".encode("utf8")).encode("ascii")
+        filename = parse.quote("\u2603".encode()).encode("ascii")
         channel = self._req(
             b"inline; filename*=utf-8''" + filename + self.test_image.extension
         )
diff --git a/tests/storage/test_directory.py b/tests/storage/test_directory.py
index 41bef62ca8fc..43628ce44f41 100644
--- a/tests/storage/test_directory.py
+++ b/tests/storage/test_directory.py
@@ -59,5 +59,5 @@ def test_delete_alias(self):
         self.assertEqual(self.room.to_string(), room_id)
 
         self.assertIsNone(
-            (self.get_success(self.store.get_association_from_room_alias(self.alias)))
+            self.get_success(self.store.get_association_from_room_alias(self.alias))
         )
diff --git a/tests/storage/test_profile.py b/tests/storage/test_profile.py
index 8a446da848d7..a1ba99ff140e 100644
--- a/tests/storage/test_profile.py
+++ b/tests/storage/test_profile.py
@@ -45,11 +45,7 @@ def test_displayname(self):
         )
 
         self.assertIsNone(
-            (
-                self.get_success(
-                    self.store.get_profile_displayname(self.u_frank.localpart)
-                )
-            )
+            self.get_success(self.store.get_profile_displayname(self.u_frank.localpart))
         )
 
     def test_avatar_url(self):
@@ -76,9 +72,5 @@ def test_avatar_url(self):
         )
 
         self.assertIsNone(
-            (
-                self.get_success(
-                    self.store.get_profile_avatar_url(self.u_frank.localpart)
-                )
-            )
+            self.get_success(self.store.get_profile_avatar_url(self.u_frank.localpart))
         )
diff --git a/tests/storage/test_purge.py b/tests/storage/test_purge.py
index 54c5b470c789..e5574063f17f 100644
--- a/tests/storage/test_purge.py
+++ b/tests/storage/test_purge.py
@@ -75,7 +75,7 @@ def test_purge_history_wont_delete_extrems(self):
         token = self.get_success(
             self.store.get_topological_token_for_event(last["event_id"])
         )
-        event = "t{}-{}".format(token.topological + 1, token.stream + 1)
+        event = f"t{token.topological + 1}-{token.stream + 1}"
 
         # Purge everything before this topological token
         f = self.get_failure(
diff --git a/tests/storage/test_room.py b/tests/storage/test_room.py
index 70257bf21027..31ce7f62528f 100644
--- a/tests/storage/test_room.py
+++ b/tests/storage/test_room.py
@@ -49,7 +49,7 @@ def test_get_room(self):
         )
 
     def test_get_room_unknown_room(self):
-        self.assertIsNone((self.get_success(self.store.get_room("!uknown:test"))))
+        self.assertIsNone(self.get_success(self.store.get_room("!uknown:test")))
 
     def test_get_room_with_stats(self):
         self.assertDictContainsSubset(
diff --git a/tests/test_types.py b/tests/test_types.py
index d7881021d3f5..0d0c00d97a06 100644
--- a/tests/test_types.py
+++ b/tests/test_types.py
@@ -103,6 +103,4 @@ def testLeadingUnderscore(self):
     def testNonAscii(self):
         # this should work with either a unicode or a bytes
         self.assertEqual(map_username_to_mxid_localpart("têst"), "t=c3=aast")
-        self.assertEqual(
-            map_username_to_mxid_localpart("têst".encode("utf-8")), "t=c3=aast"
-        )
+        self.assertEqual(map_username_to_mxid_localpart("têst".encode()), "t=c3=aast")
diff --git a/tests/unittest.py b/tests/unittest.py
index 74db7c08f1ee..907b94b10a99 100644
--- a/tests/unittest.py
+++ b/tests/unittest.py
@@ -140,7 +140,7 @@ def assertObjectHasAttributes(self, attrs, obj):
             try:
                 self.assertEquals(attrs[key], getattr(obj, key))
             except AssertionError as e:
-                raise (type(e))("Assert error for '.{}':".format(key)) from e
+                raise (type(e))(f"Assert error for '.{key}':") from e
 
     def assert_dict(self, required, actual):
         """Does a partial assert of a dict.