synapse-old/tests/unittest.py

936 lines
31 KiB
Python

# Copyright 2014-2016 OpenMarket Ltd
# Copyright 2018 New Vector
# Copyright 2019 Matrix.org Federation C.I.C
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import gc
import hashlib
import hmac
import logging
import secrets
import time
from typing import (
Any,
Awaitable,
Callable,
ClassVar,
Dict,
Generic,
Iterable,
List,
NoReturn,
Optional,
Tuple,
Type,
TypeVar,
Union,
)
from unittest.mock import Mock, patch
import canonicaljson
import signedjson.key
import unpaddedbase64
from typing_extensions import Concatenate, ParamSpec, Protocol
from twisted.internet.defer import Deferred, ensureDeferred
from twisted.python.failure import Failure
from twisted.python.threadpool import ThreadPool
from twisted.test.proto_helpers import MemoryReactor
from twisted.trial import unittest
from twisted.web.resource import Resource
from twisted.web.server import Request
from synapse import events
from synapse.api.constants import EventTypes
from synapse.api.room_versions import KNOWN_ROOM_VERSIONS, RoomVersion
from synapse.config.homeserver import HomeServerConfig
from synapse.config.server import DEFAULT_ROOM_VERSION
from synapse.crypto.event_signing import add_hashes_and_signatures
from synapse.federation.transport.server import TransportLayerServer
from synapse.http.server import JsonResource
from synapse.http.site import SynapseRequest, SynapseSite
from synapse.logging.context import (
SENTINEL_CONTEXT,
LoggingContext,
current_context,
set_current_context,
)
from synapse.rest import RegisterServletsFunc
from synapse.server import HomeServer
from synapse.storage.keys import FetchKeyResult
from synapse.types import JsonDict, Requester, UserID, create_requester
from synapse.util import Clock
from synapse.util.httpresourcetree import create_resource_tree
from tests.server import (
CustomHeaderType,
FakeChannel,
get_clock,
make_request,
setup_test_homeserver,
)
from tests.test_utils import event_injection, setup_awaitable_errors
from tests.test_utils.logging_setup import setup_logging
from tests.utils import default_config, setupdb
setupdb()
setup_logging()
TV = TypeVar("TV")
_ExcType = TypeVar("_ExcType", bound=BaseException, covariant=True)
P = ParamSpec("P")
R = TypeVar("R")
S = TypeVar("S")
class _TypedFailure(Generic[_ExcType], Protocol):
"""Extension to twisted.Failure, where the 'value' has a certain type."""
@property
def value(self) -> _ExcType:
...
def around(target: TV) -> Callable[[Callable[Concatenate[S, P], R]], None]:
"""A CLOS-style 'around' modifier, which wraps the original method of the
given instance with another piece of code.
@around(self)
def method_name(orig, *args, **kwargs):
return orig(*args, **kwargs)
"""
def _around(code: Callable[Concatenate[S, P], R]) -> None:
name = code.__name__
orig = getattr(target, name)
def new(*args: P.args, **kwargs: P.kwargs) -> R:
return code(orig, *args, **kwargs)
setattr(target, name, new)
return _around
class TestCase(unittest.TestCase):
"""A subclass of twisted.trial's TestCase which looks for 'loglevel'
attributes on both itself and its individual test methods, to override the
root logger's logging level while that test (case|method) runs."""
def __init__(self, methodName: str):
super().__init__(methodName)
method = getattr(self, methodName)
level = getattr(method, "loglevel", getattr(self, "loglevel", None))
@around(self)
def setUp(orig: Callable[[], R]) -> R:
# if we're not starting in the sentinel logcontext, then to be honest
# all future bets are off.
if current_context():
self.fail(
"Test starting with non-sentinel logging context %s"
% (current_context(),)
)
old_level = logging.getLogger().level
if level is not None and old_level != level:
@around(self)
def tearDown(orig: Callable[[], R]) -> R:
ret = orig()
logging.getLogger().setLevel(old_level)
return ret
logging.getLogger().setLevel(level)
# Trial messes with the warnings configuration, thus this has to be
# done in the context of an individual TestCase.
self.addCleanup(setup_awaitable_errors())
return orig()
@around(self)
def tearDown(orig: Callable[[], R]) -> R:
ret = orig()
# force a GC to workaround problems with deferreds leaking logcontexts when
# they are GCed (see the logcontext docs)
gc.collect()
set_current_context(SENTINEL_CONTEXT)
return ret
def assertObjectHasAttributes(self, attrs: Dict[str, object], obj: object) -> None:
"""Asserts that the given object has each of the attributes given, and
that the value of each matches according to assertEqual."""
for key in attrs.keys():
if not hasattr(obj, key):
raise AssertionError("Expected obj to have a '.%s'" % key)
try:
self.assertEqual(attrs[key], getattr(obj, key))
except AssertionError as e:
raise (type(e))(f"Assert error for '.{key}':") from e
def assert_dict(self, required: dict, actual: dict) -> None:
"""Does a partial assert of a dict.
Args:
required: The keys and value which MUST be in 'actual'.
actual: The test result. Extra keys will not be checked.
"""
for key in required:
self.assertEqual(
required[key], actual[key], msg="%s mismatch. %s" % (key, actual)
)
def DEBUG(target: TV) -> TV:
"""A decorator to set the .loglevel attribute to logging.DEBUG.
Can apply to either a TestCase or an individual test method."""
target.loglevel = logging.DEBUG # type: ignore[attr-defined]
return target
def INFO(target: TV) -> TV:
"""A decorator to set the .loglevel attribute to logging.INFO.
Can apply to either a TestCase or an individual test method."""
target.loglevel = logging.INFO # type: ignore[attr-defined]
return target
def logcontext_clean(target: TV) -> TV:
"""A decorator which marks the TestCase or method as 'logcontext_clean'
... ie, any logcontext errors should cause a test failure
"""
def logcontext_error(msg: str) -> NoReturn:
raise AssertionError("logcontext error: %s" % (msg))
patcher = patch("synapse.logging.context.logcontext_error", new=logcontext_error)
return patcher(target) # type: ignore[call-overload]
class HomeserverTestCase(TestCase):
"""
A base TestCase that reduces boilerplate for HomeServer-using test cases.
Defines a setUp method which creates a mock reactor, and instantiates a homeserver
running on that reactor.
There are various hooks for modifying the way that the homeserver is instantiated:
* override make_homeserver, for example by making it pass different parameters into
setup_test_homeserver.
* override default_config, to return a modified configuration dictionary for use
by setup_test_homeserver.
* On a per-test basis, you can use the @override_config decorator to give a
dictionary containing additional configuration settings to be added to the basic
config dict.
Attributes:
servlets: List of servlet registration function.
user_id (str): The user ID to assume if auth is hijacked.
hijack_auth: Whether to hijack auth to return the user specified
in user_id.
"""
hijack_auth: ClassVar[bool] = True
needs_threadpool: ClassVar[bool] = False
servlets: ClassVar[List[RegisterServletsFunc]] = []
def __init__(self, methodName: str):
super().__init__(methodName)
# see if we have any additional config for this test
method = getattr(self, methodName)
self._extra_config = getattr(method, "_extra_config", None)
def setUp(self) -> None:
"""
Set up the TestCase by calling the homeserver constructor, optionally
hijacking the authentication system to return a fixed user, and then
calling the prepare function.
"""
self.reactor, self.clock = get_clock()
self._hs_args = {"clock": self.clock, "reactor": self.reactor}
self.hs = self.make_homeserver(self.reactor, self.clock)
# Honour the `use_frozen_dicts` config option. We have to do this
# manually because this is taken care of in the app `start` code, which
# we don't run. Plus we want to reset it on tearDown.
events.USE_FROZEN_DICTS = self.hs.config.server.use_frozen_dicts
if self.hs is None:
raise Exception("No homeserver returned from make_homeserver.")
if not isinstance(self.hs, HomeServer):
raise Exception("A homeserver wasn't returned, but %r" % (self.hs,))
# create the root resource, and a site to wrap it.
self.resource = self.create_test_resource()
self.site = SynapseSite(
logger_name="synapse.access.http.fake",
site_tag=self.hs.config.server.server_name,
config=self.hs.config.server.listeners[0],
resource=self.resource,
server_version_string="1",
max_request_body_size=4096,
reactor=self.reactor,
)
from tests.rest.client.utils import RestHelper
self.helper = RestHelper(self.hs, self.site, getattr(self, "user_id", None))
if hasattr(self, "user_id"):
if self.hijack_auth:
assert self.helper.auth_user_id is not None
token = "some_fake_token"
# We need a valid token ID to satisfy foreign key constraints.
token_id = self.get_success(
self.hs.get_datastores().main.add_access_token_to_user(
self.helper.auth_user_id,
token,
None,
None,
)
)
# This has to be a function and not just a Mock, because
# `self.helper.auth_user_id` is temporarily reassigned in some tests
async def get_requester(*args, **kwargs) -> Requester:
assert self.helper.auth_user_id is not None
return create_requester(
user_id=UserID.from_string(self.helper.auth_user_id),
access_token_id=token_id,
)
# Type ignore: mypy doesn't like us assigning to methods.
self.hs.get_auth().get_user_by_req = get_requester # type: ignore[assignment]
self.hs.get_auth().get_user_by_access_token = get_requester # type: ignore[assignment]
self.hs.get_auth().get_access_token_from_request = Mock(return_value=token) # type: ignore[assignment]
if self.needs_threadpool:
self.reactor.threadpool = ThreadPool() # type: ignore[assignment]
self.addCleanup(self.reactor.threadpool.stop)
self.reactor.threadpool.start()
if hasattr(self, "prepare"):
self.prepare(self.reactor, self.clock, self.hs)
def tearDown(self) -> None:
# Reset to not use frozen dicts.
events.USE_FROZEN_DICTS = False
def wait_on_thread(self, deferred: Deferred, timeout: int = 10) -> None:
"""
Wait until a Deferred is done, where it's waiting on a real thread.
"""
start_time = time.time()
while not deferred.called:
if start_time + timeout < time.time():
raise ValueError("Timed out waiting for threadpool")
self.reactor.advance(0.01)
time.sleep(0.01)
def wait_for_background_updates(self) -> None:
"""Block until all background database updates have completed."""
store = self.hs.get_datastores().main
while not self.get_success(
store.db_pool.updates.has_completed_background_updates()
):
self.get_success(
store.db_pool.updates.do_next_background_update(False), by=0.1
)
def make_homeserver(self, reactor: MemoryReactor, clock: Clock):
"""
Make and return a homeserver.
Args:
reactor: A Twisted Reactor, or something that pretends to be one.
clock: The Clock, associated with the reactor.
Returns:
A homeserver suitable for testing.
Function to be overridden in subclasses.
"""
hs = self.setup_test_homeserver()
return hs
def create_test_resource(self) -> Resource:
"""
Create a the root resource for the test server.
The default calls `self.create_resource_dict` and builds the resultant dict
into a tree.
"""
root_resource = Resource()
create_resource_tree(self.create_resource_dict(), root_resource)
return root_resource
def create_resource_dict(self) -> Dict[str, Resource]:
"""Create a resource tree for the test server
A resource tree is a mapping from path to twisted.web.resource.
The default implementation creates a JsonResource and calls each function in
`servlets` to register servlets against it.
"""
servlet_resource = JsonResource(self.hs)
for servlet in self.servlets:
servlet(self.hs, servlet_resource)
return {
"/_matrix/client": servlet_resource,
"/_synapse/admin": servlet_resource,
}
def default_config(self) -> JsonDict:
"""
Get a default HomeServer config dict.
"""
config = default_config("test")
# apply any additional config which was specified via the override_config
# decorator.
if self._extra_config is not None:
config.update(self._extra_config)
return config
def prepare(
self, reactor: MemoryReactor, clock: Clock, homeserver: HomeServer
) -> None:
"""
Prepare for the test. This involves things like mocking out parts of
the homeserver, or building test data common across the whole test
suite.
Args:
reactor: A Twisted Reactor, or something that pretends to be one.
clock: The Clock, associated with the reactor.
homeserver: The HomeServer to test against.
Function to optionally be overridden in subclasses.
"""
def make_request(
self,
method: Union[bytes, str],
path: Union[bytes, str],
content: Union[bytes, str, JsonDict] = b"",
access_token: Optional[str] = None,
request: Type[Request] = SynapseRequest,
shorthand: bool = True,
federation_auth_origin: Optional[bytes] = None,
content_is_form: bool = False,
await_result: bool = True,
custom_headers: Optional[Iterable[CustomHeaderType]] = None,
client_ip: str = "127.0.0.1",
) -> FakeChannel:
"""
Create a SynapseRequest at the path using the method and containing the
given content.
Args:
method: The HTTP request method ("verb").
path: The HTTP path, suitably URL encoded (e.g. escaped UTF-8 & spaces
and such). content (bytes or dict): The body of the request.
JSON-encoded, if a dict.
shorthand: Whether to try and be helpful and prefix the given URL
with the usual REST API path, if it doesn't contain it.
federation_auth_origin: if set to not-None, we will add a fake
Authorization header pretenting to be the given server name.
content_is_form: Whether the content is URL encoded form data. Adds the
'Content-Type': 'application/x-www-form-urlencoded' header.
await_result: whether to wait for the request to complete rendering. If
true (the default), will pump the test reactor until the the renderer
tells the channel the request is finished.
custom_headers: (name, value) pairs to add as request headers
client_ip: The IP to use as the requesting IP. Useful for testing
ratelimiting.
Returns:
The FakeChannel object which stores the result of the request.
"""
return make_request(
self.reactor,
self.site,
method,
path,
content,
access_token,
request,
shorthand,
federation_auth_origin,
content_is_form,
await_result,
custom_headers,
client_ip,
)
def setup_test_homeserver(self, *args: Any, **kwargs: Any) -> HomeServer:
"""
Set up the test homeserver, meant to be called by the overridable
make_homeserver. It automatically passes through the test class's
clock & reactor.
Args:
See tests.utils.setup_test_homeserver.
Returns:
synapse.server.HomeServer
"""
kwargs = dict(kwargs)
kwargs.update(self._hs_args)
if "config" not in kwargs:
config = self.default_config()
else:
config = kwargs["config"]
# Parse the config from a config dict into a HomeServerConfig
config_obj = HomeServerConfig()
config_obj.parse_config_dict(config, "", "")
kwargs["config"] = config_obj
async def run_bg_updates() -> None:
with LoggingContext("run_bg_updates"):
self.get_success(stor.db_pool.updates.run_background_updates(False))
hs = setup_test_homeserver(self.addCleanup, *args, **kwargs)
stor = hs.get_datastores().main
# Run the database background updates, when running against "master".
if hs.__class__.__name__ == "TestHomeServer":
self.get_success(run_bg_updates())
return hs
def pump(self, by: float = 0.0) -> None:
"""
Pump the reactor enough that Deferreds will fire.
"""
self.reactor.pump([by] * 100)
def get_success(self, d: Awaitable[TV], by: float = 0.0) -> TV:
deferred: Deferred[TV] = ensureDeferred(d) # type: ignore[arg-type]
self.pump(by=by)
return self.successResultOf(deferred)
def get_failure(
self, d: Awaitable[Any], exc: Type[_ExcType]
) -> _TypedFailure[_ExcType]:
"""
Run a Deferred and get a Failure from it. The failure must be of the type `exc`.
"""
deferred: Deferred[Any] = ensureDeferred(d) # type: ignore[arg-type]
self.pump()
return self.failureResultOf(deferred, exc)
def get_success_or_raise(self, d: Awaitable[TV], by: float = 0.0) -> TV:
"""Drive deferred to completion and return result or raise exception
on failure.
"""
deferred: Deferred[TV] = ensureDeferred(d) # type: ignore[arg-type]
results: list = []
deferred.addBoth(results.append)
self.pump(by=by)
if not results:
self.fail(
"Success result expected on {!r}, found no result instead".format(
deferred
)
)
result = results[0]
if isinstance(result, Failure):
result.raiseException()
return result
def register_user(
self,
username: str,
password: str,
admin: Optional[bool] = False,
displayname: Optional[str] = None,
) -> str:
"""
Register a user. Requires the Admin API be registered.
Args:
username: The user part of the new user.
password: The password of the new user.
admin: Whether the user should be created as an admin or not.
displayname: The displayname of the new user.
Returns:
The MXID of the new user.
"""
self.hs.config.registration.registration_shared_secret = "shared"
# Create the user
channel = self.make_request("GET", "/_synapse/admin/v1/register")
self.assertEqual(channel.code, 200, msg=channel.result)
nonce = channel.json_body["nonce"]
want_mac = hmac.new(key=b"shared", digestmod=hashlib.sha1)
nonce_str = b"\x00".join([username.encode("utf8"), password.encode("utf8")])
if admin:
nonce_str += b"\x00admin"
else:
nonce_str += b"\x00notadmin"
want_mac.update(nonce.encode("ascii") + b"\x00" + nonce_str)
want_mac_digest = want_mac.hexdigest()
body = {
"nonce": nonce,
"username": username,
"displayname": displayname,
"password": password,
"admin": admin,
"mac": want_mac_digest,
"inhibit_login": True,
}
channel = self.make_request("POST", "/_synapse/admin/v1/register", body)
self.assertEqual(channel.code, 200, channel.json_body)
user_id = channel.json_body["user_id"]
return user_id
def register_appservice_user(
self,
username: str,
appservice_token: str,
) -> Tuple[str, str]:
"""Register an appservice user as an application service.
Requires the client-facing registration API be registered.
Args:
username: the user to be registered by an application service.
Should NOT be a full username, i.e. just "localpart" as opposed to "@localpart:hostname"
appservice_token: the acccess token for that application service.
Raises: if the request to '/register' does not return 200 OK.
Returns:
The MXID of the new user, the device ID of the new user's first device.
"""
channel = self.make_request(
"POST",
"/_matrix/client/r0/register",
{
"username": username,
"type": "m.login.application_service",
},
access_token=appservice_token,
)
self.assertEqual(channel.code, 200, channel.json_body)
return channel.json_body["user_id"], channel.json_body["device_id"]
def login(
self,
username: str,
password: str,
device_id: Optional[str] = None,
additional_request_fields: Optional[Dict[str, str]] = None,
custom_headers: Optional[Iterable[CustomHeaderType]] = None,
) -> str:
"""
Log in a user, and get an access token. Requires the Login API be registered.
Args:
username: The localpart to assign to the new user.
password: The password to assign to the new user.
device_id: An optional device ID to assign to the new device created during
login.
additional_request_fields: A dictionary containing any additional /login
request fields and their values.
custom_headers: Custom HTTP headers and values to add to the /login request.
Returns:
The newly registered user's Matrix ID.
"""
body = {"type": "m.login.password", "user": username, "password": password}
if device_id:
body["device_id"] = device_id
if additional_request_fields:
body.update(additional_request_fields)
channel = self.make_request(
"POST",
"/_matrix/client/r0/login",
body,
custom_headers=custom_headers,
)
self.assertEqual(channel.code, 200, channel.result)
access_token = channel.json_body["access_token"]
return access_token
def create_and_send_event(
self,
room_id: str,
user: UserID,
soft_failed: bool = False,
prev_event_ids: Optional[List[str]] = None,
) -> str:
"""
Create and send an event.
Args:
soft_failed: Whether to create a soft failed event or not
prev_event_ids: Explicitly set the prev events,
or if None just use the default
Returns:
The new event's ID.
"""
event_creator = self.hs.get_event_creation_handler()
requester = create_requester(user)
event, context = self.get_success(
event_creator.create_event(
requester,
{
"type": EventTypes.Message,
"room_id": room_id,
"sender": user.to_string(),
"content": {"body": secrets.token_hex(), "msgtype": "m.text"},
},
prev_event_ids=prev_event_ids,
)
)
if soft_failed:
event.internal_metadata.soft_failed = True
self.get_success(
event_creator.handle_new_client_event(
requester, events_and_context=[(event, context)]
)
)
return event.event_id
def inject_room_member(self, room: str, user: str, membership: str) -> None:
"""
Inject a membership event into a room.
Deprecated: use event_injection.inject_room_member directly
Args:
room: Room ID to inject the event into.
user: MXID of the user to inject the membership for.
membership: The membership type.
"""
self.get_success(
event_injection.inject_member_event(self.hs, room, user, membership)
)
class FederatingHomeserverTestCase(HomeserverTestCase):
"""
A federating homeserver, set up to validate incoming federation requests
"""
OTHER_SERVER_NAME = "other.example.com"
OTHER_SERVER_SIGNATURE_KEY = signedjson.key.generate_signing_key("test")
def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
super().prepare(reactor, clock, hs)
# poke the other server's signing key into the key store, so that we don't
# make requests for it
verify_key = signedjson.key.get_verify_key(self.OTHER_SERVER_SIGNATURE_KEY)
verify_key_id = "%s:%s" % (verify_key.alg, verify_key.version)
self.get_success(
hs.get_datastores().main.store_server_verify_keys(
from_server=self.OTHER_SERVER_NAME,
ts_added_ms=clock.time_msec(),
verify_keys=[
(
self.OTHER_SERVER_NAME,
verify_key_id,
FetchKeyResult(
verify_key=verify_key,
valid_until_ts=clock.time_msec() + 10000,
),
)
],
)
)
def create_resource_dict(self) -> Dict[str, Resource]:
d = super().create_resource_dict()
d["/_matrix/federation"] = TransportLayerServer(self.hs)
return d
def make_signed_federation_request(
self,
method: str,
path: str,
content: Optional[JsonDict] = None,
await_result: bool = True,
custom_headers: Optional[Iterable[CustomHeaderType]] = None,
client_ip: str = "127.0.0.1",
) -> FakeChannel:
"""Make an inbound signed federation request to this server
The request is signed as if it came from "other.example.com", which our HS
already has the keys for.
"""
if custom_headers is None:
custom_headers = []
else:
custom_headers = list(custom_headers)
custom_headers.append(
(
"Authorization",
_auth_header_for_request(
origin=self.OTHER_SERVER_NAME,
destination=self.hs.hostname,
signing_key=self.OTHER_SERVER_SIGNATURE_KEY,
method=method,
path=path,
content=content,
),
)
)
return make_request(
self.reactor,
self.site,
method=method,
path=path,
content=content if content is not None else "",
shorthand=False,
await_result=await_result,
custom_headers=custom_headers,
client_ip=client_ip,
)
def add_hashes_and_signatures_from_other_server(
self,
event_dict: JsonDict,
room_version: RoomVersion = KNOWN_ROOM_VERSIONS[DEFAULT_ROOM_VERSION],
) -> JsonDict:
"""Adds hashes and signatures to the given event dict
Returns:
The modified event dict, for convenience
"""
add_hashes_and_signatures(
room_version,
event_dict,
signature_name=self.OTHER_SERVER_NAME,
signing_key=self.OTHER_SERVER_SIGNATURE_KEY,
)
return event_dict
def _auth_header_for_request(
origin: str,
destination: str,
signing_key: signedjson.key.SigningKey,
method: str,
path: str,
content: Optional[JsonDict],
) -> str:
"""Build a suitable Authorization header for an outgoing federation request"""
request_description: JsonDict = {
"method": method,
"uri": path,
"destination": destination,
"origin": origin,
}
if content is not None:
request_description["content"] = content
signature_base64 = unpaddedbase64.encode_base64(
signing_key.sign(
canonicaljson.encode_canonical_json(request_description)
).signature
)
return (
f"X-Matrix origin={origin},"
f"key={signing_key.alg}:{signing_key.version},"
f"sig={signature_base64}"
)
def override_config(extra_config: JsonDict) -> Callable[[TV], TV]:
"""A decorator which can be applied to test functions to give additional HS config
For use
For example:
class MyTestCase(HomeserverTestCase):
@override_config({"enable_registration": False, ...})
def test_foo(self):
...
Args:
extra_config: Additional config settings to be merged into the default
config dict before instantiating the test homeserver.
"""
def decorator(func: TV) -> TV:
# This attribute is being defined.
func._extra_config = extra_config # type: ignore[attr-defined]
return func
return decorator
def skip_unless(condition: bool, reason: str) -> Callable[[TV], TV]:
"""A test decorator which will skip the decorated test unless a condition is set
For example:
class MyTestCase(TestCase):
@skip_unless(HAS_FOO, "Cannot test without foo")
def test_foo(self):
...
Args:
condition: If true, the test will be skipped
reason: the reason to give for skipping the test
"""
def decorator(f: TV) -> TV:
if not condition:
f.skip = reason # type: ignore
return f
return decorator