synapse/tests/test_utils/__init__.py

# -*- coding: utf-8 -*-
# Copyright 2019 New Vector Ltd
# Copyright 2020 The Matrix.org Foundation C.I.C
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""
Utilities for running the unit tests
"""
from asyncio import Future
from typing import Any, Awaitable, TypeVar

TV = TypeVar("TV")


def get_awaitable_result(awaitable: Awaitable[TV]) -> TV:
    """Get the result from an Awaitable which should have completed

    Asserts that the given awaitable has a result ready, and returns its value
    """
    i = awaitable.__await__()
    try:
        next(i)
    except StopIteration as e:
        # awaitable returned a result
        return e.value

    # if next didn't raise, the awaitable hasn't completed.
    raise Exception("awaitable has not yet completed")


def make_awaitable(result: Any) -> Awaitable[Any]:
    """
    Makes an awaitable, suitable for mocking an `async` function.
    This uses Futures as they can be awaited multiple times so can be returned
    to multiple callers.
    """
    future = Future()  # type: ignore
    future.set_result(result)
    return future