import asyncio
import time

from sleepfake import SleepFake

# Sync
with SleepFake():
    start = time.time()
    time.sleep(10)  # returns instantly
    assert time.time() - start >= 10


# Async: `async with` or plain `with` both work
async def main():
    async with SleepFake():
        start = asyncio.get_running_loop().time()
        await asyncio.sleep(5)  # returns instantly
        assert asyncio.get_running_loop().time() - start >= 5

Keep some modules on real clocks with ignore:

with SleepFake(ignore=["my_project.telemetry"]):
    ...

import asyncio
import time


def test_retry_logic(sleepfake):
    start = time.time()
    time.sleep(30)  # instantly skipped
    assert time.time() - start >= 30


async def test_polling(sleepfake):
    start = asyncio.get_running_loop().time()
    await asyncio.gather(asyncio.sleep(1), asyncio.sleep(5), asyncio.sleep(3))
    # All three complete instantly; the clock sits at +5 s
    assert asyncio.get_running_loop().time() - start >= 5

The fixture yields the active SleepFake; sleepfake.mock_sleep(60) advances the clock by hand.

Deprecated: asleepfake still works but warns. Use sleepfake for sync and async tests.

import time

import pytest


@pytest.mark.sleepfake
def test_marked():
    start = time.time()
    time.sleep(100)
    assert time.time() - start >= 100

Works on async tests, classes and modules (pytestmark) too.

Enable it in config or on the command line:

# pyproject.toml
[tool.pytest.ini_options]
sleepfake_autouse = true
sleepfake_ignore = ["my_project.telemetry", "my_project.metrics"]

pytest --sleepfake --sleepfake-ignore my_project.telemetry

Opt a single test out with @pytest.mark.no_sleepfake (it has no effect if the test explicitly requests the sleepfake fixture).

Directory-scoped ignores go in a conftest.py; the nearest one wins:

# conftest.py
pytest_sleepfake_ignore = ["my_project.telemetry"]

Function-scoped fixtures are set up and torn down with the fake active; session-, module- and class-scoped fixtures stay on real time.

asyncio.sleep always wakes instantly. Loop timers (asyncio.wait_for, asyncio.timeout, loop.call_later) fire once the event loop has been idle for autojump_threshold real seconds (default 0.02). That short grace period lets real I/O, such as a local test server, answer before a timeout is forced.

async def test_timeout(sleepfake):
    with pytest.raises(TimeoutError):
        async with asyncio.timeout(2):
            await asyncio.sleep(10)  # the clock stops at +2 s, like real asyncio

Tune it per instance or per project:

SleepFake(autojump_threshold=0)  # jump as soon as the loop is idle
SleepFake(autojump_threshold=math.inf)  # never jump: timers only fire when sleeps move the clock

[tool.pytest.ini_options]
sleepfake_autojump_threshold = "0.5"