如何在 Python 单元测试中存根 time.sleep()

Question

我想制作一个存根来防止 time.sleep(..) 休眠以提高单元测试的执行时间。

我拥有的是：

import time as orgtime

class time(orgtime):
    '''Stub for time.'''
    _sleep_speed_factor = 1.0

    @staticmethod
    def _set_sleep_speed_factor(sleep_speed_factor):
        '''Sets sleep speed.'''
        time._sleep_speed_factor = sleep_speed_factor


    @staticmethod
    def sleep(duration):
        '''Sleeps or not.'''
        print duration * time._sleep_speed_factor
        super.sleep(duration * time._sleep_speed_factor) 

但是，我在上面的第二个代码行（类定义）上收到以下错误：

TypeError: Error when calling the metaclass bases
module.__init__() takes at most 2 arguments (3 given).

如何修复错误？

Answer 1

您可以在测试中使用mock 库。

import time
from mock import patch

class MyTestCase(...):


     @patch('time.sleep', return_value=None)
     def my_test(self, patched_time_sleep):
          time.sleep(666)  # Should be instant

Answer 2

怎么样：

import time
from time import sleep as originalsleep

def newsleep(seconds):
    sleep_speed_factor = 10.0 
    originalsleep(seconds/sleep_speed_factor)

time.sleep = newsleep

这对我有用。我在测试开始时将其包括在内我想加快速度，最后我将原来的睡眠设置为以防万一。希望对你有帮助

Answer 3

使用freezegun 包可以帮助您做到这一点。

# fake.py
import functools
from datetime import datetime, timedelta
from unittest import mock

from freezegun import freeze_time


def fake_sleep(func):
    freezegun_control = None

    def fake_sleep(seconds):
        nonlocal freezegun_control
        utcnow = datetime.utcnow()
        if freezegun_control is not None:
            freezegun_control.stop()
        freezegun_control = freeze_time(utcnow + timedelta(seconds=seconds))
        freezegun_control.start()

    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        with mock.patch('time.sleep', fake_sleep):
            rv = func(*args, **kwargs)

            if freezegun_control is not None:
                freezegun_control.stop()
            return rv

    return wrapper


# test.py
from fake import fake_sleep

import time

@fake_sleep
def test_sleep():
    now = datetime.utcnow()

    for sleep_seconds in range(10):
        for i in range(1, 10):

            time.sleep(sleep_seconds)

            assert datetime.utcnow() - now >= timedelta(
                seconds=i * sleep_seconds)

1. 常见demo：请看freezegun README
2. pytest 演示：Gist fake sleep function fixture

Answer 4

接受的答案仍然有效。但是，unittest.mock 从 Python 3.3 开始就是 Python 标准库的官方部分。

import time
from unittest import TestCase
from unittest.mock import patch

class TestMyCase(TestCase):

    @patch('time.sleep', return_value=None)
    def test_my_method(self, patched_time_sleep):
        time.sleep(60)  # Should be instant

        # the mock should only be called once
        self.assertEqual(1, patched_time_sleep.call_count)
        # or 
        patched_time_sleep.assert_called_once()

    # alternative version using a context manager
    def test_my_method_alternative(self):
        with patch('time.sleep', return_value=None) as patched_time_sleep:
            time.sleep(60)  # Should be instant

        # the mock should only be called once
        self.assertEqual(1, patched_time_sleep.call_count)
        # or 
        patched_time_sleep.assert_called_once()

Answer 5

我正在使用pytest 并有以下固定装置到猴子补丁time.sleep：

import pytest


@pytest.fixture
def sleepless(monkeypatch):

    def sleep(seconds):
        pass

    monkeypatch.setattr(time, 'sleep', sleep)

然后在我需要“加速”睡眠的测试中，我只使用这个夹具：

import time

def test_sleep(sleepless):
    time.sleep(60)

因此，当您运行此测试时，您会看到它在更短的时间内完成：

= 1 passed in 0.02 seconds =