为`mock.patch`做一个包装 [英] Making a wrapper for `mock.patch`

问题描述

mock.patch中的一些自定义补丁程序，我想一遍又一遍地使用，而不会在补丁程序设置的复制粘贴中乱丢我的测试代码.例如 datetime.date 的这一非常方便的补丁，该补丁适用于日期时间，将用我的代码填充

Some customized patches from mock.patch I want to use over and over without littering my test code with copy-pastes of the patch setup. e.g. this very handy patch of datetime.date, which, adapted for datetime, would fill my code with

with patch('mymodule.datetime') as mock_datetime:
    mock_datetime.datetime.utcnow.return_value = datetime.datetime(2010, 10, 8, 9, 10)
    mock_date.datetime.side_effect = lambda *args, **kw: datetime.datetime(*args, **kw)

如何将此功能包装到单线呼叫中?

How can I wrap this functionality into a one-line call?

推荐答案

这里是一个资源管理器类，它将为您完成此任务.由于您可能希望将其放在与测试类不同的文件中，因此它使用inspect查找调用模块，以便可以将正确限定的目标模块名称传递给mock.patch.

Here's a resource manager class that will do that for you. Since you might want to put it in a separate file from your test classes, it uses inspect to look up the calling module, so that it can pass the correctly qualified target module name to mock.patch.

import datetime
import inspect
# import mock according to your python version

class mock_datetime(object):

    def __init__(self, target, new_utcnow):
        self.new_utcnow = new_utcnow
        self.target = target

    def __enter__(self):
        calling_module = inspect.getmodule(inspect.stack()[1][0])
        target_from_here = calling_module.__name__ + '.' + self.target
        self.patcher = mock.patch(target_from_here)
        mock_dt = self.patcher.start()
        mock_dt.datetime.utcnow.return_value = self.new_utcnow.replace(tzinfo=None)
        mock_dt.datetime.side_effect = lambda *args, **kw: datetime.datetime(*args, **kw)
        return mock_dt

    def __exit__(self, *args, **kwargs):
        self.patcher.stop()

然后您可以使用

with mock_datetime('mymodule.datetime', datetime.datetime(2016, 3, 23)):
    assert mymodule.datetime.datetime.utcnow() == datetime.datetime(2016, 3, 23)

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