问Python中的模拟嵌套方法
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Stack Overflow用户

提问于 2019-08-06 00:53:59

回答 2查看 1.7K关注 0票数 0

为这事绞尽脑汁。我想模拟下面的生成器方法self.api.redditor(username).comments.new(limit=num)和self.api.redditor(username).submissions.new(limit=num)，其中self.api被分配给一个类实例，就像在self.api = PrawReddit()中一样

我正在尝试测试结果的大小：self.assertEqual(len(result), 5)

到目前为止，我尝试了MockPraw.return_value.redditor.return_value.comments.return_value.new.return_value.__iter__.return_value = iter(['c' * 10])，但使用AssertionError: 0 != 5测试失败

任何建议都非常感谢。

def get_comments_submissions(self, username, num=5):
    """Return max `num` of comments and submissions by `username`."""
    coms = [
        dict(
            title=comment.link_title,
            text=comment.body_html,
            subreddit=comment.subreddit_name_prefixed,
            url=comment.link_url,
            created=datetime.fromtimestamp(comment.created_utc, pytz.utc),
        )
        for comment in self.api.redditor(username).comments.new(limit=num)
    ]
    subs = [
        dict(
            title=submission.title,
            text=submission.selftext_html,
            subreddit=submission.subreddit_name_prefixed,
            url=submission.url,
            created=datetime.fromtimestamp(submission.created_utc, pytz.utc),
        )
        for submission in self.api.redditor(username).submissions.new(limit=num)
    ]
    return coms + subs if len(coms + subs) < num else (coms + subs)[:num]

mocking

generator

python-unittest

python

unit-testing

回答 2

Stack Overflow用户

回答已采纳

发布于 2019-08-06 01:24:46

要模拟生成器(除非您正在使用特定的生成器特性)，您可以使用迭代器作为替代，例如

import unittest.mock as mock

generator_mock = Mock(return_value=iter(("foo", "bar")))

当你有嵌套结构时，比如你的例子，这会变得有点复杂，属性访问是自动处理的，但是必须定义来自函数的return_value。从您的示例中可以看出：

# API mock
mock_api = Mock()
mock_api.redditor.return_value = mock_subs = Mock()

# Submissions mock
mock_subs.new.return_value = iter(("foo", "bar"))

然后可以调用并断言这一点

for item in mock_api.api.redditor("user").submissions.new(limit=5):
    print(item)

mock_api.redditor.assert_called_with("user")
mock_subs.new.assert_called_with(limit=5)

由于API是同一类的成员，因此必须对其进行猴子修补，例如：

target = Praw()
target.api = mock_api()
target.get_comments_submissions("user")

mock_api.redditor.assert_called_with("user")
mock_subs.new.assert_called_with(limit=5)

请注意，返回值中的iterator是一个实例，第二次调用get迭代器将返回相同的实例。

票数 1

Stack Overflow用户

发布于 2019-08-06 01:32:47

像使用pytest-mock一样编写，所有事情都在mymodule中发生(您在模块顶部导入了类，如from xy import PrawReddit)：

mocker.patch("datetime.fromtimestamp")
mocked_comment = mocker.MagicMock()
mocked_submission = mocker.MagicMock()
mocked = mocker.patch("mymodule.PrawReddit")
mocked.return_value.redditor.return_value.comments.new.return_value = [mocker.MagicMock(), mocked_comment]
mocked.return_value.redditor.return_value.submisions.new.return_value = [mocker.MagicMock(), mocked_submission]

returned = instance.get_comments_submissions("foo", num=2)
assert mocked.return_value.redditor.call_count = 2
mocked.return_value.assert_called_with("foo")
assert returned[-1]["link_title"] == mocked_comment.link_title

另一个带有相同简介的测试调用：

# ...
returned = instance.get_comments_submissions("foo")
assert mocked.return_value.redditor.call_count = 2
mocked.return_value.assert_called_with("foo")
assert returned[1]["link_title"] == mocked_comment.link_title
assert returned[-1]["title"] == mocked_submission.title