如何编写OSError的单元测试？ [英] How do I write a unit test for OSError?

问题描述

我有以下要测试的python代码：

I have the following python code which I want to test:

def find_or_make_logfolder(self):
    if not path.isdir(self.logfolder):
        try:
            makedirs(self.logfolder)
        except OSError:
            if not path.isdir(self.logfolder):
                raise

我想在单元测试中执行以下操作。

I want to do something like the following in my unittest.

def test_find_or_make_logfolder_pre_existing(self):
    with self.assertRaises(OSError):
        makedirs(self.logfolder)
        find_or_make_logfolder()

但是，如果不是path.isdir（self.logfolder） ：正在检查目录是否已经存在，以便 OSError 除外，仅在程序或人员成功执行的情况下抛出使目录在 if try 之前几毫秒。

However, if not path.isdir(self.logfolder): is checking if the directory already exists or not so that the except OSError will only be thrown in some edge case where a program or person succeeds in making the directory a few milliseconds after the if and before the try.

如何o我对此进行测试，还是真的需要对此进行测试？

How do I test this, or do I really need to test this?

当覆盖率达到100％时，我倾向于喜欢它。

I tend to like it when coverage says 100%.

推荐答案

您可以采用更Python化的方法来实现这一目标。在Python中，哲学是

You could go a more Pythonic route to achieve this. In Python the philosophy is

寻求宽恕比寻求许可要好。

It's better to ask for forgiveness than to ask for permission.

请参见此处的EAFP

请记住，您的代码可以编写如下：

With that in mind, your code could be written as follows:

def find_or_make_logfolder(self):
    try:
        makedirs(self.logfolder)
    except OSError:
        #self.logfolder was already a directory, continue on.
        pass

现在要覆盖此代码的100％，您只需创建目录已经存在的测试案例。

Now to get 100% of this code covered, you will just need to create a test case where the directory already exists.

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