未关闭但UnitTest正在抛出它的文件的ResourceWarning [英] ResourceWarning for a file that is unclosed but UnitTest is throwing it

问题描述

我有一个这样的功能:

def init_cars(self, directory=''):
    #some_code
    cars = set([line.rstrip('\n') for line in open(directory + "../myfolder/all_cars.txt")])
    #some_more_code

我正在编写 unittest，当我运行它们时，出现以下错误:

I am writing unittest and when I run them, I get the following error:

ResourceWarning: unclosed file <_io.TextIOWrapper name='../myfolder/all_cars.txt' mode='r' encoding='UTF-8'>
  names = set([line.rstrip('\n') for line in open(directory + "../myfolder/all_cars.txt")])
ResourceWarning: Enable tracemalloc to get the object allocation traceback

找到了一个答案，但不能应用于我可以解决的代码:Python 3:ResourceWarning:未关闭的文件 <_io.TextIOWrapper name='PATH_OF_FILE'

Found an answer but can't apply to my code that I can work out: Python 3: ResourceWarning: unclosed file <_io.TextIOWrapper name='PATH_OF_FILE'

我尝试了一些东西，做了一些代码更改，但似乎无法弄清楚.谁能给我一个代码示例，告诉我如何使用我的示例代码解决这个问题！

I tried a few things, made some code changes but can't seem to figure out. Can anyone give me a code example on how to overcome this using my example code please!

推荐答案

当文件句柄不再被引用时，Python 不会自动为您关闭它.这是令人惊讶的.例如.

Python does not automatically close a filehandle for you when it is no longer referenced. This is surprising. For example.

def foo():
    f = open("/etc/passwd")
    for line in f:
        print(line)

即使在 foo() 返回后 f 不再可用，这也会导致 ResourceWarning.

This will result in a ResourceWarning even though f is no longer available once foo() returns.

解决方案是明确关闭文件.

The solution is to explicitly close the file.

fh = open(directory + "../myfolder/all_cars.txt")
cars = set([line.rstrip('\n') for line in fh]
fh.close()

或者使用 with将为您关闭文件.

Or use with which will close the file for you.

with open(directory + "../myfolder/all_cars.txt") as fh:
  cars = set([line.rstrip('\n') for line in fh]

这篇关于未关闭但UnitTest正在抛出它的文件的ResourceWarning的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！