在 Python 测试中从 Python 脚本获取输出 [英] Getting output from Python script in Python tests

问题描述

我在文件bin/test"中有一个简单的 python 脚本:

#!/usr/bin/env python导入参数解析PROGRAM_NAME = "名称"PROGRAM_VERSION = "0.0.1"PROGRAM_DESCRIPTION = "desc"parser = argparse.ArgumentParser(prog=PROGRAM_NAME, description=PROGRAM_DESCRIPTION)parser.add_argument('--version', action='version', version='%(prog)s' + PROGRAM_VERSION)args = parser.parse_args()

当我使用 --version 参数或 --help 运行它时，它会打印出一切正常:

$ bin/test --version名称 0.0.1$ bin/test --help用法:名称 [-h] [--version]描述可选参数:-h, --help 显示此帮助信息并退出--version 显示程序的版本号并退出

当我使用 subprocess.check_output 运行文件时，它什么也没得到:

<预><代码>>>>subprocess.check_output(["bin/test", "--help"], stderr=subprocess.STDOUT, shell=True)''>>>subprocess.check_output(["bin/test", "--version"], stderr=subprocess.STDOUT, shell=True)''

我使用的是 Ubuntu 11.10 和 Python 版本:

python --version蟒蛇 2.7.1+

我需要在测试中获取脚本输出.我该怎么做?

解决方案

如果您使用 shell=True，请不要将程序及其参数作为列表传递.这有效:

subprocess.check_output("bin/test --help", stderr=subprocess.STDOUT, shell=True)

当然，将 shell 保留为 False 也可以.

Edit2:文档解释了原因

<块引用>

在 Unix 上，shell=True:如果 args 是一个字符串，它指定通过 shell 执行的命令字符串.这意味着字符串的格式必须与在外壳提示.这包括，例如，引用或反斜杠转义带有空格的文件名.如果 args 是一个序列，则第一项指定命令字符串，任何附加项都将被视为 shell 本身的附加参数.

I've got a simple python script in file 'bin/test':

#!/usr/bin/env python

import argparse

PROGRAM_NAME        = "name"
PROGRAM_VERSION     = "0.0.1"
PROGRAM_DESCRIPTION = "desc"
parser = argparse.ArgumentParser(prog=PROGRAM_NAME, description=PROGRAM_DESCRIPTION)
parser.add_argument('--version', action='version', version='%(prog)s ' + PROGRAM_VERSION)

args = parser.parse_args()

When I run it with the --version param, or --help, it prints everything OK:

$ bin/test --version
name 0.0.1

$ bin/test --help
usage: name [-h] [--version]

desc

optional arguments:
  -h, --help  show this help message and exit
  --version   show program's version number and exit

When I run the file using subprocess.check_output, it doesn't get anything:

>>> subprocess.check_output(["bin/test", "--help"],  stderr=subprocess.STDOUT, shell=True)
''
>>> subprocess.check_output(["bin/test", "--version"],  stderr=subprocess.STDOUT, shell=True)
''

I'm using Ubuntu 11.10 with Python version:

python --version
Python 2.7.1+

I need to get the script output in tests. How should I do that?

解决方案

If you're using shell=True, don't pass the program and its arguments as a list. This works:

subprocess.check_output("bin/test --help",  stderr=subprocess.STDOUT, shell=True)

Edit: of course, leaving shell as False would have worked too.

Edit2: the documentation explains why

On Unix, with shell=True: If args is a string, it specifies the command string to execute through the shell. This means that the string must be formatted exactly as it would be when typed at the shell prompt. This includes, for example, quoting or backslash escaping filenames with spaces in them. If args is a sequence, the first item specifies the command string, and any additional items will be treated as additional arguments to the shell itself.

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