AttributeError: <module '__main__' from [..] 没有属性 'open' [英] AttributeError: <module '__main__' from [..] does not have the attribute 'open'

问题描述

我正在为 docker-py，但我似乎无法让测试正常工作.

我正在测试的函数如下所示:

def parse_env_file(env_file):"""读取以行分隔的环境文件.每行的格式应为key=value"."""环境 = []如果 os.path.isfile(env_file):使用 open(env_file, 'r') 作为 f:# 我们不能在这里使用 f.readlines() 因为它没有在 Mock 中实现对于 f.read().split('\n') 中的行:parse_line = line.strip().split('=')如果 len(parse_line) == 2 和 line[0] != '#':k = parse_line[0]v = parse_line[1]environment.append('{0}={1}'.format(k, v))返回环境

测试看起来像这样:

def test_parse_env_file_proper(self):使用 mock.patch('os.path.isfile', return_value=True):mock_env_file = 'USER=jdoe\nPASS=secret'使用 mock.patch('{}.open'.format(__name__), mock.mock_open(read_data=mock_env_file)):get_parse_env_file = parse_env_file('foobar')self.assertEqual(get_parse_env_file, ['USER=jdoe', 'PASS=secret'])

但是，当我运行测试时，出现以下错误:

======================================================================错误:test_parse_env_file_proper (__main__.UtilsTest)----------------------------------------------------------------------回溯(最近一次调用最后一次):文件tests/utils_test.py"，第 102 行，在 test_parse_env_file_proper 中使用 mock.patch('{}.open'.format(__name__), mock.mock_open(read_data=mock_env_file)):文件/Users/mvip/code/private/github/docker-py/.tox/py27/lib/python2.7/site-packages/mock.py"，第 1268 行，在 __enter__原始，本地 = self.get_original()文件/Users/mvip/code/private/github/docker-py/.tox/py27/lib/python2.7/site-packages/mock.py"，第1242行，在get_original%s 没​​有属性 %r" %(目标，名称)AttributeError: <module '__main__' from 'tests/utils_test.py'>没有属性打开"

这里的任何提示都会有所帮助.

解决方案

问题在于，作为内置函数，open 不能直接在模块中找到，而是作为 open 的后备代码>内置模块.

要解决这个问题，您应该在修补时包含 create=True.

from unittest import mock使用 mock.patch(__name__+".open", mock.mock_open(read_data="data"), create=True):with open("somefile") as f:断言 f.read() == 数据"

然而，这只是修补当前模块中的open(模块运行测试，而不是模块测试).>

所以你最好这样做:

导入单元测试从 unittest.mock 导入 mock_open，补丁导入模块_under_test定义函数():with open("somefile") as f:返回 f.read()类 MyTestCase(unittest.TestCase):def test_open(self):数据=一些数据"使用 patch.object(module_under_test, "open", mock_open(read_data=data), create=True):结果 = module_under_test.func()self.assertEqual(结果，数据)如果 __name__ == "__main__":单元测试.main()

I'm working on writing a test for a module for docker-py, but I can't seem to get the test to work properly.

The function I'm testing looks as follows:

def parse_env_file(env_file):
    """
    Reads a line-separated environment file.
    The format of each line should be "key=value".
    """
    environment = []

    if os.path.isfile(env_file):
        with open(env_file, 'r') as f:
            # We can't use f.readlines() here as it's not implemented in Mock
            for line in f.read().split('\n'):
                parse_line = line.strip().split('=')
                if len(parse_line) == 2 and line[0] != '#':
                    k = parse_line[0]
                    v = parse_line[1]
                    environment.append('{0}={1}'.format(k, v))

    return environment

The test then looks like this:

def test_parse_env_file_proper(self):
    with mock.patch('os.path.isfile', return_value=True):
        mock_env_file = 'USER=jdoe\nPASS=secret'
        with mock.patch('{}.open'.format(__name__), mock.mock_open(read_data=mock_env_file)):
            get_parse_env_file = parse_env_file('foobar')
    self.assertEqual(get_parse_env_file, ['USER=jdoe', 'PASS=secret'])

When I run the test however, I get the following error:

======================================================================
ERROR: test_parse_env_file_proper (__main__.UtilsTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "tests/utils_test.py", line 102, in test_parse_env_file_proper
    with mock.patch('{}.open'.format(__name__), mock.mock_open(read_data=mock_env_file)):
  File "/Users/mvip/code/private/github/docker-py/.tox/py27/lib/python2.7/site-packages/mock.py", line 1268, in __enter__
    original, local = self.get_original()
  File "/Users/mvip/code/private/github/docker-py/.tox/py27/lib/python2.7/site-packages/mock.py", line 1242, in get_original
    "%s does not have the attribute %r" % (target, name)
AttributeError: <module '__main__' from 'tests/utils_test.py'> does not have the attribute 'open'

Any pointers here would be helpful.

解决方案

The problem is that, as a builtin, open isn't directly found in the module, but rather as fallback in the builtins module.

To get around this you should include create=True when patching.

from unittest import mock

with mock.patch(__name__+".open", mock.mock_open(read_data="data"), create=True):
    with open("somefile") as f:
        assert f.read() == "data"

However, this only patches open in the current module (the module running the test, not the module under test).

So you'd be better off doing:

import unittest
from unittest.mock import mock_open, patch

import module_under_test


def func():
    with open("somefile") as f:
        return f.read()


class MyTestCase(unittest.TestCase):

    def test_open(self):
        data = "some data"
        with patch.object(module_under_test, "open", mock_open(read_data=data), create=True):
            result = module_under_test.func()

        self.assertEqual(result, data)


if __name__ == "__main__":
    unittest.main()

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