pathlib.py：在 Windows 上实例化 'PosixPath'

Question

我从 its repository 克隆了 thefuck 源代码（这是真正的项目名称，是的，我知道...）。尝试通过以下命令安装它进行开发：

pip install -r requirements.txt
python setup.py develop

它运行良好。之后尝试运行测试：

py.test

出现以下错误：

================================== FAILURES ===================================
_______________________________ test_load_rule ________________________________

mocker = <pytest_mock.MockFixture object at 0x03275A10>

    def test_load_rule(mocker):
        match = object()
        get_new_command = object()
        load_source = mocker.patch(
            'thefuck.main.load_source',
            return_value=Mock(match=match,
                              get_new_command=get_new_command,
                              enabled_by_default=True,
                              priority=900))
        assert main.load_rule(Path('/rules/bash.py')) \
               == Rule('bash', match, get_new_command, priority=900)
>       load_source.assert_called_once_with('bash', '/rules/bash.py')

tests\test_main.py:20:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
C:\Python34\lib\unittest\mock.py:782: in assert_called_once_with
    return self.assert_called_with(*args, **kwargs)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_mock_self = <MagicMock name='load_source' id='52977776'>
args = ('bash', '/rules/bash.py'), kwargs = {}
expected = (('bash', '/rules/bash.py'), {})
_error_message = <function NonCallableMock.assert_called_with.<locals>._error_me
ssage at 0x032A1030>
actual = call('bash', '\rules\bash.py'), cause = None

    def assert_called_with(_mock_self, *args, **kwargs):
        """assert that the mock was called with the specified arguments.

            Raises an AssertionError if the args and keyword args passed in are
            different to the last call to the mock."""
        self = _mock_self
        if self.call_args is None:
            expected = self._format_mock_call_signature(args, kwargs)
            raise AssertionError('Expected call: %s\nNot called' % (expected,))

        def _error_message():
            msg = self._format_mock_failure_message(args, kwargs)
            return msg
        expected = self._call_matcher((args, kwargs))
        actual = self._call_matcher(self.call_args)
        if expected != actual:
            cause = expected if isinstance(expected, Exception) else None
>           raise AssertionError(_error_message()) from cause
E           AssertionError: Expected call: load_source('bash', '/rules/bash.py')

E           Actual call: load_source('bash', '\rules\bash.py')

C:\Python34\lib\unittest\mock.py:771: AssertionError
__________________ TestGetRules.test_get[conf_rules0-rules0] __________________

self = <tests.test_main.TestGetRules object at 0x03286F50>
monkeypatch = <_pytest.monkeypatch.monkeypatch object at 0x03286CD0>
glob = <MagicMock name='glob' id='52981200'>, conf_rules = []
rules = ['bash', 'lisp', 'bash', 'lisp']

    @pytest.mark.parametrize('conf_rules, rules', [
        (conf.DEFAULT_RULES, ['bash', 'lisp', 'bash', 'lisp']),
        (types.RulesNamesList(['bash']), ['bash', 'bash'])])
    def test_get(self, monkeypatch, glob, conf_rules, rules):
>       glob.return_value = [PosixPath('bash.py'), PosixPath('lisp.py')]

tests\test_main.py:35:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

cls = <class 'pathlib.PosixPath'>, args = ('bash.py',), kwargs = {}
self = PosixPath('bash.py')

    def __new__(cls, *args, **kwargs):
        if cls is Path:
            cls = WindowsPath if os.name == 'nt' else PosixPath
        self = cls._from_parts(args, init=False)
        if not self._flavour.is_supported:
            raise NotImplementedError("cannot instantiate %r on your system"
>                                     % (cls.__name__,))
E           NotImplementedError: cannot instantiate 'PosixPath' on your system

C:\Python34\lib\site-packages\pathlib-1.0.1-py3.4.egg\pathlib.py:939: NotImpleme
ntedError
__________________ TestGetRules.test_get[conf_rules1-rules1] __________________

self = <tests.test_main.TestGetRules object at 0x032BAB50>
monkeypatch = <_pytest.monkeypatch.monkeypatch object at 0x03275A30>
glob = <MagicMock name='glob' id='53194576'>, conf_rules = ['bash']
rules = ['bash', 'bash']

    @pytest.mark.parametrize('conf_rules, rules', [
        (conf.DEFAULT_RULES, ['bash', 'lisp', 'bash', 'lisp']),
        (types.RulesNamesList(['bash']), ['bash', 'bash'])])
    def test_get(self, monkeypatch, glob, conf_rules, rules):
>       glob.return_value = [PosixPath('bash.py'), PosixPath('lisp.py')]

tests\test_main.py:35:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

cls = <class 'pathlib.PosixPath'>, args = ('bash.py',), kwargs = {}
self = PosixPath('bash.py')

    def __new__(cls, *args, **kwargs):
        if cls is Path:
            cls = WindowsPath if os.name == 'nt' else PosixPath
        self = cls._from_parts(args, init=False)
        if not self._flavour.is_supported:
            raise NotImplementedError("cannot instantiate %r on your system"
>                                     % (cls.__name__,))
E           NotImplementedError: cannot instantiate 'PosixPath' on your system

C:\Python34\lib\site-packages\pathlib-1.0.1-py3.4.egg\pathlib.py:939: NotImpleme
ntedError
______________________________ test_side_effect _______________________________

ssh_error = ('@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@\n@
WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!  ...own_hosts', <function ssh_e
rror.<locals>.reset at 0x033F16F0>, <function ssh_error.<locals>.known_hosts at
0x033F1198>)

    def test_side_effect(ssh_error):
        errormsg, path, reset, known_hosts = ssh_error
        command = Command('ssh user@host', stderr=errormsg)
        side_effect(command, None)
        expected = ['123.234.567.890 asdjkasjdakjsd\n', '111.222.333.444 qwepoiw
qepoiss\n']
>       assert known_hosts(path) == expected
E       assert ['123.234.567...oiwqepoiss\n'] == ['123.234.567....oiwqepoiss\n']

E         At index 1 diff: '98.765.432.321 ejioweojwejrosj\n' != '111.222.333.44
4 qwepoiwqepoiss\n'
E         Left contains more items, first extra item: '111.222.333.444 qwepoiwqe
poiss\n'
E         Use -v to get the full diff

tests\rules\test_ssh_known_host.py:61: AssertionError
=============== 4 failed, 122 passed, 2 skipped in 0.56 seconds ===============

C:\code\thefuck>

我怀疑这个工具被编写成只能在 Linux 和类 unix 命令行上工作。

这个错误的原因是什么？
如果它是 python 库的一部分，但未针对 Windows 实现，是否有任何快速修复？

我想开始从事开源项目，以成为更好的开发人员。对我的开发任务使用 Linux 不是问题。如果我知道更多有经验的开发人员对此的意见，将会对我有所帮助。

Answer 1

这个错误的原因是，Windows，PosixPath没有实现。但是有 PurePosixPath，你可以在任何你想使用 PosixPath 的地方使用它来独立处理 POSIX 路径。或者，您可能实际上想要拥有依赖于平台的路径（即 Linux 上的 / 和 Windows 上的 \），在这种情况下您应该使用 Path.

来自documentation（继承关系图下方）：

Pure paths are useful in some special cases; for example:

If you want to manipulate Windows paths on a Unix machine (or vice versa). You cannot instantiate a WindowsPath when running on Unix, but you can instantiate PureWindowsPath.

pathlib.py：在 Windows 上实例化 'PosixPath'

pathlib.py: Instantiating 'PosixPath' on Windows

python

windows

posix

python-3.x

pathlib