pathlib.py:在Windows上实例化'PosixPath‘

Question

我从克隆了的源代码(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以供开发：

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

效果很好。之后，尝试通过以下方式运行测试：

py.test

得到以下错误：

================================== 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>

我怀疑这个工具只是写在Linux和类unix命令行上。

• 造成这个错误的原因是什么？
• 如果它是未在Windows上实现的python库的一部分，那么有什么快速修复吗？

我想开始从事开源项目，成为一个更好的开发人员。在我的开发任务中使用Linux并不是问题。如果我知道更有经验的开发人员对此的意见，这将对我有帮助。

Answer 1

造成此错误的原因是，在Windows上，PosixPath没有实现。但是有PurePosixPath，您可以在任何地方使用PosixPath来独立于平台处理POSIX路径。或者，您可能实际上希望拥有平台相关的路径(即在Linux上使用/，在Windows上使用\ )，在这种情况下，您应该只使用Path。

来自文档 (在继承图下面)：

纯路径在某些特殊情况下是有用的；例如：

1. 如果您想在Unix机器上操作Windows路径(反之亦然)。在Unix上运行时不能实例化WindowsPath，但可以实例化PureWindowsPath。