I have tried 2 functions with different behavior across platform

# as_posix()

In linux platform, as_posix() cannot process window path nicely

* From linux + docker + python:3.8

```
Python 3.8.0 (default, Oct 17 2019, 05:36:36)
[GCC 8.3.0] on linux

>>> winPath = r'\workspace\xxx\test_fixture\user-restore-success.zip'
>>> posixPath = '/workspace/xxx/test_fixture/user-restore-success.zip'
>>> pWIN = pathlib.PurePath(winPath)
>>> pPOSIX = pathlib.PurePath(posixPath)
>>> pWIN.as_posix()
'\\workspace\\xxx\\test_fixture\\user-restore-success.zip'
>>> pPOSIX.as_posix()
'/workspace/xxx/test_fixture/user-restore-success.zip'
```

* From window + powershell + python3.6

```
Python 3.6.8 (tags/v3.6.8:3c6b436a57, Dec 24 2018, 00:16:47) [MSC v.1916 64 bit (AMD64)] on win32

>>> winPath = r'\workspace\xxx\test_fixture\user-restore-success.zip'
>>> posixPath = '/workspace/xxx/test_fixture/user-restore-success.zip'
>>> pWIN = pathlib.PurePath(winPath)
>>> pPOSIX = pathlib.PurePath(posixPath)
>>> pWIN.as_posix()
'/workspace/xxx/test_fixture/user-restore-success.zip'
>>> pPOSIX.as_posix()
'/workspace/xxx/test_fixture/user-restore-success.zip'

```

* From MAC

```
>>> winPath = '\\workspace\\xxx\\test_fixture\\user-restore-success.zip'
>>> posixPath = '/workspace/xxx/test_fixture/user-restore-success.zip'
>>> pWIN = pathlib.PurePath(winPath)
>>> pPOSIX = pathlib.PurePath(posixPath)
>>> pWIN.as_posix()
'\\workspace\\xxx\\test_fixture\\user-restore-success.zip'
>>> pPOSIX.as_posix()
'/workspace/xxx/test_fixture/user-restore-success.zip'
```

# resolve()

In window platform, resolve() returns absolute path only if such file is able to locate. Otherwise, it returns
relative path.

In Linux platform, resolve() returns absolute path anyway

* From linux

```
b4f03ed3003b">root@b4f03ed3003b:/var/run/lock# python
Python 3.8.0 (default, Oct 17 2019, 05:36:36)
[GCC 8.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import pathlib
>>> p = pathlib.Path('no_exists')
>>> p.resolve()
PosixPath('/run/lock/no_exists')
>>> str(p.resolve())
'/run/lock/no_exits'

```

* From window

```
Python 3.6.8 (tags/v3.6.8:3c6b436a57, Dec 24 2018, 00:16:47) [MSC v.1916 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import pathlib
>>> p = pathlib.Path('README.md')
>>> p.resolve()
WindowsPath('C:/Users/xxx/PycharmProjects/yyy/README.md')
>>> str(p.resolve())
'C:\\Users\\xxx\\PycharmProjects\\yyy\\README.md'
>>> p = pathlib.Path('no_exists')
>>> p.resolve()
WindowsPath('no_exists')
>>> str(p.resolve())
'no_exists'

```

Also, I have spotted a ticket similar to this one

https://bugs.python.org/issue41357

I'm not sure what you try to report.

PurePath(...) returns a PureWindowsPath on Windows and an PurePosixPath on other (unix-y) platforms. This explains the difference in behaviour you're seeing for as_posix().

Let me clarify my expectation.

# For `as_posix()`

* PureWindowsPath can translate both POSIX path, and WINDOW path to POSIX path via `as_posix()`
    * Therefore, I expect PurePosixPath can translate both platform path to POSIX path via `as_posix()`

* I just tried PurePosixPath() behave same between Window, and the docker.
    * I am sorry for showing misleading information

# For `resolve()`

* In window platform, resolve() returns absolute path only if such file is able to locate. Otherwise, it returns
relative path.

* In Linux platform, resolve() returns absolute path anyway

Moreover, output from PurePosixPath.as_posix() is not that straightforward?

Please take a look below example from python3.6 + linux + docker

```
>>> winPath = r'\workspace\xxx\test_fixture\user-restore-success.zip'

>>> pWIN = pathlib.PureWindowsPath(winPath)
>>> pppFromWinPath = pathlib.PurePosixPath(winPath)
>>> pppFromPwp = pathlib.PurePosixPath(pWIN)

>>> pppFromWinPath.as_posix()
'\\workspace\\xxx\\test_fixture\\user-restore-success.zip'
>>> pppFromPwp.as_posix()
'\\/workspace/xxx/test_fixture/user-restore-success.zip'
```

* Construction PurePosixPath from rawString, `as_posix()` gives '\\workspace\\xxx\\test_fixture\\user-restore-success.zip'
* Construction PurePosixPath from PureWindowsPath, `as_posix()` gives '\\/workspace/xxx/test_fixture/user-restore-success.zip'

PureWindowsPath does not know about POSIX paths, it supports the two styles of directory separator that are valid on Windows: '/' and '\'. 

PurePosixPath only supports the single stile of directory separator valid on POSIX systems: '/'. 

On a Posix system backslash is a valid character in a file name and is NOT a directory separator.


The behaviour of Path.resolve() on Windows may or may not be a bug, the documentation is not quite clear. Personally I'd lean toward saying this is a bug, but I defer to a pathlib expert.  Note that path.resolve(strict=True) should raise an error on both platforms when the path does not exists.

Thanks for the clarifications on PurePosixPath(). Now, I know which library I should use to solve my problem.

For resolve() with strict True, I have tried on both platform. They will both raise exception if that file does not exists.