bpo-35022: Add __fspath__ support to unittest.mock.MagicMock

[maxbelanger]

This is a naive implementation of what has been working for us internally.

https://bugs.python.org/issue35022

[vstinner]

@mariocj89: Would you mind to review this change?

[vstinner]

LGTM. But I would prefer to have a second review, @mariocj89?

[mariocj89]

LGTM! Feels a little "weird" but I guess there is no better way, I've added some minor suggestions in case you find them useful @vstinner

[mariocj89]

This will elide all naming information. See:

>>> os.fspath(m.absolute)
'MagicMock/140083495922656'
>>> str(m.absolute)
"<MagicMock name='mock.absolute' id='140083495922656'>"

Or when a mock is given a name. The id is unique per attribute and probably quite unuseful for the user when debugging issues.

Have you considered:
lambda self: f"{self._extract_mock_name()}/{id(self)}"

It would look nicer in some scenarios like:

>>> os.fspath(mock.MagicMock(**{"__fspath__.return_value": "abc"}).absolute)
'mock.absolute/140476946856592'

But maybe weird for some others like:

>>> os.fspath(mock.MagicMock() / 'other' / 'path')
'mock.__truediv__().__truediv__()/140476946879824'

[maxbelanger]

Agree that naming information should be preserved, what would you think of:

lambda self: f"{type(self).__name__}/{self._extract_mock_name()}/{id(self)}"

The __truediv__ case is a bit strange but it is correct, though.

[vstinner]

@mariocj89: does it look better to you?

[mariocj89]

Sure! I think it will be easier to debug. :)

[vstinner]

Sure! I think it will be easier to debug. :)

I mean: can you please review the updated PR? Like approving it if you consider that it now looks good to you?

[mariocj89]

Much better indeed! :)