Environment markers don't work with editable on local path?

Environment

• pip version: 20.1.1
• Python version: 3.6.9
• OS: Linux x86_64 (Ubuntu 18.04)

Description

This is a reply to/follow-up on #4530, as that issue is locked: it seems that quoting is needed when using markers on an editable install. This works when installing from a URL, but doesn’t seem to work when installing from a local file.

E.g. this works as expected:

-e 'git+http://example.com/NOT_EXISTING.git#egg=foo    ;  python_version >= "3.10"'

but this doesn’t:

-e 'path/to/local/project/    ;  python_version >= "3.10"'

Expected behavior path/to/local/project/ to not be installed

How to Reproduce Create a requirements.txt file with:

-e 'path/to/local/project/    ;  python_version >= "3.10"'

and install it with pip install -r requirements.txt.

Output

$  pip install -r requirements.txt
ERROR: path/to/local/project/    ;  python_version >= "3.10" is not a valid editable requirement. It should either be a path to a local project or a VCS URL (beginning with svn+, git+, hg+, or bzr+).

[uranusjr]

Editable is convenient for development, but IMO a “proper” package should be used in a tox environment. This would avoid you accidentally introduce package problems (especially manifest-related). IIRC tox can detect package updates and automatically re-install, so there’s not much benefit to use editable there.

[ghost]

… but IMO a “proper” package should be used in a tox environment …

For the record: I agree (though for packages only used for development/tests this can end up having a lower priority unfortunately), hence the “This is definitely not the best setup” 😉