Version specification for black makes poetry fail

[wasdee]

It seems like poetry doesn't understand * version.

 poetry add --dev darker
Using version ^1.0.0 for darker

Updating dependencies
Resolving dependencies...

[SolverProblemError]
Because no versions of darker match >1.0.0,<2.0.0
 and darker (1.0.0) depends on black (*), darker (>=1.0.0,<2.0.0) requires black (*).
So, because no versions of black match *
 and gebwai-backend depends on darker (^1.0.0), version solving failed.

[akaihola]

Hi @CircleOnCircles,

Thanks for the report!

I looked but didn't yet find out where the * asterisk comes from.

In darker 1.0.0 setup.cfg we have:

install_requires =
    black
    typing-extensions ; python_version < "3.8"

Looking inside darker-1.0.0-py3-none-any.whl on PyPI, we have:

$ unzip -p darker-1.0.0-py3-none-any.whl darker-1.0.0.dist-info/METADATA|grep Requires-Dist
Requires-Dist: black
Requires-Dist: typing-extensions ; python_version < "3.8"
Requires-Dist: isort (>=5.0.1) ; extra == 'isort'
Requires-Dist: pytest ; extra == 'test'
Requires-Dist: pytest-black ; extra == 'test'
Requires-Dist: pytest-isort (>=1.1.0) ; extra == 'test'
Requires-Dist: pytest-mypy ; extra == 'test'

and in darker-1.0.0.tar.gz:

$ tar xOf darker-1.0.0.tar.gz darker-1.0.0/setup.cfg | grep -A3 install_requires
install_requires = 
	black
	typing-extensions ; python_version < "3.8"
python_requires = >=3.6

$ tar xOf darker-1.0.0.tar.gz darker-1.0.0/src/darker.egg-info/requires.txt                    
black

[:python_version < "3.8"]
typing-extensions

[isort]
isort>=5.0.1

[test]
pytest
pytest-black
pytest-isort>=1.1.0
pytest-mypy

[akaihola]

So @CircleOnCircles is this a Poetry bug (python-poetry/poetry#2687?) or can we do something in Darker to fix this problem?

[wasdee]

Yes, I guess.
At first, I thought we might be able to do a hotfix like specify the version. I had tried to explore the source code related to version dep. I came to the same conclusion as you.