Consider a .[dev] optional extra in setup.cfg

[FollowTheProcess]

How would this feature be useful?

When developing against nox, I like to create a virtual environment and install the project in editable mode with all the linters and formatters etc. so VSCode helps me out with mypy and things like that. Currently I do something along the lines of:

python -m venv .venv
source .venv/bin/activate.fish

python -m pip install --upgrade pip setuptools wheel
python -m pip install -e .
python -m pip install -r requirements-test.txt
python -m pip install -r requirements-conda-test.txt

Some of this probably isn't necessary? But I like to have everything in my environment 🤓

Describe the solution you'd like

If we put a [dev] optional extra in setup.cfg a user can simply do python -m pip install -e .[dev] to get everything needed in one easy command.

This would look like:

[options.extras_require]
dev =
    <Contents of requirements files>

Describe alternatives you've considered

Just continue using my list of commands.

[cjolowicz]

You could achieve the same with a requirements-dev.txt, no? It can reference the others and perform an editable install of Nox. There is no need to change the package metadata this way.

[FollowTheProcess]

That works too 👍🏻

[ktbarrett]

I actually like using nox for this.

@nox.session(reuse_venv=True)
def dev(session):
    session.install("pytest", "black", "isort", "mypy")
    session.install("-e", ".")
    if session.posargs:
        session.run(*session.posargs, external=True)

Now you can use it.

nox -e dev  # builds the environment
. .nox/dev/bin/activate  # activates it

or...

nox -e dev -- bash
# you are now in your environment, only an "exit" away from cleanup

[FollowTheProcess]

@ktbarrett Check out the dev session in the cookbook it's very similar!

Coming back to this. Are we interested in a requirements-dev.txt? It's a pretty cheap thing for a small improvement in DX, but not a dealbreaker if not

[DiddiLeija]

I made #582 for adding a requirements-dev.txt.