How would this feature be useful?

Currently, Nox builds and installs a fresh wheel for every session. That is slow & unnecessary for 99.999% of situations.

Describe the solution you'd like

I'd like something akin to tox's

[testenv]
package = wheel
wheel_build_env = .pkg

(see also https://hynek.me/articles/turbo-charge-tox/)

so I can say that one wheel is plenty for all environments, like

nox.options.one_wheel_for_all = True

I don't think Nox needs as fine-grained controls like tox has – courtesy of Python. But this one use case is common enough to save a lot of CPU and IO cycles.

Describe alternatives you've considered

You can do it by hand, either by passing an argument:

@nox.session
def tests(session):
    posargs = list(session.posargs)

    try:
        i = posargs.index("--installpkg")
        pkg = posargs[i + 1]
        del posargs[i : i + 2]
    except ValueError:
        pkg = "."

    session.install(pkg)

Or an explicit environment:

@nox.session
def build(session: nox.Session) -> None:
    shutil.rmtree("dist", ignore_errors=True)
    session.install("build")
    session.run("python", "-m", "build")


@nox.session(python=[...])
def tests(session: nox.Session) -> None:
    (wheel,) = Path("dist").glob("*.whl")

    session.install(wheel, "coverage[toml]")

    session.run("coverage", "run", "-m", "pytest", *session.posargs)

    if os.environ.get("CI") != "true":
        session.notify("coverage_report")

But but both require manual intervention and present sharp edges. E.g. calling nox -s tests -p 3.11 won't rebuild the package and will run the tests against outdated code.

If this would be handled by Nox, I would expect it to make sure the wheel is built when I call session.install('.')

Anything else?

No response