Add a default session list

[duggelz]

Invoking nox with no command line arguments runs every session. It would be useful if the nox.py could specify a default list of sessions to run in that case, for example

nox.default_sessions([ 'lint', 'tests' ])

[duggelz]

CC @lukesneeringer

[lukesneeringer]

My suggestion is to actually make whether or not a session is a "default" session be part of session registration, e.g.

@nox.session(run_by_default=False)
def peekaboo(session):
    ...

This has a few limitations:

• It only works if you use the @nox.session decorator; if you rely on session_foo function names, no dice. I assert this is fine.
• There is no particularly good way to take a subset of parametrized sessions. So, in other words, while nox.default_sessions(["unit_tests(python_version='3.6')"]) would be easy (but eww!), it would be downright impossble if run_by_default only took a boolean. I assert this is also fine, and excluding parametrization should be done with session.skip
  • If we really needed this in the future, we could also make run_by_default accept a tuple with the permutations to run by default.

[theacodes]

I could go either way on this, but just noting that pytest's parametrize has pytest.param specifically for adding more information (marks) to individual runs:

# content of test_expectation.py
import pytest
@pytest.mark.parametrize("test_input,expected", [
    ("3+5", 8),
    ("2+4", 6),
    pytest.param("6*9", 42,
                 marks=pytest.mark.xfail),
])
def test_eval(test_input, expected):
    assert eval(test_input) == expected

If we want to go down the route that @lukesneeringer is suggesting we could do:

@nox.session
@nox.parametrize('foo, bar', [
     (1, 2),
     nox.param(3, 4, run_by_default=False)
])

[lukesneeringer]

If we did that, would the entire kaboodle be an initial requirement, or just the more general case?

[theacodes]

I'd strongly prefer a full solution over a partial one. It's also perhaps useful to just adopt pytest's marks. We could just have @nox.mark.default - if any thing is marked as default then running `nox` alone will only run those sessions, if nothing is marked as default then all sessions are run.

…

On Wed, Aug 30, 2017 at 2:13 PM Luke Sneeringer ***@***.***> wrote: If we did that, would the entire kaboodle be an initial requirement, or just the more general case? — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#40 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAPUc6wNjoAYHaDkitGJArzXyGA7YWQQks5sddBkgaJpZM4PH8RN> .

[lukesneeringer]

I could get behind @nox.mark.default so long as if nothing is marked default, they all are.

Should we change to @nox.mark.parametrize?

[theacodes]

Eh, I'd be okay with just nox.default and nox.parametrize. I don't think our API surface will be big enough to need to separate those into a mark namespace.

[pradyunsg]

Agreed. I don't think nox needs a complete mark namespace.

[stsewd]

I would love to have an env variable for this, tox has TOXENV, when it is defined and you run tox, only that environment is ran. For nox we could have NOXSESSION.

[theacodes]

@stsewd that would be much easier to do than this proposal, and could be done independently.

[sethmlarson]

I'm going to take a stab at implementing this, just signaling to anyone else if it's already in progress.

[theacodes]

Closing this in favor of #141, let's move the discussion there.