Have friendlier message if no noxfile.py found.

[FollowTheProcess]

How would this feature be useful?

If you run nox in a directory with no noxfile.py you get a scary looking exception:

This is clearly the intended behaviour as using nox without a noxfile is a bit of a non-starter to say the least, and most people could easily figure out what it's trying to tell you, but this traceback is somewhat distracting and slightly off-putting (especially to newer python developers).

A friendlier message could just provide a nicer experience for people new to this whole thing.

Describe the solution you'd like

If nox hits a FileNotFoundError whilst trying to load noxfile.py it could instead return a friendlier log message without the traceback along the lines of "no noxfile.py found in current directory, create one and try again." with maybe a link to the docs or something like that?

It could perhaps even generate a "hello world" style placeholder noxfile along the lines of:

import nox


@nox.session
def hello(session: nox.Session):
    """
    Your first nox session!
    """
    session.log("Hello world!")

But that might be unnecessary I don't know, keen for maintainers input here!

This seems pretty simple to implement and I'd be more than happy to submit a PR if this is something you'd like?

Thanks!

[cjolowicz]

Thanks for raising this, PR welcome! I'd suggest to keep it simple, along the lines of "noxfile.py not found".