🐛 Ensure that an envvar set for a typer.Option list is split on whitespace

[svlandeg]

Fixes #1789, thanks to @wpk-nist-gov for the report.

Description

This bug fix is related to #1787 though not quite the same. A user reported that this doesn't work anymore:

def from_option(user: Annotated[list[str], typer.Option(envvar="ME")]):
    print(f"Hello {user}")

As far as I know, we don't actually document using envvar in combination with a list type. Before 0.26.0, Click's defaults would parse the envvar string on whitespace and produce a list when calling this with something like env={"ME": "rick morty"}.

This currently still works for Argument as it doesn't have its own implementation of value_from_envvar, it still uses Click's old one from Parameter. For Option, this functionality was removed in the refactor. This PR restores the functionality for Option in a quick bug fix PR. Argument and Option should work similarly, which is now the case with this PR. For the future, we should consider whether we want to keep & document this behaviour.

AI Disclaimer

Used Cursor to help me debug the issue more quickly, manually reviewed everything in detail.

Checklist

• I added tests for the change.
• The new or updated tests fail on the main branch and pass on this PR.
• Coverage stays at 100%.

[wpk-nist-gov]

For what it's worth, this behavior is documented for click (which is where I got the idea from). Thanks again for your help @svlandeg!

[svlandeg]

For what it's worth, this behavior is documented for click (which is where I got the idea from).

Yes, but the point is that it's not documented for Typer. And going forward after the vendoring, only what is documented by Typer is considered to be part of Typer's public API. So, if this is a feature we want to explicitly support and test, we should also document it.

(But that's considered follow-up work & decisions as we have tried to be as minimally breaking for now)