feat: cobra-cli support

[EmilyGraceSeville7cf]

Description

https://github.com/spf13/cobra-cli/blob/main/README.md

Fixes issue #

TODOs:

• Changes to fish usage are reflected in user documentation/manpages.
• Tests have been added for regressions fixed
• User-visible changes noted in CHANGELOG.rst

[EmilyGraceSeville7cf]

I expected eval (cobra-cli completion fish) to work, but it didn't for some reason: no completion appeared after this command was entered in the interactive Fish session. Can somebody explain why it failed to work? cobra-cli completion fish writes output to stdout, so I expected eval to correctly interpret its output. What am I missing?

[faho]

What you actually want is a third thing:

cobra-cli completion fish | source

This is also what our completions for e.g. starship or deno do

Here's why eval didn't work:

echo "echo foo
echo bar" > script

Now run eval (cat script). This ends up running eval "echo foo" "echo bar", only eval doesn't care about separate arguments (if it did eval echo foo would run an empty echo and then a command foo). It ends up running echo foo echo bar, printing "foo echo bar".

The first line of the output of cobra-cli completion fish is a comment, so eval sees one big comment and does nothing.

[faho]

Thanks!