imagefilter: add SupportedOutputFormats

[schuellerf]

Convenience function for concise help output

(This is based on #1166 and #1167)

The last commit could be split off, it's not directly related to the implementation of SupportedOutputFormats just extends the tests

[mvo5]

Thank you! I like the idea of having the SupportedOutputFormats() helper. Some suggestions for the implementation inline.

[mvo5]

Quick drive-by:

1. the PR description should follow the convention: module: change (e.g. imagefilter: add SupportedOutputFormats)
2. Rebasing this on top of main and dropping the diff for the "short" output would most likely get this merged much quicker as I feel "short" output will need some more design/discussion but this here is very nice and straightforward.

[supakeen]

Two notes:

1. We normally don't use Hungarian notation; e.g. writing the type (Map) in the variable name and personally I don't like it.
2. The behavior here is slightly different because all key lookups now return the same instance of a formatter. Since formatters don't keep state (right now) this might be OK, just wanted to write it down as it's a behavioral change I think?

[mvo5]

Thanks for the careful review. I think this is fine because currently the formatters are an empty map, once we add state the map would become a map[string]func() Foramtter most likely to generate the new things (we could do it today but see below).

A fun fact of go is that empty structs get optimized away by the go-compiler, so at least on my system:

func TestNewDifferentObj(t *testing.T) {
	fmt1, err := imagefilter.NewResultsFormatter(imagefilter.OutputFormatText)
	assert.NoError(t, err)
	fmt2, err := imagefilter.NewResultsFormatter(imagefilter.OutputFormatText)
	assert.NoError(t, err)
	assert.NotEqual(t, fmt1, fmt2)
}

is false even with the current implementation that creates a "new" formatter with every new() call.

This is a long winded way of saying, I'm okay with as it is but open for ideas.

[supakeen]

Some minor questions and bits.

[supakeen]

the PR description should follow the convention: module: change (e.g. imagefilter: add SupportedOutputFormats)

I noticed the commits are now prefixed with the full package path instead of the module name. I don't know how I feel about this :)

[schuellerf]

oh - that shouldn't happen?
https://github.com/osbuild/images/actions/runs/13071656708/job/36474442726?pr=1168
we are supposed to support 1.22, right?

go: github.com/vmware/govmomi/[email protected] requires go >= 1.23; switching to go1.23.5
go: downloading go1.23.5 (linux/amd64)

should I downgrade that lib so it works with 1.22?

[supakeen]

SupportedFormatters (the type is already a map) is the only bit.

[schuellerf]

grr - overlooked that one, thanks

[mvo5]

Thank you