Add clear_fmt_recursive method

[nicopap]

When comparing two different KdlNode or KdlDocument, it's useful to
have a "canonical" representation where formatting differences do not
matter.

clear_fmt removes all formatting from a KdlNode, but does not apply
recursively, as a result, it doesn't create a canonical representation.
clear_fmt_recursive solves this by applying clear_fmt recursively to
the contents of the node.

[nicopap]

@zkat May I get your attention? You might have overlooked this PR.

[zkat]

Oh sorry, I did miss this.

So what you want here is to use something that will wipe out comments, not just format everything into a "standard" format?

[nicopap]

Yeah, I'd like to whip out comments. But it's not because I want to print it, it's more to do with equality and testing.

The idea is to have a representation that only depends on the actual values of the nodes. It's useful for two things: testing and comparing two different KdlNode.

The #[derive(PartialEq)] means that when comparing two KdlNode, even formatting differences will make them unequal. A method to get rid of all formatting (recursively) enables comparing them independently of formatting. The current clear_fmt is not enough, since nested nodes will not be "deformatted" and will be unequal despite equal values.

It's also useful for testing. The output of assert_eq! (even from the pretty_assertions crate) is difficult to read visually when comparing KdlNode, because there is all the formatting-related fields on the debug output. Simply translating the KdlNode to a "deformatted" string makes the diff much easier to read.

I wrote my own clear_fmt_recursive for my tests here https://github.com/nicopap/bevy-kdl-ui/blob/2ba1833f38178fb7ddfbf39f203be6a766fe59bc/template-kdl/tests/readme-examples.rs#L82-L83 and it helped me fix my own bugs much quicker.

[zkat]

sgtm :)

[zkat]

this has been published as part of [email protected] :)

So great that you're using it!