Tidy: detect ui tests subdirectory changes so tests/ui/README.md stays in sync

[reddevilmidzy]

close: #150399

There's an issue where tests/ui/README.md isn't updated whenever the ui subdirectory changes.
I've added subdirectory change detection to tidy added a new mention to triage.toml to notify tests/ui/README.md to also be updated.

r? @Urgau

[rustbot]

triagebot.toml has been modified, there may have been changes to the review queue.

cc @davidtwco, @wesleywiser

[Urgau]

Looks good to me, but I will let the final review to a T-bootstrap member.

Btw, could you make the title and description a bit more descriptive.

r? bootstrap

[reddevilmidzy]

Okay, thank you for the review:)

[Zalathar]

I don't quite understand the purpose of having a separate ui_suites.txt.

If the goal is to keep tests/ui/README.md in sync with the subdirectories, wouldn't it make more sense to compare the list of subdirectories to the list of headings in the readme?

[reddevilmidzy]

I don't quite understand the purpose of having a separate ui_suites.txt.

If the goal is to keep tests/ui/README.md in sync with the subdirectories, wouldn't it make more sense to compare the list of subdirectories to the list of headings in the readme?

Ah, since the initial suggestion was to "add comments when subdirectories change," so we implemented it by creating a ui_suites.txt file so that triagebot could leave comments.

If we wanted to include directory change detection in tidy and force modifications to tests/ui/README.md, comparing the subtitles of tests/ui/README.md would be a better approach, as you suggested.

I will change it.

[Urgau]

I don't quite understand the purpose of having a separate ui_suites.txt.

If the goal is to keep tests/ui/README.md in sync with the subdirectories, wouldn't it make more sense to compare the list of subdirectories to the list of headings in the readme?

Parsing a Markdown file is non-trivial and tidy currently doesn't have a dependency on pulldown-cmark. I'm not sure we would want to add such dependency to tidy, so we would have to approximate it.

But in general yes, looking at tests/ui/README.md is probably better.

[Zalathar]

Given that this is an in-tree tidy check for a single file that we already control, I don't think we need to actually parse Markdown.

We can just assume that tests/ui/README.md will be written in a predictable style, and use a relatively-simple regex to extract directory names from lines that start with ##.

If somebody tries to modify the readme in a way that would break the tidy check, well, maybe they shouldn't be doing that.

[Zalathar]

@rustbot author