remark-github autolink compare only works for sha commit?

[gagahpangeran]

These links are valid compare link in Github.

https://github.com/remarkjs/remark/compare/a3cc87c...cdab8fa
https://github.com/remarkjs/remark/compare/15.0.0...15.0.1
https://github.com/remarkjs/remark/compare/main...website
https://github.com/remarkjs/remark/compare/15.0.0...main
https://github.com/remarkjs/remark/compare/1d706ed...main
https://github.com/remarkjs/remark/compare/6a43da8...15.0.1

Result:

a3cc87c...cdab8fa
15.0.0...15.0.1
main...website
15.0.0...main
1d706ed...main
6a43da8...15.0.1

I use remark-github with this example.

import { remark } from "remark"
import remarkGfm from "remark-gfm"
import remarkGithub from "remark-github"

const content = `
https://github.com/remarkjs/remark/compare/a3cc87c...cdab8fa
https://github.com/remarkjs/remark/compare/15.0.0...15.0.1
https://github.com/remarkjs/remark/compare/main...website
https://github.com/remarkjs/remark/compare/15.0.0...main
https://github.com/remarkjs/remark/compare/1d706ed...main
https://github.com/remarkjs/remark/compare/6a43da8...15.0.1
`

const { value } = await remark()
  .use(remarkGfm)
  .use(remarkGithub, { repository: "remarkjs/remark" })
  .process(content)

console.log(value)

Output:

[`a3cc87c...cdab8fa`](https://github.com/remarkjs/remark/compare/a3cc87c...cdab8fa)
<https://github.com/remarkjs/remark/compare/15.0.0...15.0.1>
<https://github.com/remarkjs/remark/compare/main...website>
<https://github.com/remarkjs/remark/compare/15.0.0...main>
<https://github.com/remarkjs/remark/compare/1d706ed...main>
<https://github.com/remarkjs/remark/compare/6a43da8...15.0.1>

I expect the output is something like this.

[`a3cc87c...cdab8fa`](https://github.com/remarkjs/remark/compare/a3cc87c...cdab8fa)
[`15.0.0...15.0.1`](https://github.com/remarkjs/remark/compare/15.0.0...15.0.1)
[`main...website`](https://github.com/remarkjs/remark/compare/main...website)
[`15.0.0...main`](https://github.com/remarkjs/remark/compare/15.0.0...main)
[`1d706ed...main`](https://github.com/remarkjs/remark/compare/1d706ed...main)
[`6a43da8...15.0.1`](https://github.com/remarkjs/remark/compare/6a43da8...15.0.1)

Looks like the compare autolink only works when comparing two sha commit. Is this intentional?

I ask about this in this discussion page before creating an issue to confirm about this.
Thank you.

[wooorm]

Are these documented somewhere? I was not aware of them.

I guess these are also different because non-sha’s don’t “expand”: 15.0.0...15.0.1 stays plain text. Whereas a3cc87c...cdab8fa would become a link.

Functionality for the URL is here: https://github.com/remarkjs/remark-github/blob/9cd4e9d8fa6cd3520d11aa922462a0089e1204c5/lib/index.js#L142. The regex matches hexadecimal characters. It would be good to test which characters are allowed around ....

[gagahpangeran]

I only found small documentation about three-dot git diff comparison on Github in this page.

I also just found out that you can also do two-dot git diff comparison from that page.

I assume Github is using git diff for its two-dot and three-dot diff comparison. So any valid git commit SHA, branch name, or tag name are allowed.

I also read these pages for some reference:

1. git-diff docs
2. git-check-ref-format docs
3. Dealing with special characters in branch and tag names

You can see the rules for valid git branch or tag name in [2] and additional restriction from Github in [3].

[wooorm]

Much of these docs are about Git instead of GitHub. In my experience of reverse-engineering how GH works, it’s often weird and different. So I do think it is wise to try with a test repo and try different weird characters in branch and tag names, and to different min and max sizes.
Are you interested in working on this?