Ignore links to other branches

lib/find/config.js

@@ -46,7 +46,12 @@ export function config(ctx) {
 
     if (info && info.type !== 'gist') {
       if (info.type in viewPaths) {
-        urlConfig.prefix = '/' + info.path() + '/' + viewPaths[info.type] + '/'
+        urlConfig.prefix =
+          new URL(info.browse({treepath: viewPaths[info.type]})).pathname + '/'
+        // GitHost#browse() omits the "blob" segment from branch-less URLs.
+        if (!info.committish) {
+          urlConfig.prefix += viewPaths[info.type] + '/'
+        }
       }
 
       if (info.type in headingPrefixes) {

lib/find/find-references.js

@@ -248,11 +248,16 @@ function urlToPath(value, config, type) {
 
     value = url.pathname.slice(config.urlConfig.prefix.length)
 
+    // Drop the first path segment (the branch) if the prefix is branch-less (matches every branch).
+    // Make an educated guess whether the prefix is branch-less: Currently every hosted-git-info browsetemplate/pathtemplate has <= 2 segments (`${user}/${project}`), plus e.g. "blob" and surrounding slashes -> 5.
+    //
     // Things get interesting here: branches: `foo/bar/baz` could be `baz` on
     // the `foo/bar` branch, or, `baz` in the `bar` directory on the `foo`
     // branch.
     // Currently, we’re ignoring this and just not supporting branches.
-    value = value.split(slash).slice(1).join(slash)
+    if (config.urlConfig.prefix.split('/').length <= 5) {
+      value = value.split(slash).slice(1).join(slash)
+    }
 
     return normalize(
       path.resolve(config.root, value + (type === 'image' ? '' : url.hash)),

lib/index.js

@@ -25,9 +25,11 @@
  *   URL to hosted Git.
  *   If `repository` is nullish, the Git origin remote is detected.
  *   If the repository resolves to something npm understands as a Git host such
- *   as GitHub, GitLab, or Bitbucket, full URLs to that host (say,
- *   `https://github.com/remarkjs/remark-validate-links/readme.md#install`) can
+ *   as GitHub, GitLab, or Bitbucket, then full URLs to that host (say,
+ *   <https://github.com/remarkjs/remark-validate-links/blob/main/readme.md#install>) can
  *   also be checked.
+ *   If it resolves to a branch (e.g. <https://github.com/remarkjs/remark-validate-links.git#main>) then links to other branches are ignored --- otherwise the plugin checks links to all branches as if they pointed to the current branch.
+ *   When the repository is automatically detected the plugin checks links to all branches.
  *   If you’re not in a Git repository, you must pass `repository: false`
  *   explicitly.
  * @property {string} [root]

package.json

@@ -80,7 +80,7 @@
   "scripts": {
     "build": "rimraf \"lib/**/*.d.ts\" \"test/**/*.d.ts\" \"*.d.ts\" && tsc && type-coverage",
     "format": "remark . -qfo --ignore-pattern test/ && prettier . -w --loglevel warn && xo --fix",
-    "test-api": "node --conditions development test/index.js",
+    "test-api": "tape test/index.js test/other-branches.js",
     "test-coverage": "c8 --check-coverage --branches 100 --functions 100 --lines 100 --statements 100 --reporter lcov npm run test-api",
     "test": "npm run build && npm run format && npm run test-coverage"
   },

readme.md

@@ -164,8 +164,15 @@ URL to hosted Git (`string?` or `false`).
 If `repository` is nullish, the Git origin remote is detected.
 If the repository resolves to something [npm understands][package-repository] as
 a Git host such as GitHub, GitLab, or Bitbucket, then full URLs to that host
-(say, `https://github.com/remarkjs/remark-validate-links/readme.md#install`) can
-also be checked.
+(say,
+<https://github.com/remarkjs/remark-validate-links/blob/main/readme.md#install>)
+can also be checked.
+If it resolves to a branch (e.g.
+<https://github.com/remarkjs/remark-validate-links.git#main>) then links to
+other branches are ignored --- otherwise the plugin checks links to all branches
+as if they pointed to the current branch.
+When the repository is automatically detected the plugin checks links to all
+branches.
 If you’re not in a Git repository, you must pass `repository: false`
 explicitly.
 

test/other-branches.js

@@ -0,0 +1,93 @@
+import {remark} from 'remark'
+import test from 'tape'
+import {engine as engineCb} from 'unified-engine'
+import {promisify} from 'node:util'
+import {VFile} from 'vfile'
+import remarkValidateLinks from '../index.js'
+
+const engine = promisify(engineCb)
+
+// Should ignore links to other branches.
+const options = {repository: 'https://github.com/wooorm/test.git#main'}
+
+test('same branch, working link', async (t) => {
+  t.deepEqual(
+    await process(
+      '[](https://github.com/wooorm/test/blob/main/examples/github.md#hello)'
+    ),
+    [],
+    'nothing to report'
+  )
+})
+
+test('other branch, working link', async (t) => {
+  t.deepEqual(
+    await process(
+      '[](https://github.com/wooorm/test/blob/foo-bar/examples/github.md#hello)'
+    ),
+    [],
+    'nothing to ignore'
+  )
+})
+
+test('same branch, no such heading', async (t) => {
+  t.deepEqual(
+    await process(
+      '[](https://github.com/wooorm/test/blob/main/examples/github.md#world)'
+    ),
+    [
+      'input.md:1:1-1:70: Link to unknown heading in `examples/github.md`: `world`'
+    ],
+    'should be reported'
+  )
+})
+
+test('other branch, no such heading', async (t) => {
+  t.deepEqual(
+    await process(
+      '[](https://github.com/wooorm/test/blob/foo-bar/examples/github.md#world)'
+    ),
+    [],
+    'should be ignored'
+  )
+})
+
+test('same branch, no such file', async (t) => {
+  t.deepEqual(
+    await process(
+      '[](https://github.com/wooorm/test/blob/main/examples/world.md#hello)'
+    ),
+    [
+      'input.md:1:1-1:69: Link to unknown file: `examples/world.md`',
+      'input.md:1:1-1:69: Link to unknown heading in `examples/world.md`: `hello`'
+    ],
+    'should be reported'
+  )
+})
+
+test('other branch, no such file', async (t) => {
+  t.deepEqual(
+    await process(
+      '[](https://github.com/wooorm/test/blob/foo-bar/examples/world.md#hello)'
+    ),
+    [],
+    'should be ignored'
+  )
+})
+
+/**
+ * Run the plugin on a markdown test case and return a list of stringified messages.
+ * unified-engine is needed to cross-reference links between files, by creating a FileSet.
+ *
+ * @param {string} value
+ */
+async function process(value) {
+  const file = new VFile({value, path: 'input.md'})
+  await engine({
+    processor: remark,
+    files: [file],
+    plugins: [[remarkValidateLinks, options]],
+    silent: true
+  })
+  return file.messages.map((message) => String(message))
+}