only lint the files that changed (#22924)

* only lint the files that changed

* allowed action

* do nothing

* debug more

* less debugging

* debug

* debug

* debug

* using patterns

* testing something

* testing something (2)

* lemme try something

* lemme try something

* one more attempt

* testing

* tidying up

* sample changes

* add debugging

* some code comments

* fine but sample changes

* update allowed actions

* final cleaning before opening PR for review

* tiny update

* remove commented out code

* feedbacked

Author: Peter Bengtsson

.github/allowed-actions.js

@@ -18,6 +18,7 @@ export default [
   'dawidd6/action-download-artifact@af92a8455a59214b7b932932f2662fdefbd78126', // v2.15.0
   'docker://chinthakagodawita/autoupdate-action:v1',
   'dorny/paths-filter@eb75a1edc117d3756a18ef89958ee59f9500ba58',
+  'trilom/file-changes-action@a6ca26c14274c33b15e6499323aac178af06ad4b', // v1.2.4
   'github/codeql-action/analyze@v1',
   'github/codeql-action/init@v1',
   'juliangruber/approve-pull-request-action@c530832d4d346c597332e20e03605aa94fa150a8',

.github/workflows/test.yml

@@ -46,6 +46,18 @@ jobs:
           # Enables cloning the Early Access repo later with the relevant PAT
           persist-credentials: 'false'
 
+      - name: Gather files changed
+        uses: trilom/file-changes-action@a6ca26c14274c33b15e6499323aac178af06ad4b
+        id: get_diff_files
+        with:
+          # So that `steps.get_diff_files.outputs.files` becomes
+          # a string like `foo.js path/bar.md`
+          output: ' '
+
+      - name: Insight into changed files
+        run: |
+          echo ${{ steps.get_diff_files.outputs.files }}
+
       - name: Setup node
         uses: actions/setup-node@270253e841af726300e85d718a5f606959b2903c
         with:
@@ -67,4 +79,6 @@ jobs:
         run: npm run build
 
       - name: Run tests
+        env:
+          DIFF_FILES: ${{ steps.get_diff_files.outputs.files }}
         run: npm run test tests/${{ matrix.test-group }}/

tests/linting/lint-files.js

@@ -356,6 +356,63 @@ function getContent(content) {
   return null
 }
 
+// Filter out entries from an array like this:
+//
+//    [
+//      [relativePath, absolutePath],
+//      ...
+// so it's only the files mentioned in the DIFF_FILES environment
+// variable, but only if it's set and present.
+
+// Setting an environment varible called `DIFF_FILES` is optional.
+// But if and only if it's set, we will respect it.
+// And if it set, turn it into a cleaned up Set so it's made available
+// every time we use it.
+if (process.env.DIFF_FILES) {
+  // Parse and turn that environment variable string into a set.
+  // It's faster to do this once and then re-use over and over in the
+  // .filter() later on.
+  const only = new Set(
+    // If the environment variable encodes all the names
+    // with quotation marks, strip them.
+    // E.g. Turn `"foo" "bar"` into ['foo', 'bar']
+    // Note, this assumes no possible file contains a space.
+    process.env.DIFF_FILES.split(/\s+/g).map((name) => {
+      if (/^['"]/.test(name) && /['"]$/.test(name)) {
+        return name.slice(1, -1)
+      }
+      return name
+    })
+  )
+  const filterFiles = (tuples) =>
+    tuples.filter(
+      ([relativePath, absolutePath]) => only.has(relativePath) || only.has(absolutePath)
+    )
+  mdToLint = filterFiles(mdToLint)
+  ymlToLint = filterFiles(ymlToLint)
+  ghesReleaseNotesToLint = filterFiles(ghesReleaseNotesToLint)
+  ghaeReleaseNotesToLint = filterFiles(ghaeReleaseNotesToLint)
+  learningTracksToLint = filterFiles(learningTracksToLint)
+  featureVersionsToLint = filterFiles(featureVersionsToLint)
+}
+
+if (
+  mdToLint.length +
+    ymlToLint.length +
+    ghesReleaseNotesToLint.length +
+    ghaeReleaseNotesToLint.length +
+    learningTracksToLint.length +
+    featureVersionsToLint.length <
+  1
+) {
+  // With this in place, at least one `test()` is called and you don't
+  // get the `Your test suite must contain at least one test.` error
+  // from `jest`.
+  describe('deliberately do nothing', () => {
+    test('void', () => {})
+  })
+}
+
 describe('lint markdown content', () => {
   if (mdToLint.length < 1) return
   describe.each(mdToLint)('%s', (markdownRelPath, markdownAbsPath) => {