Migrate linter workflow to GitHub Actions

This runs faster and allows for future improvements.

I'm following a general principle of keeping code that isn't portable
between CI providers inside the config file for the CI provider. So in
this case we remove the Circle-CI-specific stuff from the file in
tools/scripts/, and into .github/workflows/. We use an external action
(tj-actions/changed-files) to gather the list of files to lint.

.circleci/config.yml

@@ -37,7 +37,7 @@ execution_steps: &execution_steps
     - run: hostPath=$HOME/.esvu/bin/$hostPath npm run ci
 
 jobs:
-  "Test262: verify tools; build & lint tests":
+  "Test262: verify tools; build tests":
     docker:
       - image: cimg/python:3.7.4
     working_directory: ~/test262
@@ -46,21 +46,12 @@ jobs:
       - run:
           name: "Install requirements for generation tool"
           command: python -m pip install --user --requirement tools/generation/requirements.txt
-      - run:
-          name: "Install requirements for lint tool"
-          command: python -m pip install --user --requirement tools/lint/requirements.txt
       - run:
           name: "Test the generation tool"
           command: ./tools/generation/test/run.py
-      - run:
-          name: "Test the lint tool"
-          command: ./tools/lint/test/run.py
       - run:
           name: "Build tests; check for new changes"
           command: ./tools/scripts/ci_build.sh
-      - run:
-          name: "Lint tests"
-          command: ./tools/scripts/ci_lint.sh
   "V8: New or modified tests execution":
     docker:
       - image: *node_image
@@ -134,7 +125,7 @@ workflows:
   version: 2
   Tools:
     jobs:
-      - "Test262: verify tools; build & lint tests"
+      - "Test262: verify tools; build tests"
   Tests execution:
     jobs:
       # - "ChakraCore: New or modified tests execution"

.github/workflows/checks-main.yml

@@ -0,0 +1,28 @@
+name: Checks
+
+on: push
+
+jobs:
+  lint:
+    name: Lint tests
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.x'
+          cache: pip
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install -r tools/lint/requirements.txt
+
+      - name: Test the lint tool
+        run: ./tools/lint/test/run.py
+
+      - name: Lint all tests
+        run: ./tools/scripts/ci_lint.sh

.github/workflows/checks-pr.yml

@@ -0,0 +1,42 @@
+name: Required PR checks
+
+on: pull_request
+
+jobs:
+  lint:
+    name: Lint
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.x'
+          cache: pip
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install -r tools/lint/requirements.txt
+
+      - name: Test the lint tool
+        run: ./tools/lint/test/run.py
+
+      - name: Identify new or changed tests
+        id: changed_tests
+        uses: tj-actions/changed-files@v45
+        with:
+          files: test/
+
+      - name: Lint new or changed tests
+        if: steps.changed_tests.outputs.any_changed == 'true'
+        env:
+          CHANGED: ${{ steps.changed_tests.outputs.all_changed_files }}
+        run: |
+          echo New or modified test files:
+          for file in $CHANGED; do
+            echo $file
+          done
+          ./tools/scripts/ci_lint.sh $CHANGED

tools/scripts/ci_lint.sh

@@ -1,18 +1,7 @@
 #!/bin/bash
 
-if [ "$CIRCLE_PULL_REQUEST" != "" ]; then
-  paths=$(git diff --diff-filter ACMR --name-only origin/main.. -- test/)
-
-  if [ "$paths" == "" ]; then
-    echo No test files added or modified. Exiting.
-    exit 0
-  fi
-
-  echo New or modified test files:
-  echo "$paths"
-
-else
-  paths="test/"
+if [ "$#" -eq 0 ]; then
+  set -- test/
 fi
 
-./tools/lint/lint.py --exceptions lint.exceptions $paths
+./tools/lint/lint.py --exceptions lint.exceptions $@