chore: add commit lint action (#8)

This adds an action for linting commit messages. Following the
conventional commit rule helps to automatically generate changelogs in
the future.

Signed-off-by: Daeyeon Jeong <[email protected]>

.github/workflows/commit_lint.yml

@@ -0,0 +1,32 @@
+name: Lint commit message
+
+on: [pull_request]
+
+env:
+  NODE_VERSION: lts/*
+
+jobs:
+  lint-commit-message:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Compute number of commits
+        id: nb-of-commits
+        run: |
+          echo "plusOne=$((${{ github.event.pull_request.commits }} + 1))" >> $GITHUB_OUTPUT
+          echo "minusOne=$((${{ github.event.pull_request.commits }} - 1))" >> $GITHUB_OUTPUT
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: ${{ steps.nb-of-commits.outputs.plusOne }}
+          persist-credentials: false
+      - run: git reset HEAD^2
+      - name: Install Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: ${{ env.NODE_VERSION }}
+      - name: Install required dependencies
+        run: |
+          npm install -g @commitlint/cli @commitlint/config-conventional
+      - name: Validate the first commit message
+        run: |
+          commitlint -V --config .github/workflows/commitlint.config.js \
+            --to HEAD~${{ steps.nb-of-commits.outputs.minusOne }}

.github/workflows/commitlint.config.js

@@ -0,0 +1,20 @@
+module.exports = {
+  extends: ["@commitlint/config-conventional"],
+  rules: {
+    "header-max-length": () => [2, "always", 72],
+    "type-enum": () => [
+      2,
+      "always",
+      ["feat", "fix", "refactor", "chore", "test", "doc", "release", "revert"],
+    ],
+    "scope-enum": [
+      2,
+      "always",
+      ["core", "database", "functions", "storage", "test"],
+    ],
+    "body-max-line-length": [0, "always"],
+    "footer-max-line-length": [0, "always"],
+  },
+  helpUrl:
+    "https://github.com/flutter-tizen/flutterfire/blob/main/CONTRIBUTING.md",
+};