Add CI artifacts.

Author: StevenXL

.github/workflows/ci.yml

@@ -0,0 +1,19 @@
+name: CI
+
+on:
+  pull_request:
+  push:
+    branches: main
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-node@v2
+        with:
+          cache: yarn
+      - run: yarn install
+      - run: yarn build
+      - run: yarn test
+      - run: yarn run check-git-clean

check-git-clean.sh

@@ -0,0 +1,13 @@
+#!/bin/bash -e
+
+if ! git diff --quiet; then echo "
+
+The CI build resulted in additional changed files.
+Typically this is due to not running yarn build locally before
+submitting a pull request.
+
+The following changes were found:
+";
+
+  git diff --exit-code;
+fi;

package.json

@@ -7,7 +7,8 @@
     "build": "babel src -o dist/index.js",
     "dev": "watch 'yarn run build' src",
     "test": "jest",
-    "test:watch": "yarn run test -- --watch"
+    "test:watch": "yarn run test -- --watch",
+    "check-git-clean": "./check-git-clean.sh"
   },
   "babel": {
     "presets": [