Add CI

Author: code-asher

.github/workflows/ci.yaml

@@ -0,0 +1,37 @@
+name: ci
+
+on:
+  push:
+    branches: "**"
+    tags-ignore: "v*"
+  pull_request:
+
+jobs:
+  prebuild:
+    name: Pre-build checks
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@v2
+
+      - name: Install Node.js v12
+        uses: actions/setup-node@v2
+        with:
+          node-version: "12"
+
+      - name: Fetch dependencies from cache
+        id: cache-yarn
+        uses: actions/cache@v2
+        with:
+          path: "**/node_modules"
+          key: yarn-build-${{ hashFiles('**/yarn.lock') }}
+
+      - name: Install dependencies
+        if: steps.cache-yarn.outputs.cache-hit != 'true'
+        run: yarn --frozen-lockfile
+
+      - name: Run yarn lint
+        run: yarn lint
+
+      - name: Run yarn test
+        run: yarn test