ci: add ci test

.github/workflows/test.yml

@@ -0,0 +1,20 @@
+name: Test
+
+on: [push]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [14, 15]
+    steps:
+      - uses: actions/checkout@v1
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v1
+        with:
+          node-version: ${{ matrix.node-version }}
+      - name: install and test
+        run: |
+          yarn install
+          yarn test

README.md

@@ -1,5 +1,6 @@
 # (WIP) VitePress 📝💨
 
+[![Test](https://github.com/vuejs/vitepress/workflows/Unit%20Test/badge.svg)](https://github.com/vuejs/vitepress/actions)
 [![npm](https://img.shields.io/npm/v/vitepress)](https://www.npmjs.com/package/vitepress)
 
 ---