create test action

.github/workflows/test.yml

@@ -0,0 +1,15 @@
+name: test
+on:
+  push:
+    branches-ignore: [main]
+jobs:
+  main:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-node@v2
+        with: { node-version: lts/*, cache: yarn }
+      - name: Build
+        run: |
+          yarn install
+          yarn build