Add basic test and workflow for PRs (#8)

.github/workflows/check-format.yml

@@ -15,7 +15,7 @@ jobs:
       - name: Set up Node.js
         uses: actions/setup-node@v2
         with:
-          node-version: '14'
+          node-version: '20'
 
       - name: Install dependencies
         run: npm install

.github/workflows/check-tests.yml

@@ -0,0 +1,24 @@
+name: Check tests
+
+on:
+  pull_request:
+    types: [opened, synchronize]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v2
+        with:
+          node-version: '20'
+
+      - name: Install dependencies
+        run: npm install
+
+      - name: Run tests
+        run: npm test