feat: add jest tests to validation

.github/workflows/validate-pr.yml

@@ -6,10 +6,6 @@ on:
       - develop
       - main
 
-env:
-  NODE_OPTIONS: '--max-old-space-size=4096'
-  CHOKIDAR_USEPOLLING: 1
-
 jobs:
   build:
     name: Gatsby Build
@@ -50,6 +46,32 @@ jobs:
           GATSBY_EXPERIMENTAL_PAGE_BUILD_ON_DATA_CHANGES: true
           CI: true
 
+  test:
+    name: Run Tests
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v2
+        with:
+          node-version: 12
+
+      - name: Cache dependencies
+        id: yarn-cache
+        uses: actions/cache@v2
+        with:
+          path: '**/node_modules'
+          key: ${{ runner.os }}-node-modules-${{ hashFiles('**/yarn.lock') }}
+
+      - name: Install dependencies
+        if: steps.yarn-cache.outputs.cache-hit != 'true'
+        run: yarn install --frozen-lockfile
+
+      - name: Jest test
+        run: yarn test --passWithNoTests
+
   lint:
     name: Run Eslint
     runs-on: ubuntu-latest