Add callable unit testing

.github/workflows/callable.tests.yml

@@ -0,0 +1,30 @@
+name: Run tests
+
+on:
+  workflow_call:
+
+permissions:
+  contents: read
+
+jobs:
+  run_tests:
+    runs-on: ubuntu-latest
+    strategy:
+        matrix:
+          node-version: [14.x, 16.x, 18.x] 
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v2
+        with:
+          node-version: ${{ matrix.node-version }}
+          cache: 'npm' 
+
+      - name: Install Node.js dependencies
+        run: npm ci 
+
+      - name: Run tests
+        run: npm test