adding step for creating the test components

Author: BSd3v

.github/workflows/testing.yml

@@ -261,6 +261,9 @@ jobs:
           touch __init__.py
           pytest --headless --nopercyfinalize tests/background_callback -v -s
 
+      - name: Build/Setup test components
+        run: npm run setup-tests.py
+
       - name: Run Async Callback Tests
         run: |
           find packages -name dash-*.whl -print -exec sh -c 'pip install "{}[async]"' \;