chore: introduce Testing Apps + CI workflow

.github/workflows/apps.yml

@@ -0,0 +1,40 @@
+name: Testing apps
+on: [push, pull_request]
+
+jobs:
+  testing_app:
+    strategy:
+      fail-fast: false
+      matrix:
+        test_app:
+          - name: pnpm
+            working_directory: test_apps/pnpm
+            script: |
+              pnpm install --frozen-lockfile
+              pnpm run dev
+              pnpm run build
+
+    name: Testing app (${{ matrix.test_app.name }})
+    runs-on: ubuntu-latest
+
+    steps:
+      -   name: Checkout
+          uses: actions/checkout@v2.0.0
+
+      -   name: Node ${{matrix.node-versions}}
+          uses: actions/setup-node@v2
+          with:
+            node-version: '14'
+
+      -   if: matrix.test_app.name == 'pnpm'
+          name: Install pnpm
+          uses: pnpm/action-setup@v2
+          with:
+            version: latest
+
+      -   name: Install Yarn Dependencies
+          run: yarn install
+
+      -   name: Running script
+          working-directory: ${{ matrix.test_app.working_directory }}
+          run: ${{ matrix.test_app.script }}

test_apps/pnpm/assets/app.js

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+/*
+ * This file is part of the Symfony Webpack Encore package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+'use strict';
+
+console.log('Hello world!');

test_apps/pnpm/package.json

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+{
+  "license": "UNLICENSED",
+  "private": true,
+  "scripts": {
+    "dev-server": "encore dev-server",
+    "dev": "encore dev",
+    "watch": "encore dev --watch",
+    "build": "encore production --progress"
+  },
+  "devDependencies": {
+    "@symfony/webpack-encore": "link:../..",
+    "webpack": "^5.74.0"
+  }
+}