tests(extgen): add integration tests (#1984)

Fix #1975

.github/workflows/tests.yaml

@@ -93,6 +93,49 @@ jobs:
         if: matrix.php-versions == '8.5'
         run: go mod tidy -diff
         working-directory: caddy/
+  integration-tests:
+    name: Integration Tests (Linux, PHP ${{ matrix.php-versions }})
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        php-versions: ["8.3", "8.4", "8.5"]
+    steps:
+      - uses: actions/checkout@v5
+        with:
+          persist-credentials: false
+      - uses: actions/setup-go@v6
+        with:
+          go-version: "1.25"
+          cache-dependency-path: |
+            go.sum
+            caddy/go.sum
+      - uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php-versions }}
+          ini-file: development
+          coverage: none
+          tools: none
+        env:
+          phpts: ts
+          debug: true
+      - name: Install PHP development libraries
+        run: sudo apt-get update && sudo apt-get install -y libkrb5-dev libsodium-dev libargon2-dev
+      - name: Install xcaddy
+        run: go install github.com/caddyserver/xcaddy/cmd/xcaddy@latest
+      - name: Download PHP sources
+        run: |
+          PHP_VERSION=$(php -r "echo PHP_VERSION;")
+          wget -q "https://www.php.net/distributions/php-${PHP_VERSION}.tar.gz"
+          tar xzf "php-${PHP_VERSION}.tar.gz"
+          echo "GEN_STUB_SCRIPT=${PWD}/php-${PHP_VERSION}/build/gen_stub.php" >> "${GITHUB_ENV}"
+      - name: Set CGO flags
+        run: |
+          echo "CGO_CFLAGS=$(php-config --includes)" >> "${GITHUB_ENV}"
+          echo "CGO_LDFLAGS=$(php-config --ldflags) $(php-config --libs)" >> "${GITHUB_ENV}"
+      - name: Run integration tests
+        working-directory: internal/extgen/
+        run: go test -tags integration -v -timeout 30m
   tests-mac:
     name: Tests (macOS, PHP 8.5)
     runs-on: macos-latest
@@ -106,7 +149,7 @@ jobs:
         with:
           go-version: "1.25"
           cache-dependency-path: |
-            go.sum 
+            go.sum
             caddy/go.sum
       - uses: shivammathur/setup-php@v2
         with: