Use compulsory PHPUnit Polyfills package for testing

.github/workflows/tests.yml

@@ -43,6 +43,7 @@ jobs:
       uses: shivammathur/setup-php@v2
       with:
         php-version: ${{ matrix.php }}
+        tools: phpunit-polyfills
 
     - name: Install WordPress
       run: |
@@ -51,6 +52,7 @@ jobs:
         cd "$WP_DEVELOP_DIR"
         # set up tests config
         mv wp-tests-config-sample.php wp-tests-config.php
+        sed -i "s/localhost/127.0.0.1/" wp-tests-config.php
         sed -i "s/youremptytestdbnamehere/wordpress_test/" wp-tests-config.php
         sed -i "s/yourusernamehere/root/" wp-tests-config.php
         sed -i "s/yourpasswordhere/root/" wp-tests-config.php
@@ -82,6 +84,7 @@ jobs:
         composer install --prefer-dist --no-progress
         composer bin build install
         composer compose
+        composer dump-autoload --dev
 
     - name: Check PHP code
       run: composer check-code

composer.json

@@ -42,7 +42,8 @@
     "spatie/invade": "^2.0",
     "bamarni/composer-bin-plugin": "^1.8",
     "guzzlehttp/guzzle": "^7.8",
-    "league/html-to-markdown": "^5.1"
+    "league/html-to-markdown": "^5.1",
+    "yoast/phpunit-polyfills": "^2.0"
   },
   "autoload": {
     "classmap": [