Add GitHub Actions workflow for standalone PHP unit tests

Add a CI workflow running standalone PHP tests (no WordPress or database
dependency) on PHP 8.4 with PHPUnit 11 and Yoast PHPUnit Polyfills v4.

Test suites: Serve Happy API, Browse Happy API, Slack Trac Bot, and
Slack Props Library.

- Remove redundant class_alias from Serve Happy bootstrap (PHPUnit 11
  provides PHPUnit_Framework_TestCase internally)
- Fix Browse Happy test: IE is always flagged as needing an upgrade
- Use --no-configuration to bypass legacy phpunit.xml attributes

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: dd32

.github/workflows/unit-tests.yml

@@ -0,0 +1,71 @@
+name: Unit Tests
+
+on:
+  push:
+    branches: [ trunk ]
+  pull_request:
+    branches: [ trunk ]
+
+jobs:
+  # Standalone PHP tests — no WordPress or database dependency.
+  php-standalone:
+    name: "PHP: ${{ matrix.name }}"
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - name: Serve Happy API
+            working-directory: api.wordpress.org/public_html/core/serve-happy/1.0
+            phpunit-args: "--no-configuration --exclude-group serve-happy-live-http --bootstrap /tmp/bootstrap-serve-happy.php tests/"
+          - name: Browse Happy API
+            working-directory: api.wordpress.org/public_html/core/browse-happy/1.0
+            phpunit-args: "--no-configuration --bootstrap /tmp/bootstrap-polyfills.php tests/phpunit/tests/"
+          - name: Slack Trac Bot
+            working-directory: common/includes/tests/slack/trac
+            phpunit-args: "--bootstrap /tmp/bootstrap-polyfills.php bot.php"
+          - name: Slack Props Library
+            working-directory: common/includes/slack/props/tests
+            phpunit-args: "--bootstrap /tmp/bootstrap-wpdb-stub.php ."
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: "8.4"
+          tools: phpunit:^11
+
+      - name: Install PHPUnit Polyfills
+        run: |
+          mkdir -p /tmp/polyfills
+          composer require --working-dir=/tmp/polyfills yoast/phpunit-polyfills:^4.0 --no-interaction
+
+      - name: Create CI bootstraps
+        run: |
+          # Base bootstrap: polyfills only
+          cat > /tmp/bootstrap-polyfills.php << 'PHPEOF'
+          <?php
+          require_once '/tmp/polyfills/vendor/autoload.php';
+          PHPEOF
+
+          # Serve Happy bootstrap: polyfills + project bootstrap
+          cat > /tmp/bootstrap-serve-happy.php << PHPEOF
+          <?php
+          require_once '/tmp/polyfills/vendor/autoload.php';
+          require_once '${{ github.workspace }}/${{ matrix.working-directory }}/tests/bootstrap.php';
+          PHPEOF
+
+          # wpdb stub bootstrap: polyfills + stub class
+          cat > /tmp/bootstrap-wpdb-stub.php << 'PHPEOF'
+          <?php
+          require_once '/tmp/polyfills/vendor/autoload.php';
+          class wpdbStub {
+              public function prepare( $query, ...$args ) { return $query; }
+              public function get_results( $query, $output = 'OBJECT' ) { return []; }
+          }
+          PHPEOF
+
+      - name: Run PHPUnit
+        working-directory: ${{ matrix.working-directory }}
+        run: phpunit ${{ matrix.phpunit-args }}

api.wordpress.org/public_html/core/browse-happy/1.0/tests/phpunit/tests/browse-happy.php

@@ -853,6 +853,12 @@ function test_upgrade_browsers( $header ) {
 			return;
 		}
 
+		// Internet Explorer is always flagged as needing an upgrade.
+		if ( 'Internet Explorer' === $parsed['name'] ) {
+			$this->assertTrue( $parsed['upgrade'] );
+			return;
+		}
+
 		$versions = get_browser_current_versions();
 
 		if ( ! empty( $versions[ $parsed['name'] ] ) ) {

api.wordpress.org/public_html/core/serve-happy/1.0/tests/bootstrap.php

@@ -5,11 +5,6 @@
 	xdebug_disable();
 }
 
-// PHP 6+ Compatibility.
-if ( class_exists( '\PHPUnit\Runner\Version' ) && version_compare( \PHPUnit\Runner\Version::id(), '6.0', '>=' ) ) {
-	class_alias( '\PHPUnit\Framework\TestCase', 'PHPUnit_Framework_TestCase' );
-}
-
 // Error Output handler for the API.
 function bail( $code, $message, $status = 400, $http_code_text = '' ) {
 	return compact( 'code', 'message', 'status' );