Add WP PHPUnit integration tests

.github/workflows/integration-tests.yml

@@ -0,0 +1,39 @@
+name: Integration Tests
+
+on:
+  # Run on all pull requests.
+  pull_request:
+  push:
+    branches:
+      - trunk
+
+# Cancels all previous workflow runs for pull requests that have not completed.
+concurrency:
+  # The concurrency group contains the workflow name and the branch name for pull requests
+  # or the commit hash for any other events.
+  group: ${{ github.workflow }}-${{ github.event_name == 'pull_request' && github.head_ref || github.sha }}
+  cancel-in-progress: true
+
+jobs:
+  test:
+    name: WordPress Integration Tests
+    runs-on: ubuntu-24.04
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Use desired version of NodeJS
+        uses: actions/[email protected]
+        with:
+          node-version: 20
+          cache: npm
+
+      - name: Npm install
+        run: npm ci
+
+      - name: Start up WordPress environment
+        run: npm run dev:build
+
+      - name: Run Integration tests
+        run: npm run test:integration

.gitignore

@@ -41,6 +41,7 @@ vendor/
 
 # PHPUnit
 .phpunit.cache/
+.phpunit.result.cache
 
 # Editors
 .idea/*

composer.json

@@ -38,12 +38,15 @@
   "require-dev": {
     "automattic/vipwpcs": "^3.0",
     "phpcompatibility/phpcompatibility-wp": "^2.1",
-    "phpunit/phpunit": "^10",
+    "phpunit/phpunit": "^9",
     "slevomat/coding-standard": "^8.15",
     "php-stubs/wordpress-stubs": "^6.6",
     "psalm/phar": "^5.26",
     "mockery/mockery": "^1.6",
-    "php-stubs/wordpress-globals": "^0.2.0"
+    "wp-phpunit/wp-phpunit": "^6.7",
+    "yoast/phpunit-polyfills": "^2.0",
+    "php-stubs/wordpress-globals": "^0.2.0",
+    "php-stubs/wordpress-tests-stubs": "^6.7"
   },
   "config": {
     "allow-plugins": {