Add comprehensive unit and integration testing infrastructure with PHPUnit and WordPress filter system

.github/workflows/releases.yml

@@ -3,7 +3,7 @@ name: Create Release
 on:
   push:
     tags:
-      - 'v*' # Push events to matching v*, i.e. v1.0, v20.15.10
+      - 'v*' # Push events matching v*, i.e. v1.0, v20.15.10
 
 jobs:
   release:

.github/workflows/tests.yml

@@ -0,0 +1,62 @@
+name: Tests
+
+on:
+  push:
+    branches:
+      - "*"
+  pull_request:
+    branches:
+      - "*"
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    name: Run PHPUnit Tests
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        php-version: ['8.0', '8.1', '8.2', '8.3']
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php-version }}
+          extensions: json, zip, dom
+          coverage: xdebug
+
+      - name: Validate composer.json
+        run: composer validate --strict --no-check-version
+
+      - name: Cache Composer packages
+        id: composer-cache
+        uses: actions/cache@v3
+        with:
+          path: vendor
+          key: ${{ runner.os }}-php-${{ matrix.php-version }}-${{ hashFiles('**/composer.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-php-${{ matrix.php-version }}-
+
+      - name: Install dependencies
+        run: composer update --prefer-dist --no-progress  # use update to allow for different php versions in matrix.
+
+
+      - name: Run test suite
+        run: composer test
+
+      - name: Generate coverage report (PHP 8.3 only)
+        if: matrix.php-version == '8.3'
+        run: ./vendor/bin/phpunit --coverage-clover coverage.xml
+
+      - name: Upload coverage to artifact (PHP 8.3 only)
+        if: matrix.php-version == '8.3'
+        uses: actions/upload-artifact@v4
+        with:
+          name: coverage-report
+          path: coverage.xml

.gitignore

@@ -26,3 +26,8 @@ node_modules
 
 /build/
 /touchpoint-wp.zip
+
+# Test artifacts
+/.phpunit.cache/
+/coverage/
+.phpunit.result.cache