Add testing on CI

.github/workflows/automated_testing.yml

@@ -0,0 +1,48 @@
+name: Automated Testing
+
+on:
+  push:
+
+permissions:
+  contents: read
+
+jobs:
+  composer:
+    name: Validate composer files
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: shivammathur/setup-php@v2
+        with:
+          php-version: 8.2
+
+      - uses: actions/checkout@v4
+
+      - name: Validate composer.json and composer.lock
+        run: composer validate --strict
+
+  phpunit:
+    name: 'Tests: Unit'
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: shivammathur/setup-php@v2
+        with:
+          php-version: 8.2
+
+      - uses: actions/checkout@v4
+
+      - name: Cache Composer packages
+        id: composer-cache
+        uses: actions/cache@v4
+        with:
+          path: vendor
+          key: "${{ runner.os }}-php-${{ hashFiles('**/composer.lock') }}"
+          restore-keys: |
+            ${{ runner.os }}-php-
+
+      - name: Install dependencies
+        uses: ramsey/composer-install@v3
+
+      - name: 'Run all PHPUnit tests'
+        run: composer run phpunit