ci: Add unit testing workflow and update .gitattributes

Author: roxblnfk

.gitattributes

@@ -12,3 +12,4 @@ Dockerfile             export-ignore
 infection.*            export-ignore
 tests                  export-ignore
 docs                   export-ignore
+resources              export-ignore

.github/workflows/testing.yml

@@ -0,0 +1,107 @@
+---
+
+name: 🧪 Unit testing
+
+on:  # yamllint disable-line rule:truthy
+  pull_request:
+    branches:
+      - 1.x
+  push:
+    branches:
+      - 1.x
+
+jobs:
+  code-coverage:
+    timeout-minutes: 4
+    runs-on: ${{ matrix.os }}
+    concurrency:
+      cancel-in-progress: true
+      group: code-coverage-${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}-${{ matrix.php-version }}-${{ matrix.dependencies }}
+    strategy:
+      fail-fast: true
+      matrix:
+        os:
+          - ubuntu-latest
+        php-version:
+          - '8.2'
+        dependencies:
+          - locked
+    steps:
+      - name: 📦 Check out the codebase
+        uses: actions/checkout@v5
+
+      - name: 🛠️ Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php-version }}
+          ini-values: error_reporting=E_ALL
+          coverage: xdebug
+
+      - name: 🛠️ Setup problem matchers
+        run: |
+          echo "::add-matcher::${{ runner.tool_cache }}/php.json"
+          echo "::add-matcher::${{ runner.tool_cache }}/phpunit.json"
+
+      - name: 🤖 Validate composer.json and composer.lock
+        run: composer validate --ansi --strict
+
+      - name: 📥 Install dependencies with composer
+        uses: ramsey/composer-install@v3
+        with:
+          dependency-versions: ${{ matrix.dependencies }}
+
+      - name: 🧪 Collect code coverage with Xdebug and PhpUnit
+        run: composer test:cc
+
+      - name: 📤 Upload code coverage report to Codecov
+        uses: codecov/codecov-action@v4
+        with:
+          files: runtime/phpunit/logs/clover.xml
+          token: ${{ secrets.CODECOV_TOKEN }}
+          verbose: true
+
+  testing:
+    timeout-minutes: 4
+    runs-on: ${{ matrix.os }}
+    concurrency:
+      cancel-in-progress: true
+      group: testing-${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}-${{ matrix.php-version }}-${{ matrix.dependencies }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os:
+          - ubuntu-latest
+        php-version:
+          - '8.1'
+          - '8.2'
+          - '8.3'
+          - '8.4'
+        dependencies:
+          - lowest
+          - locked
+          - highest
+    steps:
+      - name: 📦 Check out the codebase
+        uses: actions/checkout@v5
+
+      - name: 🛠️ Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php-version }}
+          ini-values: error_reporting=E_ALL
+
+      - name: 🛠️ Setup problem matchers
+        run: |
+          echo "::add-matcher::${{ runner.tool_cache }}/php.json"
+          echo "::add-matcher::${{ runner.tool_cache }}/phpunit.json"
+
+      - name: 🤖 Validate composer.json and composer.lock
+        run: composer validate --ansi --strict
+
+      - name: 📥 Install dependencies with composer
+        uses: ramsey/composer-install@v3
+        with:
+          dependency-versions: ${{ matrix.dependencies }}
+
+      - name: 🧪 Run tests
+        run: composer test