Add comprehensive test suite for Result library

.github/workflows/test.yml

@@ -0,0 +1,63 @@
+name: Tests
+
+on:
+  push:
+    branches: [ main, develop ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    name: PHP 8.4 Tests
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup PHP 8.4
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: '8.4'
+          coverage: xdebug
+          tools: composer:v2
+
+      - name: Validate composer.json
+        run: composer validate --strict
+
+      - name: Cache Composer packages
+        uses: actions/cache@v3
+        with:
+          path: vendor
+          key: ${{ runner.os }}-php-8.4-${{ hashFiles('**/composer.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-php-8.4-
+
+      - name: Install dependencies
+        run: composer install --prefer-dist --no-progress
+
+      - name: Run tests
+        run: composer test
+
+      - name: Generate coverage report
+        run: ./vendor/bin/phpunit --coverage-clover coverage.xml
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v3
+        with:
+          file: ./coverage.xml
+          flags: unittests
+          name: codecov-umbrella
+          fail_ci_if_error: false
+
+  docker-test:
+    runs-on: ubuntu-latest
+    name: Docker Test
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Build Docker image
+        run: docker build -t php-result-test .
+
+      - name: Run tests in Docker
+        run: docker run --rm -v "$(pwd)":/app php-result-test ./vendor/bin/phpunit --testdox

.gitignore

@@ -2,6 +2,7 @@
 /composer.lock
 /.phpstan/
 /.phpunit.cache/
+/.phpunit.result.cache
 /coverage/
 .DS_Store
 /.php-cs-fixer.cache