Add test execution to GitHub Actions workflow with best practices

- Run tests before building Docker image
- Use latest action versions (checkout@v4, setup-python@v5, upload-artifact@v4)
- Enable pip dependency caching for faster builds
- Generate both XML coverage and JUnit test reports
- Upload test results as artifacts for debugging
- Tests must pass before Docker build proceeds

Follows GitHub's recommended Python testing practices for CI/CD.

Author: IvanBiruk

.github/workflows/main.yml

@@ -17,6 +17,34 @@ jobs:
       contents: read
       packages: write
     steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+          cache: 'pip'
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install -e .
+          pip install pytest pytest-asyncio pytest-mock pytest-cov
+
+      - name: Run tests
+        run: |
+          python -m pytest src/tests/ -v --cov=src --cov-report=term-missing --cov-report=xml --junitxml=junit/test-results.xml
+
+      - name: Upload test results
+        uses: actions/upload-artifact@v4
+        if: always()
+        with:
+          name: pytest-results
+          path: |
+            junit/test-results.xml
+            coverage.xml
+
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v2
       - name: Docker meta