tests/README.md

Backend Tests - Feature 006: Urdu Translation

Test Structure

tests/
├── unit/
│   └── test_translation_service.py      # TranslationService unit tests
├── integration/
│   └── test_translation_endpoint.py     # API endpoint integration tests
└── README.md                             # This file

Test Coverage

Unit Tests (T011)

File: tests/unit/test_translation_service.py

• ✅ test_openrouter_client_initialization - Verify OpenAI client configured with OpenRouter
• ✅ test_translate_to_urdu_success - Mock API response, verify translation
• ✅ test_translate_to_urdu_preserves_technical_terms - Verify ROS2, Python stay in English
• ✅ test_translate_to_urdu_uses_cache - Verify caching mechanism
• ✅ test_translate_to_urdu_retry_logic - Verify exponential backoff on errors
• ✅ test_translate_to_urdu_cache_expiry - Verify TTL-based cache expiry
• ✅ test_translate_to_english_success - Verify reverse translation
• ✅ test_system_prompt_exists - Verify system prompt method

Total: 8 test cases

Integration Tests (T012)

File: tests/integration/test_translation_endpoint.py

Authentication Tests:

• ✅ test_translation_endpoint_authenticated - POST with JWT, verify 200
• ✅ test_translation_endpoint_unauthenticated - POST without JWT, verify 401
• ✅ test_translation_endpoint_invalid_token - POST with invalid JWT, verify 401

Caching Tests:

• ✅ test_translation_endpoint_cache_miss - First translation, verify cached: false
• ✅ test_translation_endpoint_cache_hit - Second translation, verify cached: true

Validation Tests:

• ✅ test_translation_endpoint_content_hash_mismatch - Send mismatched hash, verify 400
• ✅ test_translation_endpoint_missing_fields - Send incomplete request, verify 422

Rate Limiting Tests:

• ✅ test_translation_endpoint_rate_limit_exceeded - Exceed limit, verify 429 with Retry-After

Stats Tests:

• ✅ test_get_translation_stats - GET /translate/stats, verify quota info

Health Check:

• ✅ test_translation_health_endpoint - GET /translation/health, verify status

Total: 10 test cases

Running Tests

Prerequisites

Install pytest and dependencies:

cd backend
pip install pytest pytest-mock pytest-asyncio httpx

Run All Tests

# Run all tests with verbose output
pytest tests/ -v

# Run with coverage
pytest tests/ --cov=api --cov=services --cov-report=html

# Run specific test file
pytest tests/unit/test_translation_service.py -v
pytest tests/integration/test_translation_endpoint.py -v

Run Specific Test

# Run single test case
pytest tests/unit/test_translation_service.py::TestTranslationServiceInitialization::test_openrouter_client_initialization -v

# Run test class
pytest tests/unit/test_translation_service.py::TestTranslateToUrdu -v

Run with Output

# Show print statements
pytest tests/ -v -s

# Show detailed error traces
pytest tests/ -v --tb=long

Expected Results

TDD Approach

Following TDD principles, tests are written FIRST to define expected behavior:

1. Write tests - Define what the code should do
2. Run tests - Verify they FAIL (red phase)
3. Implement code - Make tests PASS (green phase)
4. Refactor - Improve code while keeping tests green

Current Status

All tests are written and should PASS with current implementation:

• ✅ Unit tests validate TranslationService behavior
• ✅ Integration tests validate API endpoints
• ✅ Mocking used for external dependencies (OpenRouter API, database)

Test Configuration

pytest.ini (Optional)

Create backend/pytest.ini for configuration:

[pytest]
testpaths = tests
python_files = test_*.py
python_classes = Test*
python_functions = test_*
addopts = -v --tb=short --strict-markers
markers =
    unit: Unit tests
    integration: Integration tests
    slow: Slow running tests

Running by Marker

# Run only unit tests
pytest -m unit

# Run only integration tests
pytest -m integration

# Skip slow tests
pytest -m "not slow"

Continuous Integration

Add to GitHub Actions workflow (.github/workflows/test.yml):

name: Backend Tests

on: [push, pull_request]

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: Set up Python
        uses: actions/setup-python@v2
        with:
          python-version: '3.11'
      - name: Install dependencies
        run: |
          cd backend
          pip install -r requirements.txt
          pip install pytest pytest-mock pytest-asyncio httpx
      - name: Run tests
        run: |
          cd backend
          pytest tests/ -v --tb=short

Troubleshooting

Import Errors

If you get import errors, add backend to PYTHONPATH:

export PYTHONPATH="${PYTHONPATH}:/path/to/backend"
pytest tests/ -v

Or run from backend directory:

cd backend
python -m pytest tests/ -v

Mock Issues

If mocks aren't working, verify patch paths:

# Correct: patch where it's used
@patch('api.translation.translation_service')

# Incorrect: patch where it's defined
@patch('services.translation_service.TranslationService')

Database Tests

Integration tests use mocked database. To test with real database:

1. Set up test database
2. Remove DB_ENABLED patches
3. Use transactions and rollback after each test

Next Steps

• Add E2E tests with Playwright
• Add performance tests (load testing)
• Add security tests (injection, XSS)
• Increase coverage to 90%+
• Add mutation testing