# Testing Strategies and Framework Guide

## Overview

This document establishes comprehensive testing strategies, frameworks, and best practices for ensuring software quality across all development projects. Our testing approach follows the testing pyramid principle with emphasis on automation and continuous feedback.

## Testing Strategy Overview

### Testing Pyramid

```
    /\
   /  \     E2E Tests (Few)
  /____\    
 /      \   Integration Tests (Some)
/__________\ Unit Tests (Many)
```

**Test Distribution:**
- **Unit Tests**: 70% - Fast, isolated, comprehensive coverage
- **Integration Tests**: 20% - Component interaction validation
- **End-to-End Tests**: 10% - Critical user journey validation

### Testing Principles

**Core Principles:**
- **Fast Feedback**: Tests should provide quick feedback to developers
- **Reliable**: Tests should be deterministic and stable
- **Maintainable**: Tests should be easy to understand and modify
- **Comprehensive**: Critical functionality must be thoroughly tested
- **Automated**: Manual testing only for exploratory and usability testing

## Unit Testing Standards

### Unit Test Requirements

**Coverage Requirements:**
- Minimum 80% code coverage for all new code
- 90% coverage for critical business logic
- 100% coverage for security-related functions
- Branch coverage in addition to line coverage

**Test Structure (AAA Pattern):**
```python
def test_user_creation_with_valid_data():
    # Arrange
    user_data = {
        "name": "John Doe",
        "email": "john@example.com",
        "age": 30
    }
    
    # Act
    user = User.create(user_data)
    
    # Assert
    assert user.name == "John Doe"
    assert user.email == "john@example.com"
    assert user.is_active is True
```

### Testing Frameworks by Language

**Python Testing Stack:**
```python
# pytest configuration (pytest.ini)
[tool:pytest]
testpaths = tests
python_files = test_*.py
python_classes = Test*
python_functions = test_*
addopts = 
    --cov=src
    --cov-report=html
    --cov-report=term-missing
    --cov-fail-under=80
    --strict-markers
    --disable-warnings

# Example test with fixtures
import pytest
from unittest.mock import Mock, patch

@pytest.fixture
def user_service():
    return UserService(database=Mock())

def test_get_user_by_id(user_service):
    # Test implementation
    pass

@patch('external_service.api_call')
def test_external_integration(mock_api):
    mock_api.return_value = {"status": "success"}
    # Test implementation
```

**JavaScript/TypeScript Testing Stack:**
```javascript
// Jest configuration (jest.config.js)
module.exports = {
  testEnvironment: 'node',
  coverageDirectory: 'coverage',
  collectCoverageFrom: [
    'src/**/*.{js,ts}',
    '!src/**/*.d.ts',
    '!src/**/*.test.{js,ts}'
  ],
  coverageThreshold: {
    global: {
      branches: 80,
      functions: 80,
      lines: 80,
      statements: 80
    }
  },
  setupFilesAfterEnv: ['<rootDir>/tests/setup.js']
};

// Example test with mocking
import { UserService } from '../src/services/UserService';
import { DatabaseClient } from '../src/database/DatabaseClient';

jest.mock('../src/database/DatabaseClient');

describe('UserService', () => {
  let userService: UserService;
  let mockDatabase: jest.Mocked<DatabaseClient>;

  beforeEach(() => {
    mockDatabase = new DatabaseClient() as jest.Mocked<DatabaseClient>;
    userService = new UserService(mockDatabase);
  });

  test('should create user with valid data', async () => {
    const userData = { name: 'John Doe', email: 'john@example.com' };
    mockDatabase.save.mockResolvedValue({ id: 1, ...userData });

    const result = await userService.createUser(userData);

    expect(result.id).toBe(1);
    expect(mockDatabase.save).toHaveBeenCalledWith(userData);
  });
});
```

### Mocking and Test Doubles

**Mocking Guidelines:**
- Mock external dependencies (APIs, databases, file systems)
- Use dependency injection for easier testing
- Prefer test doubles over real implementations
- Verify interactions with mocks when behavior matters

**Mock Types:**
- **Dummy**: Objects passed but never used
- **Fake**: Working implementations with shortcuts
- **Stubs**: Provide canned answers to calls
- **Spies**: Record information about calls
- **Mocks**: Pre-programmed with expectations

## Integration Testing

### Integration Test Categories

**Component Integration Tests:**
- Database integration tests
- API integration tests
- Message queue integration tests
- External service integration tests

**Contract Testing:**
- Provider contract tests
- Consumer contract tests
- API contract validation
- Schema compatibility tests

### Database Integration Testing

**Test Database Setup:**
```python
# pytest fixture for database testing
@pytest.fixture(scope="function")
def test_db():
    # Setup test database
    engine = create_engine("sqlite:///:memory:")
    Base.metadata.create_all(engine)
    
    session = Session(engine)
    yield session
    
    # Cleanup
    session.close()

def test_user_repository_save(test_db):
    repo = UserRepository(test_db)
    user = User(name="John Doe", email="john@example.com")
    
    saved_user = repo.save(user)
    
    assert saved_user.id is not None
    assert repo.find_by_id(saved_user.id) == saved_user
```

**Database Test Strategies:**
- Use in-memory databases for fast tests
- Use containerized databases for realistic tests
- Implement database rollback after each test
- Use database fixtures for complex scenarios

### API Integration Testing

**REST API Testing:**
```python
import requests
import pytest

@pytest.fixture
def api_client():
    return requests.Session()

def test_user_api_create_and_retrieve(api_client):
    # Create user
    user_data = {"name": "John Doe", "email": "john@example.com"}
    create_response = api_client.post("/api/users", json=user_data)
    
    assert create_response.status_code == 201
    user_id = create_response.json()["id"]
    
    # Retrieve user
    get_response = api_client.get(f"/api/users/{user_id}")
    
    assert get_response.status_code == 200
    assert get_response.json()["name"] == "John Doe"
```

**GraphQL Testing:**
```javascript
import { createTestClient } from 'apollo-server-testing';
import { gql } from 'apollo-server-express';

const GET_USER = gql`
  query GetUser($id: ID!) {
    user(id: $id) {
      id
      name
      email
    }
  }
`;

test('should fetch user by id', async () => {
  const { query } = createTestClient(server);
  
  const response = await query({
    query: GET_USER,
    variables: { id: '1' }
  });
  
  expect(response.errors).toBeUndefined();
  expect(response.data.user.name).toBe('John Doe');
});
```

## End-to-End Testing

### E2E Testing Strategy

**Test Scope:**
- Critical user journeys
- Cross-browser compatibility
- Mobile responsiveness
- Performance under load
- Security vulnerabilities

**E2E Test Framework Selection:**
```javascript
// Playwright configuration
import { defineConfig } from '@playwright/test';

export default defineConfig({
  testDir: './e2e',
  timeout: 30000,
  retries: 2,
  use: {
    baseURL: 'http://localhost:3000',
    trace: 'on-first-retry',
    screenshot: 'only-on-failure'
  },
  projects: [
    { name: 'chromium', use: { ...devices['Desktop Chrome'] } },
    { name: 'firefox', use: { ...devices['Desktop Firefox'] } },
    { name: 'webkit', use: { ...devices['Desktop Safari'] } },
    { name: 'mobile', use: { ...devices['iPhone 12'] } }
  ]
});

// Example E2E test
import { test, expect } from '@playwright/test';

test('user registration flow', async ({ page }) => {
  await page.goto('/register');
  
  await page.fill('[data-testid="name-input"]', 'John Doe');
  await page.fill('[data-testid="email-input"]', 'john@example.com');
  await page.fill('[data-testid="password-input"]', 'SecurePassword123');
  
  await page.click('[data-testid="register-button"]');
  
  await expect(page).toHaveURL('/dashboard');
  await expect(page.locator('[data-testid="welcome-message"]')).toContainText('Welcome, John Doe');
});
```

### Visual Regression Testing

**Visual Testing Setup:**
```javascript
// Percy configuration for visual testing
import { percySnapshot } from '@percy/playwright';

test('homepage visual regression', async ({ page }) => {
  await page.goto('/');
  await percySnapshot(page, 'Homepage');
});

// Chromatic for Storybook components
import { getStorybook, configure } from '@storybook/testing-react';

configure(require.context('../src', true, /\.stories\.js$/));

test('button component visual regression', () => {
  const storybook = getStorybook();
  // Visual regression testing for components
});
```

## Performance Testing

### Performance Test Categories

**Load Testing:**
- Normal expected load simulation
- Gradual load increase testing
- Sustained load testing
- Spike testing

**Stress Testing:**
- Beyond normal capacity testing
- Breaking point identification
- Recovery testing
- Resource exhaustion testing

### Performance Testing Tools

**K6 Load Testing:**
```javascript
import http from 'k6/http';
import { check, sleep } from 'k6';

export let options = {
  stages: [
    { duration: '2m', target: 100 }, // Ramp up
    { duration: '5m', target: 100 }, // Stay at 100 users
    { duration: '2m', target: 200 }, // Ramp up to 200 users
    { duration: '5m', target: 200 }, // Stay at 200 users
    { duration: '2m', target: 0 },   // Ramp down
  ],
  thresholds: {
    http_req_duration: ['p(95)<500'], // 95% of requests under 500ms
    http_req_failed: ['rate<0.1'],    // Error rate under 10%
  },
};

export default function () {
  let response = http.get('https://api.example.com/users');
  
  check(response, {
    'status is 200': (r) => r.status === 200,
    'response time < 500ms': (r) => r.timings.duration < 500,
  });
  
  sleep(1);
}
```

**Artillery Configuration:**
```yaml
# artillery.yml
config:
  target: 'https://api.example.com'
  phases:
    - duration: 60
      arrivalRate: 10
    - duration: 120
      arrivalRate: 50
  defaults:
    headers:
      Authorization: 'Bearer {{ $randomString() }}'

scenarios:
  - name: "User API Load Test"
    flow:
      - get:
          url: "/users"
      - think: 1
      - post:
          url: "/users"
          json:
            name: "{{ $randomString() }}"
            email: "{{ $randomString() }}@example.com"
```

## Security Testing

### Security Test Categories

**Static Application Security Testing (SAST):**
- Source code vulnerability scanning
- Dependency vulnerability scanning
- Configuration security analysis
- Secrets detection

**Dynamic Application Security Testing (DAST):**
- Runtime vulnerability scanning
- Penetration testing automation
- API security testing
- Authentication and authorization testing

### Security Testing Implementation

**OWASP ZAP Integration:**
```python
# Security testing with ZAP
from zapv2 import ZAPv2

def test_api_security():
    zap = ZAPv2(proxies={'http': 'http://127.0.0.1:8080'})
    
    # Spider the application
    zap.spider.scan('https://api.example.com')
    
    # Active security scan
    zap.ascan.scan('https://api.example.com')
    
    # Get alerts
    alerts = zap.core.alerts()
    
    # Assert no high-risk vulnerabilities
    high_risk_alerts = [alert for alert in alerts if alert['risk'] == 'High']
    assert len(high_risk_alerts) == 0, f"High risk vulnerabilities found: {high_risk_alerts}"
```

**Dependency Security Testing:**
```bash
# npm audit for Node.js
npm audit --audit-level high

# Safety for Python
safety check --json

# Snyk for multiple languages
snyk test --severity-threshold=high
```

## Test Data Management

### Test Data Strategies

**Test Data Categories:**
- **Static Test Data**: Predefined datasets for consistent testing
- **Generated Test Data**: Dynamically created data for each test
- **Anonymized Production Data**: Sanitized real data for realistic testing
- **Synthetic Test Data**: AI-generated realistic data

**Test Data Factory Pattern:**
```python
# Factory pattern for test data
class UserFactory:
    @staticmethod
    def create_user(**kwargs):
        defaults = {
            "name": "John Doe",
            "email": "john@example.com",
            "age": 30,
            "is_active": True
        }
        defaults.update(kwargs)
        return User(**defaults)
    
    @staticmethod
    def create_admin_user(**kwargs):
        defaults = {"role": "admin", "permissions": ["read", "write", "delete"]}
        defaults.update(kwargs)
        return UserFactory.create_user(**defaults)

# Usage in tests
def test_user_permissions():
    admin = UserFactory.create_admin_user()
    regular_user = UserFactory.create_user()
    
    assert admin.can_delete()
    assert not regular_user.can_delete()
```

### Test Environment Management

**Environment Configuration:**
```yaml
# Test environment configuration
test:
  database:
    url: "postgresql://test:test@localhost:5432/testdb"
    pool_size: 5
  redis:
    url: "redis://localhost:6379/1"
  external_services:
    payment_api:
      url: "https://sandbox.payment.com"
      api_key: "test_key_123"
  feature_flags:
    new_user_flow: true
    advanced_analytics: false
```

## Continuous Testing Integration

### CI/CD Pipeline Integration

**Pipeline Test Stages:**
```yaml
# GitHub Actions workflow
name: Test Pipeline
on: [push, pull_request]

jobs:
  unit-tests:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - name: Run Unit Tests
        run: |
          npm install
          npm run test:unit
          npm run test:coverage
  
  integration-tests:
    runs-on: ubuntu-latest
    services:
      postgres:
        image: postgres:13
        env:
          POSTGRES_PASSWORD: test
    steps:
      - uses: actions/checkout@v3
      - name: Run Integration Tests
        run: npm run test:integration
  
  e2e-tests:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - name: Run E2E Tests
        run: |
          npm run build
          npm run start:test &
          npm run test:e2e
  
  security-tests:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - name: Security Scan
        run: |
          npm audit --audit-level high
          npm run test:security
```

### Test Reporting and Analytics

**Test Metrics Collection:**
- Test execution time trends
- Test failure rates and patterns
- Code coverage trends
- Flaky test identification
- Test maintenance overhead

**Reporting Tools:**
- **Allure**: Comprehensive test reporting
- **ReportPortal**: Test analytics and ML-powered insights
- **TestRail**: Test case management and reporting
- **Custom Dashboards**: Grafana/Kibana for metrics visualization

## Test Maintenance and Quality

### Test Code Quality Standards

**Test Code Guidelines:**
- Tests should be as maintainable as production code
- Use descriptive test names that explain the scenario
- Keep tests independent and isolated
- Avoid test logic complexity
- Use appropriate assertion libraries

**Test Naming Conventions:**
```python
# Good test names
def test_user_creation_with_valid_email_returns_success():
    pass

def test_user_creation_with_invalid_email_raises_validation_error():
    pass

def test_user_deletion_by_admin_removes_user_from_database():
    pass

# Bad test names
def test_user():
    pass

def test_create():
    pass

def test_validation():
    pass
```

### Flaky Test Management

**Flaky Test Identification:**
- Automated flaky test detection
- Test execution history analysis
- Environmental dependency identification
- Timing-related issue detection

**Flaky Test Resolution:**
- Add explicit waits instead of sleep
- Use test isolation techniques
- Mock external dependencies
- Implement retry mechanisms for legitimate flakiness

### Test Refactoring

**When to Refactor Tests:**
- Tests become difficult to understand
- Tests are tightly coupled to implementation
- Tests have high maintenance overhead
- Tests provide little value or confidence

**Refactoring Techniques:**
- Extract common setup into fixtures
- Use page object pattern for UI tests
- Create domain-specific test utilities
- Implement test data builders

## Training and Best Practices

### Developer Training Requirements

**Testing Skills Development:**
- Unit testing fundamentals and TDD
- Integration testing strategies
- E2E testing best practices
- Performance testing techniques
- Security testing awareness

**Framework-Specific Training:**
- Language-specific testing frameworks
- Mocking and stubbing techniques
- Test automation tools
- CI/CD integration practices

### Testing Community of Practice

**Knowledge Sharing:**
- Regular testing guild meetings
- Best practice documentation
- Code review focus on test quality
- Testing workshop and training sessions

**Continuous Improvement:**
- Regular testing process retrospectives
- Tool evaluation and adoption
- Industry best practice research
- Testing metrics analysis and optimization
