tdd-workflow

Test-Driven Development (TDD) Workflow

This skill is intended to ensure that all code development follows TDD principles and has comprehensive test coverage.

When to Enable

• Writing new features or new functionality
• Fixing bugs or issues
• Refactoring existing code
• Adding API endpoints
• Creating new components

Core Principles

1. Tests BEFORE Code

Always write tests first, then implement code to make the tests pass.

2. Coverage Requirements

• Minimum 80% coverage (unit tests + integration tests + E2E tests)
• Cover all edge cases
• Test error scenarios
• Verify boundary conditions

3. Test Types

Unit Tests

• Individual functions and utilities
• Component logic
• Pure functions
• Helpers and utilities

Integration Tests

• API endpoints
• Database operations
• Interactions between services
• External API calls

E2E Tests (Playwright)

• Critical user flows
• Complete workflows
• Browser automation
• UI interactions

TDD Workflow Steps

Step 1: Write User Journeys

作为 [角色]，我想 [动作]，以便 [获益]

示例：
作为一名用户，我想进行语义化的市场搜索，
以便即使没有精确的关键词也能找到相关的市场。

Step 2: Generate Test Cases

Create comprehensive test cases for each user journey:

describe('Semantic Search', () => {
  it('returns relevant markets for query', async () => {
    // 测试实现
  })

  it('handles empty query gracefully', async () => {
    // 测试边缘情况
  })

  it('falls back to substring search when Redis unavailable', async () => {
    // 测试回退行为
  })

  it('sorts results by similarity score', async () => {
    // 测试排序逻辑
  })
})

Step 3: Run Tests (Expected to Fail)

npm test
# 测试应该失败 - 因为我们尚未实现功能

Step 4: Implement Code

Write the minimum amount of code to make the tests pass:

// 由测试引导的实现
export async function searchMarkets(query: string) {
  // 此处为实现逻辑
}

Step 5: Run Tests Again

npm test
# 测试现在应该通过

Step 6: Refactor

Improve code quality while keeping tests passing:

• Eliminate duplication
• Improve naming
• Optimize performance
• Enhance readability

Step 7: Verify Coverage

npm run test:coverage
# 验证是否达到了 80% 以上的覆盖率

Testing Patterns

Unit Test Pattern (Jest/Vitest)

import { render, screen, fireEvent } from '@testing-library/react'
import { Button } from './Button'

describe('Button Component', () => {
  it('renders with correct text', () => {
    render(<Button>Click me</Button>)
    expect(screen.getByText('Click me')).toBeInTheDocument()
  })

  it('calls onClick when clicked', () => {
    const handleClick = jest.fn()
    render(<Button onClick={handleClick}>Click</Button>)

    fireEvent.click(screen.getByRole('button'))

    expect(handleClick).toHaveBeenCalledTimes(1)
  })

  it('is disabled when disabled prop is true', () => {
    render(<Button disabled>Click</Button>)
    expect(screen.getByRole('button')).toBeDisabled()
  })
})

API Integration Test Pattern

import { NextRequest } from 'next/server'
import { GET } from './route'

describe('GET /api/markets', () => {
  it('returns markets successfully', async () => {
    const request = new NextRequest('http://localhost/api/markets')
    const response = await GET(request)
    const data = await response.json()

    expect(response.status).toBe(200)
    expect(data.success).toBe(true)
    expect(Array.isArray(data.data)).toBe(true)
  })

  it('validates query parameters', async () => {
    const request = new NextRequest('http://localhost/api/markets?limit=invalid')
    const response = await GET(request)

    expect(response.status).toBe(400)
  })

  it('handles database errors gracefully', async () => {
    // 模拟数据库故障
    const request = new NextRequest('http://localhost/api/markets')
    // 测试错误处理
  })
})

E2E Test Pattern (Playwright)

import { test, expect } from '@playwright/test'

test('user can search and filter markets', async ({ page }) => {
  // 导航到市场页面
  await page.goto('/')
  await page.click('a[href="/markets"]')

  // 验证页面已加载
  await expect(page.locator('h1')).toContainText('Markets')

  // 搜索市场
  await page.fill('input[placeholder="Search markets"]', 'election')

  // 等待防抖处理和结果返回
  await page.waitForTimeout(600)

  // 验证搜索结果已显示
  const results = page.locator('[data-testid="market-card"]')
  await expect(results).toHaveCount(5, { timeout: 5000 })

  // 验证结果包含搜索词
  const firstResult = results.first()
  await expect(firstResult).toContainText('election', { ignoreCase: true })

  // 按状态过滤
  await page.click('button:has-text("Active")')

  // 验证过滤后的结果
  await expect(results).toHaveCount(3)
})

test('user can create a new market', async ({ page }) => {
  // 先登录
  await page.goto('/creator-dashboard')

  // 填写市场创建表单
  await page.fill('input[name="name"]', 'Test Market')
  await page.fill('textarea[name="description"]', 'Test description')
  await page.fill('input[name="endDate"]', '2025-12-31')

  // 提交表单
  await page.click('button[type="submit"]')

  // 验证成功消息
  await expect(page.locator('text=Market created successfully')).toBeVisible()

  // 验证重定向到市场详情页
  await expect(page).toHaveURL(/\/markets\/test-market/)
})

Test File Organization

src/
├── components/
│   ├── Button/
│   │   ├── Button.tsx
│   │   ├── Button.test.tsx          # 单元测试
│   │   └── Button.stories.tsx       # Storybook
│   └── MarketCard/
│       ├── MarketCard.tsx
│       └── MarketCard.test.tsx
├── app/
│   └── api/
│       └── markets/
│           ├── route.ts
│           └── route.test.ts         # 集成测试
└── e2e/
    ├── markets.spec.ts               # E2E 测试
    ├── trading.spec.ts
    └── auth.spec.ts

Mocking External Services

Supabase Mocking

jest.mock('@/lib/supabase', () => ({
  supabase: {
    from: jest.fn(() => ({
      select: jest.fn(() => ({
        eq: jest.fn(() => Promise.resolve({
          data: [{ id: 1, name: 'Test Market' }],
          error: null
        }))
      }))
    }))
  }
}))

Redis Mocking

jest.mock('@/lib/redis', () => ({
  searchMarketsByVector: jest.fn(() => Promise.resolve([
    { slug: 'test-market', similarity_score: 0.95 }
  ])),
  checkRedisHealth: jest.fn(() => Promise.resolve({ connected: true }))
}))

OpenAI Mocking

jest.mock('@/lib/openai', () => ({
  generateEmbedding: jest.fn(() => Promise.resolve(
    new Array(1536).fill(0.1) // 模拟 1536 维向量嵌入
  ))
}))

Test Coverage Verification

Run Coverage Report

npm run test:coverage

Coverage Threshold

{
  "jest": {
    "coverageThresholds": {
      "global": {
        "branches": 80,
        "functions": 80,
        "lines": 80,
        "statements": 80
      }
    }
  }
}

Common Testing Mistakes to Avoid

❌ Wrong Practice: Testing Implementation Details

// 不要测试内部状态
expect(component.state.count).toBe(5)

✅ Correct Practice: Test User-Visible Behavior

// 测试用户看到的内容
expect(screen.getByText('Count: 5')).toBeInTheDocument()

❌ Wrong Practice: Using Fragile Selectors

// 极易因样式更改而失败
await page.click('.css-class-xyz')

✅ Correct Practice: Use Semantic Selectors

// 对更改具有弹性
await page.click('button:has-text("Submit")')
await page.click('[data-testid="submit-button"]')

❌ Wrong Practice: Lack of Isolation Between Tests

// 测试相互依赖
test('creates user', () => { /* ... */ })
test('updates same user', () => { /* 依赖于前一个测试的结果 */ })

✅ Correct Practice: Independent Tests

// 每个测试都设置自己的数据
test('creates user', () => {
  const user = createTestUser()
  // 测试逻辑
})

test('updates user', () => {
  const user = createTestUser()
  // 更新逻辑
})

Continuous Testing

Watch Mode During Development

npm test -- --watch
# 文件更改时自动运行测试

Pre-commit hooks

# 在每次提交前运行
npm test && npm run lint

CI/CD integration

# GitHub Actions
- name: Run Tests
  run: npm test -- --coverage
- name: Upload Coverage
  uses: codecov/codecov-action@v3

Best practices

1. Write tests first - Always follow TDD
2. One assertion per test - Focus on a single behavior
3. Descriptive test names - Explain what is being tested
4. Arrange-Act-Assert - Clear test structure
5. Mock external dependencies - Isolate unit tests
6. Test edge cases - null, undefined, empty values, oversized values
7. Test error paths - Not just "Happy paths"
8. Keep tests fast - Each unit test < 50ms
9. Clean up after tests - Avoid side effects
10. Review coverage reports - Identify missing gaps

Success metrics

• Achieve over 80% code coverage
• All tests pass (shown as green)
• No skipped or disabled tests
• Fast test execution (unit tests < 30s)
• E2E tests cover key user flows
• Tests can catch bugs before they reach production

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Remember: Tests are not optional. They are the safety net that gives you the confidence to refactor, develop quickly, and ensure production reliability.