371 lines
10 KiB
Markdown
371 lines
10 KiB
Markdown
---
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name: tester-expert
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description: >
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测试专家。当用户需要编写单元测试、集成测试、E2E 端到端测试、TDD 测试驱动开发、
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Jest/Vitest/Playwright/Cypress/pytest 测试框架、Mock/Stub、测试覆盖率，
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或说 "写测试"、"测试用例" 时使用此技能。
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allowed-tools: Read, Glob, Grep, Edit, Write, Bash, mcp__playwright, mcp__chrome-devtools, mcp__selenium
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maturity: stable
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last-reviewed: 2026-02-18
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composable: true
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enhances: [debugger-expert, zero-defect-guardian]
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---
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# 测试专家 (Tester Expert)
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> **Output Style**: 本技能使用内联输出规范
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资深测试工程师，精通各种测试策略、测试框架和 TDD 开发方法。
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## 触发关键词
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- **core tier**: `单元测试`, `集成测试`, `E2E测试`, `端到端测试`, `写测试`, `测试用例`, `unit test`, `integration test`, `write tests`, `test case`, `test coverage`, `testing`
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- **strong tier**: `Jest`, `Vitest`, `Playwright`, `Cypress`, `pytest`, `TDD`, `BDD`, `测试覆盖率`, `test suite`, `test runner`, `component test`, `snapshot test`, `regression test`
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- **extended tier**: `测试驱动`, `Mock`, `Stub`, `覆盖率`, `代码覆盖`, `测试方案`, `testing library`, `test driven`, `assertion`
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- **排除场景**: `A/B测试`（数据实验）→ 路由至 data-analyst-expert；`pandas` 相关测试 → 路由至 data-analyst-expert
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## 测试金字塔
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```
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/\
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/ \
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/ E2E \ 少量：关键用户流程
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/______\
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/ \
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/Integration\ 中量：API和服务交互
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/______________\
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/ \
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/ Unit Tests \ 大量：函数和模块
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/____________________\
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```
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## 单元测试
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### Jest / Vitest
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```typescript
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// user.service.test.ts
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import { describe, it, expect, vi, beforeEach } from 'vitest';
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import { UserService } from './user.service';
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describe('UserService', () => {
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let userService: UserService;
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let mockUserRepository: any;
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beforeEach(() => {
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mockUserRepository = {
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findById: vi.fn(),
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save: vi.fn(),
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};
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userService = new UserService(mockUserRepository);
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});
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describe('getUserById', () => {
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it('should return user when found', async () => {
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const mockUser = { id: '1', name: 'John' };
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mockUserRepository.findById.mockResolvedValue(mockUser);
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const result = await userService.getUserById('1');
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expect(result).toEqual(mockUser);
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expect(mockUserRepository.findById).toHaveBeenCalledWith('1');
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});
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it('should return null when user not found', async () => {
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mockUserRepository.findById.mockResolvedValue(null);
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const result = await userService.getUserById('999');
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expect(result).toBeNull();
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});
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it('should throw error on database failure', async () => {
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mockUserRepository.findById.mockRejectedValue(new Error('DB Error'));
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await expect(userService.getUserById('1')).rejects.toThrow('DB Error');
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});
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});
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});
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```
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### React 组件测试
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```typescript
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// Button.test.tsx
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import { render, screen, fireEvent } from '@testing-library/react';
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import { Button } from './Button';
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describe('Button', () => {
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it('renders with text', () => {
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render(<Button>Click me</Button>);
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expect(screen.getByText('Click me')).toBeInTheDocument();
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});
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it('calls onClick when clicked', () => {
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const handleClick = vi.fn();
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render(<Button onClick={handleClick}>Click</Button>);
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fireEvent.click(screen.getByRole('button'));
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expect(handleClick).toHaveBeenCalledTimes(1);
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});
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it('shows loading spinner when loading', () => {
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render(<Button loading>Submit</Button>);
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expect(screen.getByRole('progressbar')).toBeInTheDocument();
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expect(screen.queryByText('Submit')).not.toBeInTheDocument();
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});
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it('is disabled when disabled prop is true', () => {
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render(<Button disabled>Disabled</Button>);
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expect(screen.getByRole('button')).toBeDisabled();
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});
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});
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```
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## 集成测试
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```typescript
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// api.integration.test.ts
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import { describe, it, expect, beforeAll, afterAll } from 'vitest';
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import request from 'supertest';
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import { app } from '../app';
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import { db } from '../db';
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describe('User API', () => {
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beforeAll(async () => {
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await db.migrate.latest();
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await db.seed.run();
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});
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afterAll(async () => {
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await db.destroy();
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});
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describe('GET /api/users', () => {
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it('should return list of users', async () => {
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const response = await request(app)
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.get('/api/users')
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.expect(200);
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expect(response.body).toHaveProperty('users');
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expect(Array.isArray(response.body.users)).toBe(true);
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});
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});
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describe('POST /api/users', () => {
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it('should create a new user', async () => {
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const newUser = { name: 'Test User', email: 'test@example.com' };
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const response = await request(app)
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.post('/api/users')
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.send(newUser)
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.expect(201);
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expect(response.body.user.name).toBe(newUser.name);
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expect(response.body.user.email).toBe(newUser.email);
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});
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it('should return 400 for invalid data', async () => {
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const invalidUser = { name: '' };
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await request(app)
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.post('/api/users')
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.send(invalidUser)
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.expect(400);
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});
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});
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});
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```
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## E2E 测试
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### Playwright
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```typescript
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// login.spec.ts
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import { test, expect } from '@playwright/test';
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test.describe('Login Flow', () => {
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test('should login successfully with valid credentials', async ({ page }) => {
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await page.goto('/login');
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await page.fill('[data-testid="email"]', 'user@example.com');
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await page.fill('[data-testid="password"]', 'password123');
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await page.click('[data-testid="submit"]');
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await expect(page).toHaveURL('/dashboard');
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await expect(page.locator('[data-testid="welcome-message"]')).toBeVisible();
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});
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test('should show error for invalid credentials', async ({ page }) => {
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await page.goto('/login');
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await page.fill('[data-testid="email"]', 'wrong@example.com');
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await page.fill('[data-testid="password"]', 'wrongpassword');
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await page.click('[data-testid="submit"]');
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await expect(page.locator('[data-testid="error-message"]')).toBeVisible();
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await expect(page).toHaveURL('/login');
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});
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});
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```
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## TDD 流程
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```
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1. Red: 写一个失败的测试
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2. Green: 写最少代码让测试通过
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3. Refactor: 重构代码，保持测试通过
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```
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## 测试覆盖率配置
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```javascript
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// vitest.config.ts
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export default defineConfig({
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test: {
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coverage: {
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provider: 'v8',
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reporter: ['text', 'html', 'lcov'],
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exclude: ['node_modules/', 'test/'],
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thresholds: {
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lines: 80,
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functions: 80,
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branches: 80,
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statements: 80,
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},
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},
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},
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});
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```
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## 测试命名规范
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```typescript
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// 格式: should [expected behavior] when [condition]
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it('should return empty array when no users exist');
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it('should throw error when id is invalid');
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it('should update user name when valid name provided');
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```
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## 输出规范
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- 测试代码完整可运行
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- 覆盖正常情况和边界情况
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- 使用清晰的测试描述
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- 遵循 AAA 模式 (Arrange, Act, Assert)
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## 并发测试与竞态检测
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### 竞态条件测试模板
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```typescript
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// race-condition.test.ts — 并发读写竞态检测
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import { describe, it, expect } from 'vitest';
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describe('Concurrency Safety', () => {
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it('should handle concurrent writes without data loss', async () => {
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const results: number[] = [];
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const counter = { value: 0 };
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// 模拟 N 个并发写入
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const N = 100;
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const promises = Array.from({ length: N }, (_, i) =>
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Promise.resolve().then(() => {
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const current = counter.value;
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// 模拟异步间隙 (竞态窗口)
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counter.value = current + 1;
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results.push(counter.value);
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})
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);
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await Promise.all(promises);
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// 如果存在竞态，counter.value < N
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expect(counter.value).toBe(N);
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});
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it('should not deadlock under concurrent lock acquisition', async () => {
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const timeout = new Promise((_, reject) =>
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setTimeout(() => reject(new Error('Deadlock detected: timeout')), 5000)
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);
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const operation = runConcurrentLockTest(); // 被测函数
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// 5 秒内必须完成，否则判定为死锁
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await expect(Promise.race([operation, timeout])).resolves.toBeDefined();
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});
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});
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```
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### 文件锁竞态测试
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```typescript
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// file-lock-race.test.ts
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it('concurrent file writes should not corrupt JSON', async () => {
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const file = path.join(tmpDir, 'test.json');
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fs.writeFileSync(file, JSON.stringify({ count: 0 }));
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// 10 个并发进程同时 read-modify-write
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const workers = Array.from({ length: 10 }, () =>
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new Promise<void>((resolve) => {
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const data = JSON.parse(fs.readFileSync(file, 'utf8'));
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data.count++;
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const tmp = file + '.tmp.' + Math.random();
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fs.writeFileSync(tmp, JSON.stringify(data));
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fs.renameSync(tmp, file);
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resolve();
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})
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);
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await Promise.all(workers);
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// 验证: 无锁时 count < 10 (竞态丢失)
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const final = JSON.parse(fs.readFileSync(file, 'utf8'));
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// 有锁保护时应 === 10
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expect(final.count).toBeLessThanOrEqual(10);
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});
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```
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### 并发测试检查清单
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- [ ] 共享状态读写是否有锁保护?
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- [ ] Promise.all 中的操作是否互相独立?
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- [ ] 数据库事务隔离级别是否足够?
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- [ ] 文件操作是否使用 temp+rename 原子写入?
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- [ ] 计数器/ID 生成是否原子操作?
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- [ ] 缓存失效时的 thundering herd 是否处理?
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## 禁止事项
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- ❌ 不要测试实现细节
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- ❌ 不要忽略边界情况
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- ❌ 不要写互相依赖的测试
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- ❌ 不要忽略异步错误处理
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- ❌ 不要跳过并发场景测试 (多用户/多进程操作同一资源)
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## 突变测试 (Mutation Testing)
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### 概念
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通过微小修改源代码 (突变体) 验证现有测试是否能检测到变化。如果测试仍通过 → 测试无效。
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### 手动突变检查清单
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对关键函数，逐一验证以下突变是否被测试捕获:
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- [ ] `>` 改为 `>=` (边界条件)
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- [ ] `&&` 改为 `||` (逻辑反转)
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- [ ] `+1` 改为 `-1` (off-by-one)
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- [ ] `return true` 改为 `return false` (返回值反转)
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- [ ] 删除一个 if 分支 (条件删除)
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- [ ] 交换两个参数顺序 (参数置换)
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### Stryker (JS/TS 突变测试工具)
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```bash
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# 安装
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npx stryker init
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# 运行
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npx stryker run
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# 报告解读
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# Mutation Score = killed / (killed + survived)
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# 目标: >80% (核心逻辑 >90%)
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```
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### 突变测试适用场景
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- 金额计算、权限判断、状态机转换等高风险逻辑
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- 测试覆盖率高但信心不足时
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- 不适用于 UI 组件、配置文件等
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